Tropical Storm Harvey

Tropical Storm Harvey 0400 Hours August 30 2017
Tropical Depression Harvey Satellite 0800 Hours August 31 2017
Tropical Depression Harvey Satellite 0800 Hours August 31 2017

NWS National Hurricane Center Miami FL 400 AM CDT Wed Aug 31 2017

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LOCATION…32.3N 92.0W
ABOUT 15 MILES…20 KM…S OF MONROE LOUISIANA.
ABOUT 65 MILES…105 KM…NNE OF ALEXANDRIA LOUISIANA.
MAXIMUM SUSTAINED WINDS…30 MPH…50 KM/H
PRESENT MOVEMENT…NNE OR 25 DEGREES AT 10 MPH…16 KM/H
MINIMUM CENTRAL PRESSURE…998 MB…29.47 INCHES

AT 400 AM CDT…0900 UTC…THE CENTER OF TROPICAL DEPRESSION HARVEY WAS LOCATED NEAR LATITUDE 32.3 NORTH…AND LONGITUDE 92 WEST. TROPICAL DEPRESSION HARVEY IS MOVING TOWARDS THE NORTHEAST AND IS EXPECTED TO CONTINUE THIS MOTION OVER THE NEXT 48 HOURS. THIS FORECAST TRACK WOULD TAKE HARVEY INTO NORTHWESTERN MISSISSIPPI BY THURSDAY AFTERNOON, THE WESTERN TENNESSEE VALLEY REGION ON FRIDAY, AND INTO THE LOWER OHIO VALLEY EARLY SATURDAY BEFORE ANTICIPATED DISSIPATION BY SATURDAY AFTERNOON.

RAINFALL…TROPICAL DEPRESSION HARVEY IS EXPECTED TO PRODUCE 3 TO 5 INCHES OF RAIN FROM FAR EASTERN ARKANSAS, NORTHERN MISSISSIPPI, NORTHEASTWARD ACROSS WESTERN TO CENTRAL TENNESSEE, WESTERN TO CENTRAL KENTUCKY AND INTO SOUTHERN OHIO. LOCALLY HIGHER TOTALS OF 6 TO 10 INCHES POSSIBLE ACROSS FAR NORTHERN MISSISSIPPI, WESTERN TENNESSEE INTO SOUTHWEST KENTUCKY. THESE RAINS WILL ENHANCE THE FLASH FLOODING RISK ACROSS THESE AREAS, ESPECIALLY FROM FAR NORTHERN MISSISSIPPI, WESTERN TENNESSEE AND INTO FAR SOUTHWEST KENTUCKY.

HOWEVER CATASTROPHIC AND LIFE-THREATENING FLOODING WILL CONTINUE IN AND AROUND HOUSTON, BEAUMONT/PORT ARTHUR, AND EASTWARD INTO SOUTHWEST LOUISIANA FOR THE REST OF THE WEEK. THE EXPECTED HEAVY RAINS SPREADING NORTHEASTWARD FROM LOUISIANA INTO WESTERN KENTUCKY MAY ALSO LEAD TO FLASH FLOODING AND INCREASED RIVER AND SMALL STREAM FLOODING. DO NOT ATTEMPT TO TRAVEL IN THE AFFECTED AREA IF YOU ARE IN A SAFE PLACE. DO NOT DRIVE INTO FLOODED ROADWAYS.

Previous Warning 400 AM CDT Wed Aug 30 201 7

Radar, satellite, and surface observations indicate that Harvey’s center has crossed the coast just west of Cameron, Louisiana, with most of the associated deep convection located over extreme southeastern Texas and western Louisiana. Although the rain has ended in the Houston/Galveston area, the Beaumont/Port Arthur area was particularly hard hit overnight, with about 12.5 inches reported at the Jack Brooks Regional Airport since 7 pm CDT. ASCAT data from late last night indicated that Harvey’s maximum winds were near 40 kt, and the tropical-storm-force wind radii on the eastern side were a little smaller than previously estimated.

Harvey has turned north-northeastward and is moving a little faster with an initial motion of 030/6 kt. The cyclone is located on the northwestern side of a mid-tropospheric high, which should steer it north-northeastward and the northeastward across the Lower Mississippi and Tennessee Valleys during the next few days. The global models indicate that the surface low should dissipate over the Ohio Valley by day 4, which is now indicated in the NHC forecast.

Now that Harvey’s center is moving inland, the maximum winds should gradually decrease during the next few days. Harvey is likely to weaken to a tropical depression by tonight, and then it could become a remnant low by day 3. This weakening will not eliminate the risk of continued heavy rainfall and flooding along Harvey’s path, although the system’s faster motion will prevent rainfall totals from being anywhere near what occurred over southeastern Texas.

Previous Warning 1000 PM CDT Tue Aug 29 2017

 

Latest radar imagery shows that heavy rainfall continues over far eastern Texas and southwestern Louisiana. Outer bands are also producing heavy rain farther east along portions of the northern Gulf coast. However, rains have begun to diminish over the Greater Houston area, where some locations have received more than 50 inches during this historic event.

Harvey took an eastward jog this evening, but recent satellite images suggest that a northeastward motion has resumed. The storm is expected to move north-northeastward to northeastward between a ridge over the eastern Gulf of Mexico and a trough over the east-central United States. This motion should bring the center onshore over southwestern Louisiana early Wednesday, and into the Tennessee Valley region later this week. The global models show the system becoming an open trough near the Ohio Valley or Appalachians in 4 to 5 days. The latest NHC track forecast has been shifted eastward partially due to the more eastward initial position.

There has been little overall change to Harvey’s convective structure since the previous advisory, and the initial intensity remains 45 kt, which was supported by the earlier aircraft data.Little change in strength is anticipate before Harvey reaches the Louisiana coast. After that time, gradual weakening should occur while Harvey moves farther inland.

The latest forecast required an extension of the tropical storm warning eastward to Grand Isle, Louisiana.

Previous Warning 7:00 PM CDT Tue Aug 29 2017

At 700 PM CDT (0000 UTC), the center of Tropical Storm Harvey was estimated near latitude 28.7 North, longitude 93.9 West. Harvey has been moving toward the east near 6 mph (9 km/h) during the past few
hours, however, a north-northeastward motion is expected to resume later tonight and this general motion should continue through tomorrow. On the forecast track, the center of Harvey is expected to move inland over the northwestern Gulf Coast within the tropical storm warning area early Wednesday.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. No significant change in strength is anticipated before the center crosses the coast, but gradual weakening should begin thereafter.

Tropical-storm-force winds extend outward up to 160 miles (260 km) from the center. Within the past few hours a wind gust to 55 mph (89 km/h) has been reported in Galveston. The estimated minimum central pressure is 994 mb (29.36 inches).

Previous Warning 1000 AM CDT Tue Aug 29 2017

 

At 1000 AM CDT (1500 UTC), the center of Tropical Storm Harvey was located near latitude 28.4 North, longitude 94.3 West. Harvey is moving toward the north-northeast near 5 mph (7 km/h). A general north-northeast track is expected today and tomorrow. On the forecast track, the center of Harvey is expected to be just offshore of the middle and upper coasts of Texas through tonight, then move inland over the northwestern Gulf coast early Wednesday.

Maximum sustained winds remain near 45 mph (75 km/h) with higher gusts. No significant change in strength is expected before the center moves inland. A gradual weakening should begin thereafter.

Tropical-storm-force winds extend outward up to 160 miles (260 km)mainly to the east of the center.

The estimated minimum central pressure is 997 mb (29.44 inches).

Previous Warning 400 AM CDT Tue Aug 29 2017

At 400 AM CDT (0900 UTC), the center of Tropical Storm Harvey was located near latitude 28.1 North, longitude 94.8 West. Harvey is moving toward the east near 3 mph (6 km/h), and this motion is expected to continue through this morning. A turn toward the northeast and a continued slow forward speed are expected later today and tonight, followed by a turn toward the north-northeast on Wednesday. On the forecast track, the center of Harvey is expected to be just offshore of the middle and upper coasts of Texas through tonight, then move inland over the northwestern Gulf coast on Wednesday.

Maximum sustained winds are near 45 mph (75 km/h) with higher gusts. Little change in strength is forecast during the next 48 hours.

Tropical-storm-force winds extend outward up to 175 miles (280 km)from the center. An NOS observing site at Texas Point, Sabine Pass, recently reported a sustained wind of 46 mph (74 km/h) with a gust to 56 mph (91 km/h).

The estimated minimum central pressure is 997 mb (29.44 inches).

Previous Warning 400 PM CDT Mon Aug 28 2017

Radar and surface data show that the center of Harvey remains near or just off the Texas coast south of Matagorda. The associated convection has increased in intensity and coverage in a cluster extending from just north of the center northeastward into the Houston metropolitan area. Surface observations indicate that the central pressure is around 997 mb, and there are recent reports of sustained tropical-storm-force winds about 50-60 n mi southwest of the center. Based on these, the initial intensity is increased to 40 kt.

Very heavy rains and life-threatening flash flooding continue over southeastern Texas and southwestern Louisiana. There have been reports of 2-day rainfall totals of close to 35 inches in the Greater Houston area. With the additional rains that are expected over the next several days, rainfall totals could reach 50 inches in some locations, which would be historic for the area.

While Harvey continues to produce widespread heavy rain, the convective structure is not well organized in terms of being a tropical cyclone. In addition, a dry slot is seen in water vapor imagery over the southern and southeastern parts of the circulation, and the intensity guidance is not showing much additional development as Harvey crosses the northwestern Gulf of Mexico. The intensity forecast reflects these issues by showing little change in strength before landfall. Weakening and eventual decay into a remnant low are expected after landfall.

The center has drifted erratically eastward since the last advisory, although a longer-term motion is 110/3. Harvey is currently between the subtropical ridge over the Gulf of Mexico and a large deep-layer ridge over the western United States, with a large trough in the westerlies weakening the Gulf ridge just enough to allow an east-southeastward motion. The large-scale models suggest that the westerlies should erode the western ridge to some
extent during the forecast period, which should allow Harvey to turn north-northeastward under the greater influence of the Gulf ridge. The track guidance has changed little since the previous advisory except to show a faster motion from 96-120 h. The new forecast track remains close to that of the previous track, except for an increased forward speed by 120 h.

INIT 28/2100Z 28.5N 95.7W 45 MPH (NE of Matagorda, Texas)
12H 29/0600Z 28.4N 95.5W 45 MPH (SE of Matagorda, Texas)
24H 29/1800Z 28.6N 95.0W 45 MPH (S of Freeport, Texas)
36H 30/0600Z 29.2N 94.5W 45 MPH (S of Galveston, Texas)
48H 30/1800Z 30.3N 94.1W 40 MPH (SW of Evadale, Texas)
72H 31/1800Z 32.5N 93.0W 35 MPH (E of Mount Lebanon, Texas)
96H 01/1800Z 34.5N 91.5W 30 MPH (SE of Little Rock, AR)
120H 02/1800Z 37.0N 89.0W 25 MPH (SW of Paducah, KY

Hurricane Harvey Live Webcams

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Previous Warning 700 AM CDT Mon Aug 28 2017

At 700 AM CDT (1200 UTC), the center of Tropical Storm Harvey was located near latitude 28.6 North, longitude 96.1 West. Harvey is moving toward the southeast near 3 mph (6 km/h) and a slow southeastward motion is expected today. A slow northeastward motion is expected to begin on Tuesday. The center of Harvey is emerging off of the middle Texas coast, and it is expected to remain just offshore through Tuesday.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Slight restrengthening is possible later today and Tuesday. Tropical-storm-force winds extend outward up to 175 miles (280 km) from the center.

The minimum central pressure estimated from surface observations along the Texas coast is 997 mb (29.44 inches).

HAZARDS AFFECTING LAND
———————-
RAINFALL: Harvey is expected to produce additional rainfall accumulations of 15 to 25 inches through Friday over the upper Texas coast and into southwestern Louisiana. Isolated storm totals may reach 50 inches over the upper Texas coast, including the Houston/ Galveston metropolitan area. These rains are currently producing catastrophic and life-threatening flooding, and flash flood emergencies are in effect for portions of southeastern Texas. DO NOT ATTEMPT TO TRAVEL IN THE AFFECTED AREA IF YOU ARE IN A SAFE PLACE. DO NOT DRIVE INTO FLOODED ROADWAYS.

Previous Warning 700 PM CDT Sun Aug 27 2017

At 700 PM CDT (0000 UTC), the center of Tropical Storm Harvey was located inland near latitude 28.9 North, longitude 96.8 West. Harvey is moving toward the southeast near 3 mph (4 km/h), and a slow southeastward motion is expected over the next couple of days. On the forecast track, the center of Harvey is forecast to move off the middle Texas coast on Monday and meander just offshore through
Monday night.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Little change in strength is forecast during the next 24 hours. Some slight restrengthening is possible after the center moves off the coast on Monday night and Tuesday. Tropical-storm-force winds extend outward up to 140 miles (220 km)primarily over water to the east of the center.

The estimated minimum central pressure is 1000 mb (29.53 inches).

Previous Warning 1000 AM CDT Sun Aug 27 2017

FLASH FLOOD EMERGENCIES IN PARTS OF SOUTHEASTERN TEXAS INCLUDING GREATER HOUSTON. DO NOT ATTEMPT TO TRAVEL IN THE AFFECTED AREA IF YOU ARE IN A SAFE PLACE AND DO NOT DRIVE INTO FLOODED ROADWAYS.

SUMMARY OF 1000 AM CDT…1500 UTC…INFORMATION

LOCATION…29.0N 97.4W
ABOUT 35 MI…55 KM WNW OF VICTORIA TEXAS
ABOUT 70 MI…115 KM ESE OF SAN ANTONIO TEXAS
MAXIMUM SUSTAINED WINDS…40 MPH…65 KM/H
PRESENT MOVEMENT…SSE OR 160 DEGREES AT 2 MPH…4 KM/H
MINIMUM CENTRAL PRESSURE…1000 MB…29.53 INCHES

At 1000 AM CDT (1500 UTC), the center of Tropical Storm Harvey was located near latitude 29.0 North, longitude 97.4 West. Harvey is moving toward the south-southeast near 2 mph (4 km/h), and a slow southeastward to east-southeastward motion is expected over the next couple of days. On the forecast track, the center will move very near the coast of southeastern Texas.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts.Little change in strength is forecast during the next 48 hours.

Tropical-storm-force winds extend outward up to 175 miles (280 km)primarily over water to the east and northeast of the center.

The estimated minimum central pressure is 1000 mb (29.53 inches).

RAINFALL: Harvey is expected to produce additional rainfall accumulations of 15 to 25 inches through Friday over the middle and upper Texas coast, including the Houston/Galveston metropolitan area. Isolated storm totals may reach 50 inches in this region. These rains are currently producing catastrophic and life- threatening flooding, and flash flood emergencies are in effect for portions of southeastern Texas.

Previous Warning 400 AM CDT Sun Aug 27 2017

Although the radar presentation of the inner core of Harvey has degraded considerably, the system continues to produce intense convection in bands to the east and southeast of the center. The current intensity estimate is set to 40 kt based on surface  synoptic data over southeastern Texas. Since the center is expected to remain mainly over land during the forecast period, continued weakening is likely. Given that a significant portion of the circulation is over water, however, this weakening should be
very slow to occur. The official intensity forecast is similar to the model consensus.

Harvey has been meandering overnight and now appears to be drifting south-southwestward. The cyclone is trapped between mid-level highs to its west-northwest and east-southeast. Over the next couple of days, the flow on the southern periphery of a trough dropping over the east-central United States should cause Harvey to move slowly southeastward to eastward. Later in the forecast period, increased ridging to east of the cyclone should cause Harvey to turn northward. The official track forecast is close to the latest model consensus and brings the center to the coast and, briefly, just offshore of southeastern Texas. At this time, it is not expected that Harvey will move far enough out over the water to result in regeneration.

The biggest concern with Harvey is now the rain, a lot of rain.Rainfall totals of nearly 20 inches have been reported in the Houston area. This is resulting in catastrophic flooding which,unfortunately, will continue for some time.

Key Messages:

1. While Harvey’s winds are decreasing, life-threatening hazardswill continue from heavy rainfall over much of southeasternTexas and from storm surge along portions of the Texas coast.

2. Catastrophic and life-threatening flooding is expected across the middle and upper Texas coast from additional rainfall of 15 to25 inches, with isolated storm totals as high as 40 inches, through Thursday. Please heed the advice of local officials and do not drive into flooded roadways. Refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard.

3. A Storm Surge Warning remains in effect for portions of the Texas coast. Life-threatening storm surge flooding will be slow to
recede due to the slow motion of Harvey and a prolonged period of onshore flow.

INIT 27/0900Z 29.2N 97.7W 45 MPH (NE of Gillett, Texas )
12H 27/1800Z 29.0N 97.4W 40 MPH (NE of Yorktown, Texas)
24H 28/0600Z 28.7N 97.0W 35 MPM (S of Victoria, Texas)
36H 28/1800Z 28.5N 96.6W 35 MPH (W of Indianola,  Texas)
48H 29/0600Z 28.5N 96.1W 35 MPH (SE of Port O’Connor, Texas)
72H 30/0600Z 29.4N 95.6W 35 MPH (NW of Sandy Point, Texas)
96H 31/0600Z 30.8N 95.5W 30 MPH (NW of Arizona, Texas)
120H 01/0600Z 32.0N 95.0W 30 MPH (E of Jacksonville, Texas)

Previous Warning 400 PM CDT Sat Aug 26 2017

 

Harvey has continued to weaken while located inland over Texas. Doppler radar data indicate that winds are now 55 kt, and since there are no surface observations near the center, this is the intensity used in this advisory. A continued weakening is anticipated, and the NHC forecast uses the trend provided by the
SHIPS decay model. However, if a large portion of Harvey’s circulation remains over the Gulf of Mexico, the cyclone could weaken at a slower rate than shown here.

Harvey has barely moved during the past few hours and little motion is anticipated. Since the steering currents are forecast to remain light, Harvey could easily meander for the next 4 to 5 days over southeast Texas as indicated in the NHC forecast. Guidance disagrees in which direction the cyclone will move, but all the models agree that any motion will be quite slow.

Key Messages:

While Harvey’s winds are decreasing, life-threatening hazards will continue from heavy rainfall over much of southeastern Texas and from storm surge along portions of the Texas coast.

Catastrophic and life-threatening flooding is expected across the middle and upper Texas coast from additional rainfall of 15 to 25 inches, with isolated storm totals as high as 40 inches, through Thursday. Please heed the advice of local officials and do not drive into flooded roadways. Refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard. A summary of rainfall totals compiled by the Weather Prediction Center can be found at: www.wpc.ncep.noaa.gov/discussions/nfdscc1.html

A Storm Surge Warning remains in effect for portions of the Texas coast. Life-threatening storm surge flooding will be slow to recede due to the slow motion of Harvey and a prolonged period of onshore flow. For a depiction of areas at risk, see the Storm Surge Watch/Warning Graphic at hurricanes.gov.

INIT 26/2100Z 29.1N 97.6W 65 MPH (SW of Yokum, Texas)
24H 27/1800Z 28.9N 97.7W 40 MPH (NE of Runge, Texas)
36H 28/0600Z 28.5N 97.3W 35 MPH (E of Sarco, Texas)
48H 28/1800Z 28.3N 97.1W 35 MPH (E of Refugio, Texas)
72H 29/1800Z 28.7N 97.0W 35 MPH (S of Victoria, Texas)
96H 30/1800Z 29.5N 97.0W 35 MPH (E of Gonzales, Texas)
120H 31/1800Z 30.5N 97.0W 35 MPH (W of Tanglewood, Texas)

Previous Warning 1000 AM CDT Sat Aug 26 2017

Harvey has been inland for about 12 hours and weakening is under way. Doppler radar data indicate that winds have decreased to 65 kt, and that is the intensity used in this advisory. Since Harvey is over land, a continued weakening is anticipated, and the NHC forecast uses the trend provided by the SHIPS decay model. However, if a portion of Harvey’s circulation remains over the Gulf of Mexico, the cyclone could weaken at a slower rate than shown here.

The hurricane is moving very slowly toward the north at about 2 kt. Harvey is embedded within very light steering currents, and global models keep this weak flow in place for the next several days. Based
on this pattern, Harvey could easily meander for the next 4 to 5 days over southeast Texas as indicated in the NHC forecast. The only agreement among the track guidance is that Harvey is certainly not going anywhere fast.

This slow motion of the cyclone is expected to exacerbate the potential for catastrophic flooding from heavy rainfall at least through the middle of next week.

INIT 26/1500Z 28.9N 97.3W 75 MPH (S of Meyersville, Texas)
12H 27/0000Z 29.1N 97.4W 50 MPH (W of Cuero, Texas)
24H 27/1200Z 29.2N 97.5W 45 MPH (W of Westhoff, Texas)
36H 28/0000Z 29.0N 97.5W 40 MPH (N of Yorktown, Texas)
48H 28/1200Z 28.7N 97.0W 35 MPH (S of Victoria, Texas)
72H 29/1200Z 28.7N 96.7W 35 MPH (NW of Port Lavaca, Texas)
96H 30/1200Z 29.5N 96.7W 35 MPH (NW of Sheridan, Texas)
120H 31/1200Z 30.5N 96.5W 35 MPH (SW of College Station)

Previous Warning 500 AM CDT Sat Aug 26 2017

SUMMARY OF 500 AM CDT…1000 UTC…INFORMATION
———————————————-
LOCATION…28.5N 97.2W
ABOUT 30 MI…50 KM SW OF VICTORIA TEXAS
ABOUT 105 MI…170 KM SE OF SAN ANTONIO TEXAS
MAXIMUM SUSTAINED WINDS…90 MPH…150 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 6 MPH…9 KM/H
MINIMUM CENTRAL PRESSURE…967 MB…28.56 INCHES

Previous Warning 400 AM CDT Sat Aug 26 2017

HARVEY MOVING SLOWLY INLAND OVER SOUTH TEXAS. CATASTROPHIC FLOODING EXPECTED OVER THE NEXT FEW DAYS DUE TO HEAVY RAINFALL.

SUMMARY OF 400 AM CDT…0900 UTC…INFORMATION
———————————————-
LOCATION…28.5N 97.2W
ABOUT 30 MI…50 KM SW OF VICTORIA TEXAS
ABOUT 105 MI…170 KM SE OF SAN ANTONIO TEXAS
MAXIMUM SUSTAINED WINDS…100 MPH…155 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 6 MPH…9 KM/H
MINIMUM CENTRAL PRESSURE…963 MB…28.44 INCHES

At 400 AM CDT (0900 UTC), the eye of Hurricane Harvey was located by NOAA Doppler radar near latitude 28.5 North, longitude 97.2 West. Harvey is moving toward the northwest near 6 mph (9 km/h). Harvey is expected to slow down through the day and meander over southeastern Texas through the middle of next week.

Doppler radar data indicate that maximum sustained winds have decreased to near 100 mph (155 km/h) with higher gusts. Additional weakening is forecast, and Harvey is likely to become a tropical storm later today.

Hurricane-force winds extend outward up to 35 miles (55 km) from the center, and tropical-storm-force winds extend outward up to 140 miles (220 km).

The estimated minimum central pressure is 963 mb (28.44 inches).

Almost 10 inches of rain have already been reported at a few locations in southeastern Texas.

Previous Warning 900 PM CDT Fri Aug 25 20179 EYE OF CATEGORY 4 HARVEY ALMOST ONSHORE.

A station at Aransas Pass run by the Texas Coastal Observing Network recently reported a sustained wind of 102 mph (165 km/h) with a gust to 120 mph (193 km/h).

A station at Aransas Wildlife Refuge run by the Texas Coastal Observing Network recently reported a sustained wind of 71 mph (115 km/h) with a gust to 102 mph (165 km/h).

SUMMARY OF 900 PM CDT…0200 UTC…INFORMATION
———————————————-
LOCATION…27.9N 96.9W
ABOUT 30 MI…50 KM ENE OF CORPUS CHRISTI TEXAS
ABOUT 45 MI…75 KM SW OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS…130 MPH…215 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 8 MPH…13 KM/H
MINIMUM CENTRAL PRESSURE…941 MB…27.79 INCHES

Previous Warning 700 PM CDT Fri Aug 25 2017

At 700 PM CDT (0000 UTC), the eye of Hurricane Harvey was located by reconnaissance aircraft and NOAA Doppler radar near latitude 27.8 North, longitude 96.8 West. Harvey is moving toward the northwest near 8 mph (13 km/h), but its forward speed is expected to decrease during the next couple of days. On the forecast track, Harvey will make landfall on the middle Texas coast during the next several
hours. Harvey is then likely to meander near or just inland of the middle Texas coast through the weekend.

Reports from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds remain near 130 mph (215 km/h) with higher gusts. Harvey is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Little change in strength is likely before landfall. Weakening is then expected over the weekend while the center moves inland over Texas.

Hurricane-force winds extend outward up to 35 miles (55 km) from the center, and tropical-storm-force winds extend outward up to 140 miles (220 km). A Texas Coastal Ocean Observing Network station at Aransas Pass recently reported sustained winds of 79 mph (128 km/h) and a wind gust of 101 mph (163 km/h). The latest minimum central pressure reported by the Hurricane Hunter aircraft is 941 mb (27.79 inches)

Previous Warning  600 PM CDT Fri Aug 25 2017

Cruise Ship Weather: Hurricane Harvey Category 4

Despite its concentric eyewall structure, Harvey’s winds have increased during the day. NOAA and Air Force Reserve Hurricane Hunter planes have measured maximum flight-level winds of 129 kt and SFMR winds to 102 kt. Based on these data, Harvey’s maximum  surface winds are estimated to be 110 kt. Harvey’s central pressure has also continued to fall, and the latest estimate based on dropsonde data is 941 mb.

Harvey still has not slowed down, and the initial estimate is 325/9 kt. Based on the forecast track, Harvey is expected to make landfall along the middle Texas coast tonight. After that, the track models insist that the hurricane will slow down considerably during the next 24 hours, and it is likely to move very little between 36 and 120 hours. In fact, there has been a somewhat notable change in the guidance, with very few of the models showing Harvey lifting out toward the northeast by the end of the 5-day forecast period. As a result, the NHC track forecast has been pulled back a bit and keeps Harvey near or just inland of the Texas coast through the middle of next week. This slow motion only  exacerbates the heavy rainfall and flooding threat across southern and southeastern Texas.

Harvey may continue to strengthen during the 6-12 hours it has before landfall, but regardless it is expected to make landfall at major hurricane strength. Gradual weakening is anticipated after the center moves inland, but Harvey’s slow motion will keep a significant portion of its circulation over water, which may slow the weakening rate. As a result, the NHC intensity forecast leans closer to the global model guidance instead of the statistical- dynamical guidance, which seems to weaken Harvey too fast. Harvey could maintain tropical storm strength for the entire 5-day
forecast period due to its proximity to the northwestern Gulf of Mexico.

12H 26/0600Z 28.2N 97.0W 115 MPH (N of Holiday Beach, Texas)
24H 26/1800Z 28.8N 97.5W 85 MPH (N of Angel City, Texas)
36H 27/0600Z 28.9N 97.8W 70 MPH (S of Helena, Texas)
48H 27/1800Z 28.6N 97.8W 60 MPH (S of Pettus, Texas)
72H 28/1800Z 28.1N 96.9W 45 MPH (San Jose Island, Texas)
96H 29/1800Z 28.5N 96.0W 45 MPH (S of Matagorda)
120H 30/1800Z 29.5N 95.5W 40 MPH (W of Arcola,  Texas)

Previous Warning 1000 AM CDT Thu Aug 25 2017

Multiple observing platforms indicate that Harvey’s structure is evolving this morning. The hurricane has developed concentric eyewalls, as observed in data from the WSR-88D Doppler radars in Brownsville and Corpus Christi, and an Air Force Reserve Hurricane Hunter plane reported double wind maxima with diameters of 12 and 28 n mi. The aircraft data indicate that the central pressure has continued to fall–now down to 947 mb–but the maximum winds have not increased further. This discrepancy is not surprising given hurricane’s current structure.

Intensity forecasts become complicated once a hurricane develops concentric eyewalls, and fluctuations in intensity become more likely. If an eyewall replacement occurs, then Harvey’s intensity could decrease a bit while at the same time the overall wind field increases in size. However, the hurricane remains in an environment for intensification, and strengthening beyond the current intensity  is still possible before the center reaches land. But in the end, the hurricane’s exact intensity at landfall does not change the fact that catastrophic flooding due to a prolonged period of heavy rainfall and/or storm surge is expected at the coast and well inland across much of southern and southeastern Texas. Slow weakening is expected after Harvey crosses the coast since the center is not expected to move very far inland, and the cyclone is likely to maintain tropical storm status through Wednesday.

Harvey has not quite begun to slow down, and the initial motion estimate is 315/9 kt. Strong mid-level ridging building over the western United States is still expected to impede Harvey’s forward motion in the coming days, and the track guidance continues to show the hurricane meandering or stalling near or just inland of the Texas coast in 36-48 hours. Harvey could begin moving slowly eastward on days 4 and 5 due to the influence of a mid-level shortwave trough digging southward over the upper Midwest, but at this time it is too early to say whether the center will definitely re-emerge over the northwestern Gulf of Mexico.

12H 26/0000Z 27.6N 96.8W 120 MPH (SE of Corpus Christi, Texas)
24H 26/1200Z 28.4N 97.3W 105 MPH (NE of Rockport, Texas))
36H 27/0000Z 28.8N 97.5W 80 MPH (NE of Angel City, Texas))
48H 27/1200Z 28.9N 97.6W 65 MPH (SE of Nordheim, Texas)
72H 28/1200Z 28.3N 96.8W  40 MPH (N of Matagorda Island, Texas)
96H 29/1200Z 28.5N 95.5W 45 MPH  (E of Matagorda, Texas)
120H 30/1200Z 30.0N 94.5W 45 MPH (NE of Texas City)

Previous Warning 700 AM CDT Thu Aug 25 2017

At 700 AM CDT (1200 UTC), the eye of Hurricane Harvey was located by Air Force Reserve reconnaissance aircraft and NOAA Doppler radar near latitude 26.3 North, longitude 95.8 West. Harvey is moving toward the northwest near 10 mph (17 km/h), but its forward speed is expected to decrease significantly during the next couple of days. On the forecast track, Harvey will make landfall on the
middle Texas coast tonight or early Saturday. Harvey is then likely to meander near or just inland of the middle Texas coast through the weekend.

Maximum sustained winds are near 110 mph (175 km/h) with higher gusts. Some strengthening is possible, and Harvey is expected to become a major hurricane before it reaches the middle Texas coast.

Hurricane-force winds extend outward up to 35 miles (55 km) from the center, and tropical-storm-force winds extend outward up to 140 miles (220 km). The minimum central pressure reported by the Air Force plane was 950 mb (28.05 inches).

Previous Warning 4 00 AM CDT Fri Aug 25 2017

LOCATION…25.2N 94.6W
ABOUT 250 MI…400 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 245 MI…400 KM SSE OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS…85 MPH…140 KM/H
PRESENT MOVEMENT…NW OR 315 DEGREES AT 10 MPH…17 KM/H
MINIMUM CENTRAL PRESSURE…973 MB…28.74 INCHES

Projected Track
12H 25/1200Z 26.1N 95.6W 110 MPH Category 2 (E of Brownsville, Texas)
24H 26/0000Z 27.2N 96.5W 125 MPH Category 3 (SE of Corpus Christi, Texas)
36H 26/1200Z 28.1N 97.1W 115 MPH Category 2 (Copano Bay, Texas)
48H 27/0000Z 28.6N 97.3W 80 MPH (SE of Goliad, Texas)
72H 28/0000Z 28.5N 97.5W 40 MPH ( SW of Sarco, Texas)
96H 29/0000Z 28.5N 97.0W 40 MPH (S of McFaddin, Texas)
120H 30/0000Z 29.5N 95.0W 35 40 MPH (E of League City, Texas)

Previous Warning 700 PM CDT Thu Aug 24 2017

LOCATION…25.0N 94.3W
ABOUT 275 MI…445 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 270 MI…435 KM SSE OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS…85 MPH…140 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 10 MPH…17 KM/H
MINIMUM CENTRAL PRESSURE…974 MB…28.76 INCHES

At 700 PM CDT (0000 UTC), the eye of Hurricane Harvey was located near latitude 25.0 North, longitude 94.3 West. Harvey is moving toward the northwest near 10 mph (17 km/h). This general motion is expected to continue with a decrease in forward speed during the next couple of days. On the forecast track, Harvey will approachthe middle Texas coast on Friday and make landfall Friday night or early Saturday. Harvey is then likely to stall near or just inland of the middle Texas coast through the weekend.

Reports from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds remain near 85 mph (140 km/h) with higher gusts. While Harvey has changed little in strength over the past few hours, strengthening is expected to resume during the next few hours, and Harvey is expected to become a major hurricane by Friday before it reaches the middle Texas coast.

Hurricane-force winds extend outward up to 25 miles (35 km) from  the center, and tropical-storm-force winds extend outward up to 90
miles (150 km).

The minimum central pressure just reported by the Hurricane Hunter Aircraft is 974 mb (28.76 inches).

Previous Warning 400 PM CDT Thu Aug 24 2017

Since the issuance of the special advisory at 1800 UTC, data from a dropsonde released by a NOAA Hurricane Hunter aircraft indicated that Harvey’s central pressure has dropped to 976 mb. However, the
plane has not measured winds stronger than what was observed by the previous Air Force flight (although the NOAA P3 is flying a research mission at a nonstandard level). For now, the initial intensity will remain 75 kt pending data from another Air Force flight this evening.

Harvey’s initial motion estimate is 330/9 kt. A strengthening mid-level high over the eastern Gulf of Mexico is expected to push Harvey northwestward by tonight, and a northwest or north-northwest
motion should continue up until landfall. However, a stronger mid-level high centered over the western United States is forecast to cause Harvey to slow down considerably and stall near or justinland of the Texas coast by days 3 and 4. After that time, the track models have trended toward showing Harvey moving slowly eastward by day 5, but it’s too early to know if the center will remain over land or re-emerge over the northwestern Gulf of Mexico. The track guidance is very tightly clustered for the first 36-48 hours, which covers the period of landfall, but then there is much greater spread in the models after 48 hours when Harvey is forecast to slow down. Such guidance is usually an indication that the cyclone will move very little, which is reflected in the official forecast.

Harvey remains in an environment for further strengthening. Vertical shear is low, and the hurricane will be moving over a warm eddy of relatively higher oceanic heat content within the next 12-24 hours. As a result, the NHC intensity forecast calls for additional intensification at least for the next 24 hours, with Harvey expected to attain major hurricane strength on Friday.

There may be some fluctuations in intensity up until landfall due to the possibility of an eyewall replacement or cooling of the shallow shelf waters of Texas, but regardless Harvey is forecast to reach the coast as a major hurricane. The intensity forecast after 48 hours is tricky because it all depends on how far inland Harvey moves into Texas. If it stays stalls closer to the coast, as recent model trends have suggested, then the cyclone may be able to maintain a higher intensity with a greater proportion of its circulation remaining over water. For that reason, the updated NHC intensity forecast keeps Harvey as a tropical storm on days 3 through 5, but there is greater-than-normal uncertainty in this part of the forecast.

12H 25/0600Z 25.5N 94.8W 110 MPH Category 2 (SE of Brownsville, Texas)
24H 25/1800Z 26.7N 96.0W 125 MPH Category 3 (SE of Corpus Christi,  Texas)
36H 26/0600Z 27.8N 96.7W 120 MPH Category 3 (E of Port Aransas,  Texas)
48H 26/1800Z 28.5N 97.1W 100 MPH Category 2 (SW of McFaddin, Texas)
72H 27/1800Z 28.7N 97.2W 50 MPH (E of Fannin,  Texas)
96H 28/1800Z 28.5N 96.5W 40 MPH (N of Port O’Connor, Texas)
120H 29/1800Z 29.0N 95.0W  40 MPH (S of Galveston Island, Texas)

Previous Warning 1200PM

Data from an Air Force Reserve Hurricane Hunter aircraft indicate that Harvey has intensified to a hurricane, with maximum sustained winds of 80 mph (130 km/h).

A Special Advisory will be issued by 1 PM CDT (1800 UTC) in lieu of the intermediate advisory to update the intensity forecast.

SUMMARY OF 1200 PM CDT…1700 UTC…INFORMATION
———————————————-
LOCATION…24.3N 93.5W
ABOUT 340 MI…550 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 335 MI…540 KM SSE OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS…80 MPH…130 KM/H
PRESENT MOVEMENT…NNW OR 335 DEGREES AT 10 MPH…17 KM/H
MINIMUM CENTRAL PRESSURE…981 MB…28.97 INCHES

Previous Warning 1000 AM CDT Thu Aug 24 2017

Data from an Air Force Hurricane Hunter aircraft indicate that Harvey is quickly strengthening, and the cyclone’s structure has improved markedly with the plane reporting a closed 15-20 n mi wide eye. The flight-level and SFMR winds support an intensity of 55 kt, but one of the more notable measurements is the central pressure, which has fallen to 982 mb. With a pressure this low, it is likely that the winds will respond and increase further, and Harvey probably isn’t too far from becoming a hurricane.

With Harvey now strengthening at a faster rate than indicated in previous advisories, the intensity forecast has become quite concerning. Water vapor images indicate that the cyclone’s outflow is expanding–indicative of low shear–and Harvey will be moving over a warm eddy of high oceanic heat content in the western Gulf of Mexico in about 24 hours. As a result of these conditions, several intensity models, including the ICON intensity consensus, are now explicit showing Harvey reaching major hurricane intensity. What’s more astounding is that some of the SHIPS Rapid Intensification indices are incredibly high. As an example, the guidance is indicating a 70 percent chance of Harvey’s winds increasing by 45 kt
over the next 36 hours. Based on this guidance, the NHC official intensity forecast now calls for Harvey to reach major hurricane strength by 36 hours, before it reaches the middle Texas coast.

Aircraft fixes indicate that Harvey has turned toward the north- northwest, and the initial motion estimate is 340/9 kt. A mid- level high centered near Florida and the eastern Gulf of Mexico should force Harvey toward the northwest later today, with that trajectory continuing for the next couple of days. By 48 hours, the cyclone appears to get sandwiched between the same mid-level high over the Gulf of Mexico and a larger high over the
Intermountain West, which will cause Harvey to slow down considerably during its approach toward the Texas coast and then potentially stall just inland on days 3 through 5. Mainly based on an adjustment of the initial position, the NHC forecast track has been nudged northeastward on this cycle, but it still lies relatively close to the TVCN multi-model consensus and the HFIP Corrected Consensus Approach (HCCA).

It is critical that users not focus on the exact forecast track of Harvey, since cycle-to-cycle adjustment are likely. All locations within the hurricane and storm surge warning areas should be preparing for the possibility of major hurricane-force winds and life-threatening storm surge.

Key Messages:

1. Harvey has intensified quickly this morning, and is now forecast to be a major hurricane at landfall, bringing life-threatening storm surge, rainfall, and wind hazards to portions of the Texas coast. Preparations to protect life and property should be completed by tonight, as tropical-storm-force winds will first arrive in the hurricane and storm surge warning areas on Friday.

2. A Storm Surge Warning is in effect for much of the Texas coast. Life-threatening storm surge flooding could reach heights of 6 to 10 feet above ground level at the coast between the north entrance of the Padre Island National Seashore and Sargent. For a depiction of areas at risk, see the Storm Surge Watch/Warning Graphic at hurricanes.gov.

3. Life-threatening flooding is expected across much of the Texas coast from heavy rainfall of 12 to 20 inches, with isolated amounts as high as 30 inches, from Friday through early next week. Please refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard.

4. The Potential Storm Surge Flooding Map is available on the NHC website. This product depicts a reasonable worst-case scenario – the amount of inundation that has a 10 percent chance of being exceeded at each individual location. This map best represents the flooding potential in those locations within the watch and warning areas.

FORECAST POSITIONS AND MAX WINDS

INIT 24/1500Z 24.0N 93.3W 65 MPH (E of Tamaulipas, Mexico)
12H 25/0000Z 24.9N 94.2W 80 MPH Category 1 (SE of Brownsville, Texas)
24H 25/1200Z 26.0N 95.3W 105 MPH Category 2 (E of Brownsville, Texas)
36H 26/0000Z 27.3N 96.3W 115 MPH Category 3 (SE of Corpus Christi, Texas)
48H 26/1200Z 28.3N 97.0W 110 MPH (N of Port Aransas, Texas)
72H 27/1200Z 29.0N 97.7W 45 MPH (N of Runge, Texas)
96H 28/1200Z 28.5N 97.5W 40 MPH (W of Sarco, Texas)
120H 29/1200Z 28.5N 96.5W 35 MPH (Powderhorn Lake, Texas)

Previous Warning 700 AM CDT

Tropical Storm Harvey was located by a reconnaissance plane near latitude 23.8 North, longitude 93.0 West. Harvey is moving toward the north-northwest near 10 mph (17 km/h). A track toward the northwest or north-northwest at a faster forward speed is expected for the next 48 hours. On the forecast track, Harvey will approach the southern Texas coast on Friday.

An Air Force Reserve aircraft reports that the maximum sustained winds have increased to near 60 mph (95 km/h) with higher gusts. Additional strengthening is forecast during the next 48 hours, and Harvey is expected to become a hurricane by Friday.

Tropical-storm-force winds extend outward up to 115 miles (185 km)
from the center.

The minimum central pressure based on data from the Air Force Hurricane Hunter aircraft is 986 mb (29.12 inches).

HAZARDS AFFECTING LAND
———————-
RAINFALL: Harvey is expected to produce total rain accumulations of  10 to 15 inches with isolated maximum amounts of 25 inches over the Texas coast through next Wednesday. During the same time period Harvey is expected to produce total rain accumulations of 3 to 9 inches along its outer radius including parts of south, central, and eastern Texas and the lower Mississippi Valley. Rainfall from Harvey may cause life-threatening flooding.

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water is expected to reach the following heights above ground if the peak surge occurs at the time of high tide…

Port Mansfield to San Luis Pass…5 to 7 ft
San Luis Pass to High Island…2 to 4 ft
Mouth of the Rio Grande to Port Mansfield…2 to 4 ft

The deepest water will occur along the immediate coast near and to the northeast of the landfall location, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

WIND: Hurricane conditions are likely within the hurricane warning area late Friday or Friday night, with tropical storm conditions expected to first reach the coast in the hurricane warning area Friday.

Previous Warning  400 AM CDT Thu Aug 24 2017

NOAA and Air Force Hurricane Hunter planes have been sampling Harvey during the past few hours. Both aircraft indicate that Harvey is becoming better organized and the central pressure is falling. An average of the flight-level winds and the SFMR yield an initial intensity of 40 kt. There are some unconfirmed reports of stronger winds at flight-level to the northeast of the center, but I am waiting for the plane to go back to that area for confirmation.

It appears that the environment has finally become favorable and all of the guidance calls for intensification. In fact, the Rapid Intensification Index is up to 45 percent. The current NHC forecast is a little lower than the model consensus to maintain continuity from the previous advisory. If the current intensity trend continues, the winds will have to be adjusted upward in the next advisory.

The initial motion is toward the north or 360 degrees at 9 kt. However, this is a combination of motion and reformation under the convection. Harvey is already on the western edge of the subtropical ridge extending from the Atlantic westward across the Gulf of Mexico. This pattern will steer the cyclone on a general northwest to north-northwest track for the next 2 to 3 days. Once Harvey makes landfall in Texas, most of the global models predict that the steering currents will collapse and Harvey will begin to meander over Texas and perhaps will move back into the northwestern Gulf of Mexico.

Previous Warning 1000 PM CDT Wed Aug 23 2017

Reports from an Air Force Reserve Hurricane Hunter aircraft suggest that Harvey’s structure has consolidated a little bit, with the pressure falling to 1002 mb and the radius of maximum winds shrinking to 60 n mi. However, there have been no reliable reports of winds indicating that the cyclone has reached tropical-storm strength, and the convective cloud pattern remains ragged. Based on these data, the initial intensity is held at 30 kt. Perhaps the most significant finding of the aircraft is that the center was to the east of the previous advisory position.

The initial motion is a rather uncertain 325/2. A weak mid-level ridge to the northeast of Harvey should cause the cyclone to move on a northwestward or north-northwestward track through 48-72 h, and this motion should bring the center inland over southern Texas. Later, steering currents weaken as a ridge builds over the southwestern United States and a trough drops down from the Plains. As a result, Harvey should decelerate while making landfall and move very slowly just inland of the coast.

There is a major spread amongst the large-scale models from 72-120 h, with the UKMET forecasting a slow northward motion into eastern Texas, the GFS a southwestward motion over Texas, and a cyclonic loop that moves the system back over the Gulf of Mexico. Given the uncertainty, the new forecast track shows a slow motion over southern Texas during that time, with a change from the small right turn of the previous forecast to a small left turn. Overall, the track lies a little to the right of the consensus models through 72h.

An upper-level low seen in water vapor imagery over the northwestern Gulf of Mexico appears to be weakening, and as this happens Harvey should end up in a low shear environment. This should allow strengthening over deep warm water in the western Gulf of Mexico. The new intensity forecast is adjusted slightly to show Harvey explicitly becoming a hurricane in 48 h, and some additional strengthening could occur between the 48 h point and landfall. After landfall, Harvey is expected to weaken. However, the forecast track keeps the system close enough to the Texas coast that this weakening is likely to be slower than normal.

Since Harvey has moved slower than anticipated during the past 6-12 h, warnings are not yet required for portions of the Texas coast. Warnings are likely to be issued sometime on Thursday.

Key Messages:

1. Harvey is likely to bring multiple hazards, including heavy rainfall, storm surge, and possible hurricane conditions to portions of the Texas coast beginning on Friday.

2. Heavy rainfall is likely to spread across portions of eastern Texas, Louisiana, and the lower Mississippi Valley from Friday through early next week and could cause life-threatening flooding. Please refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard.

3. A Storm Surge Watch is in effect from Port Mansfield to High Island, Texas, indicating the possibility of life-threatening inundation from rising water moving inland from the coast during the next 48 hours. For a depiction of areas at risk, see the Storm Surge Watch/Warning Graphic at hurricanes.gov.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0300Z 21.9N 92.6W 35 MPH (NW of Merida, Mexico)
12H 24/1200Z 22.8N 93.1W 40 MPH (N of Tabasco, Mexico)
24H 25/0000Z 24.1N 94.1W 45 MPH (E  of Tamaulipas, Mexico)
36H 25/1200Z 25.4N 95.4W 60 MPH (SW of Brownsville, Texas)
48H 26/0000Z 26.6N 96.3W 75 MPH (SW of Corpus Christi, Texas)
72H 27/0000Z 28.5N 97.5W 50 KT 60 MPH (W of Sarco, Texas)
96H 28/0000Z 28.5N 98.0W 35 KT 40 MPH (E of Ray Point, Texas)
120H 29/0000Z 28.0N 98.0W 30 KT 35 MPH (N of Westdale, Texas)

Previous Warning 700 PM CDT Wed Aug 23 2017

LOCATION…21.7N 92.5W
ABOUT 525 MI SSE OF PORT OCONNOR TEXAS
ABOUT 460 MI SE OF PORT MANSFIELD TEXAS
MAXIMUM SUSTAINED WINDS 35 MPH
PRESENT MOVEMENT…NW OR 320 DEGREES AT 2 MPH
MINIMUM CENTRAL PRESSURE 1003 MB 29.62 INCHES

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Watch is in effect for Port Mansfield to High Island

A Hurricane Watch is in effect for North of Port Mansfield to San Luis Pass

A Tropical Storm Watch is in effect for Boca De Catan Mexico to Port Mansfield Texas,  North of San Luis Pass to High Island

Previous Warning 400 PM CDT Wed Aug 23 2017

High-resolution visible satellite images show that the cloud pattern of Harvey is a little better organized than it was this morning, but the system lacks distinct banding features. Surface synoptic observations, ASCAT data, and Dvorak classifications from TAFB and SAB indicated that the cyclone has not strengthened, so the current intensity is held at 30 kt. The global models predict that an upper-level low over the northwest Gulf of Mexico will essentially dissipate in a day or so.

Therefore, Harvey is expected to remain in a relatively low-shear environment up to the Texas coast. Moreover, ocean analyses show that a warm eddy that broke off from the Loop Current has drifted westward across the Gulf to a location near the projected path of Harvey. This would also be conducive to strengthening, so it is likely that the system will become a hurricane prior to landfall, although this is not explicitly shown in the NHC forecast for which landfall is indicated between 48 and 72 hours.

Based on the scatterometer data and geostationary satellite fixes the center hasn’t moved much this afternoon, although recent imagery suggests a northwestward drift at about 320/2 kt. A weak mid-level ridge to the northeast of Harvey should cause the cyclone to move on a northwestward or north-northwestward track through 48 hours. Later, steering currents weaken as a ridge builds over the southwestern United States and a trough drops down from the Plains. As a result, Harvey should decelerate while making landfall and move very slowly just inland of the coast. Some of the track guidance models, such as the HWRF, have shifted southwestward in comparison to their previous run. The official track forecast is very close to the previous one through 48 hours and is a little slower and to the west after that time. This is very close to the latest dynamical model consensus, TVCN. It should be noted that synoptic surveillance data are currently being collected by the NOAA G-IV jet aircraft and these data will be assimilated into, and hopefully improve the forecasts by, the global models.

Key Messages:

1. Harvey is likely to bring multiple hazards, including heavy rainfall, storm surge, and possible hurricane conditions to portions of the Texas coast beginning on Friday.

2. Heavy rainfall is likely to spread across portions of eastern Texas, Louisiana, and the lower Mississippi Valley from Friday through early next week and could cause life-threatening flooding.

Previous Warning 100 PM  Wed Aug 23 2017 CDT

The center of Tropical Depression Harvey was located near latitude 21.5 North, longitude 92.5 West. The depression has been nearly stationary for the past few hours, but is expected to resume a motion toward the northwest near 9 mph (15 km/h) later today. A track toward the northwest or north-northwest is expected for the next 48 hours. On the forecast track, Harvey should be approaching the Texas coast late Friday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and Harvey could become a hurricane on Friday. The estimated minimum central pressure is 1005 mb (29.68 inches).

HAZARDS AFFECTING LAND
———————-
RAINFALL: Harvey is expected to produce total rain accumulations of 10 to 15 inches with isolated maximum amounts of 20 inches over the middle and upper Texas coast and southwest Louisiana through next Tuesday, with heavy rainfall beginning as early as Friday morning. Harvey is also expected to produce total rain accumulations of 3 to 9 inches in portions of south, central, and northeast Texas and the rest of the lower Mississippi Valley. Rainfall from Harvey could cause life-threatening flooding.

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water is expected to reach the following heights above ground if the peak surge occurs at the time of high tide…

Port Mansfield to High Island…4 to 6 ft

The deepest water will occur along the immediate coast near and to the northeast of the landfall location, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.

Previous Warning 800 AM Wed Aug 23 2017 

Satellite images, reconnaissance data and surface observations indicate that the remnants of Harvey are close to redeveloping into a tropical depression over the southwestern Gulf of Mexico about 150 miles west of Merida, Mexico. Advisories will likely be re-initiated at 10 am CDT on this system. The low is forecast to move to the northwest at about 10 mph across the western Gulf of Mexico, possibly reaching the northwestern Gulf coast late Friday. This system is likely to slow down once it reaches the coast, increasing the threat of a prolonged period of heavy rainfall and flooding across portions of Texas and Louisiana into early next week. Harvey could also produce storm surge and tropical storm or hurricane force winds along portions of the Texas coast later this week, and Tropical Storm or Hurricane Watches could be required later today for portions of the coast of northeastern Mexico, Texas, and southwestern Louisiana. Interests in these areas should monitor the progress of this system and refer to products issued by your local National Weather Service office for more information. Formation chance through 48 hours, high, near 100 percent. Formation chance through 5 days, high, near 100 percent.

Previous Warning 647 AM Wed Aug 23 2017 

As of 23/0900 UTC, a tropical wave extends from 26.5N92W to  17N91W moving NW at 10 kt. The remnant circulation of Harvey  continues to be analyzed as a 1009 mb low pressure along the wave axis over the Bay of Campeche near 21N92W.  Scattered moderate to  isolated strong convection is from 20N-24N between 89W-93W.  tropical depression or tropical storm is very likely to form today or tonight while the low moves northwestward across the western  Gulf of Mexico, possibly reaching the northwestern Gulf coast late Friday. Regardless of development, this system is likely to slow  down once it reaches the coast, increasing the threat of a  prolonged period of heavy rainfall and flooding across portions of Texas, southwestern Louisiana, and northeastern Mexico into early next week. This system could also produce storm surge and  tropical storm or hurricane force winds along portions of the Texas coast later this week, and Tropical Storm or Hurricane  Watches could be required later today for portions of the coast of northeastern Mexico, Texas, and southwestern Louisiana. Interests in these areas should monitor the progress of this system, and  refer to products issued by your local National Weather Service office for more information. An Air Force Reserve reconnaissance aircraft is schedule to investigate the low this morning. A gale  warning has been issued for the SW and west- central Gulf.

Previous Warning 200 AM EDT Tue Aug 23 2017

A broad area of low pressure associated with the remnants of Harvey is located over the eastern Bay of Campeche. Although thunderstorm activity has increased over the northern portion of the system tonight, recent satellite wind data indicate that low pressure area lacks a well-defined circulation at this time. Environmental conditions are conducive for development, and a tropical depression or tropical storm is very likely to form today or tonight while the low moves northwestward at about 10 mph across the western Gulf of Mexico, possibly reaching the northwestern Gulf coast late Friday.

Regardless of development, this system is likely to slow down once it reaches the coast, increasing the threat of a prolonged period of heavy rainfall and flooding across portions of Texas, southwestern Louisiana, and northeastern Mexico into early next week. This system could also produce storm surge and tropical storm or hurricane force winds along portions of the Texas coast later this week, and Tropical Storm or Hurricane Watches could be required later today for portions of the coast of northeastern Mexico, Texas, and southwestern Louisiana. Interests in these areas should monitor
the progress of this system, and refer to products issued by your local National Weather Service office for more information. An Air Force Reserve reconnaissance aircraft is schedule to investigate the low this morning. Formation chance through 48 hours, high, 90 percent. Formation chance through 5 days, high, near 100 percent

Previous Warning 800 PM EDT Tue Aug 22 2017

Satellite images and surface observations indicate that the area of low pressure associated with the remnants of Harvey is moving off the coast of the Yucatan Peninsula into the southern Gulf of Mexico. Environmental conditions are conducive for a tropical depression or tropical storm to form on Wednesday or Thursday while the low moves northwestward at about 10 mph across the western Gulf of Mexico, possibly reaching the northwestern Gulf coast on Friday. Regardless of development, this system is likely to slow down once it reaches the coast, increasing the threat of a prolonged period of heavy rainfall and flooding across portions of Texas, southwestern Louisiana, and northeastern Mexico into early next week. This system could also produce storm surge and tropical storm or hurricane force winds along portions of the Texas coast later this week, and interests from northeastern Mexico to southwestern Louisiana should continue to monitor its progress. Please refer to products from your local National Weather Service office for more information on this system. Formation chance through 48 hours, high, 90 percent. Formation chance through 5 days, high, near 100 percent.

Previous Warning 800 AM EDT Tue Aug 22 2017

Disorganized showers and thunderstorms over the Yucatan Peninsula and adjacent water areas are associated with the remnants of Harvey. Environmental conditions are expected to be conducive for development when the system moves over the Bay of Campeche tonight, and a tropical depression is expected to form over the southwestern Gulf of Mexico on Wednesday or Thursday. Regardless of development, locally heavy rainfall and gusty winds are expected to spread westward across Belize and the Yucatan Peninsula during the next day or so. Interests in northeastern Mexico and along the Texas coast should monitor the progress of this system. Formation chance through 48 hours, high, 70 percent. Formation chance through 5 days, high, 90 percent.

Previous Warning  200 AM EDT Tue Aug 22 2017

 A large area of disturbed weather over the northwestern Caribbean Sea is associated with the remnants of Harvey. Satellite images and surface observations indicate that the system has not become better organized and tropical cyclone development is not expected before the system moves inland over the Yucatan peninsula this morning. However, environmental conditions are expected to beconducive for development when the system moves over the Bay of Campeche tonight or early Wednesday, and a tropical depression is likely to form over the southwestern Gulf of Mexico on Wednesday or Thursday. Regardless of development, locally heavy rainfall and gusty winds are expected to spread westward across Belize and the Yucatan peninsula during the next day or so. Formation chance through 48 hours, high, 70 percent. Formation chance through 5 days, high, 90 percent.

Previous Warning 800 PM EDT Mon Aug 21 2017 

A large area of disturbed weather over the northwestern Caribbean Sea is associated with the remnants of Harvey. Satellite images and surface observations indicate that the system lacks a well-defined circulation and surface pressures are not falling at this time. Although this system could still become better organized while approaching the Yucatan peninsula tonight and early Tuesday, tropical cyclone formation is not expected until the disturbance moves into the Bay of Campeche on Wednesday where conditions are favorable. Regardless of development, locally heavy rainfall and gusty winds are likely to spread westward primarily across Belize and the Yucatan Peninsula during the next couple of days. Formation chance through 48 hours, high, 70 percent. Formation chance through 5 days, high, 90 percent.

Previous Warning 200 PM EDT Mon Aug 21 2017

Shower and thunderstorm activity has increased today in association with the remnants of Harvey, but the system still lacks a well-defined center of circulation. Some development of this disturbance is still possible before it reaches the coast of Belize or the Yucatan Peninsula early Tuesday. The system is forecast to move into the Bay of Campeche early Wednesday, where environmental conditions are expected to be conducive for redevelopment into a tropical cyclone. Regardless of development, locally heavy rainfall and gusty winds are likely to spread westward across Honduras, Belize, and the Yucatan Peninsula during the next couple of days. Formation chance through 48 hours, high, 70 percent.
Formation chance through 5 days, high, 90 percent.

Previous Warning 800 AM AST Mon Aug 21 2017

A trough of low pressure, associated with the remnants of Harvey,continues to produce a large area of disorganized showers and thunderstorms over the northwestern Caribbean Sea. Some development of this system is still possible before it reaches the coast of Belize or the Yucatan Peninsula early Tuesday. The disturbance is forecast to move into the Bay of Campeche early Wednesday, where environmental conditions are expected to be more conducive for redevelopment. Regardless of development, locally heavy rainfall and gusty winds are likely to spread westward across northern Nicaragua, Honduras, Belize, and the Yucatan Peninsula during the next couple of days. The Air Force reconnaissance aircraft mission scheduled for today has been canceled. Formation chance through 48 hours, medium, 50 percent. Formation chance through 5 days, high, 80 percent.

Previous Warning 200 AM AST Mon Aug 21 2017

A trough of low pressure, associated with the remnants of Harvey, is producing a large area of cloudiness and disorganized thunderstorms over the west-central Caribbean Sea. Some development of this system is still possible before it reaches the coast of Belize or the Yucatan Peninsula early Tuesday. The disturbance is forecast to move into the Bay of Campeche early Wednesday, where environmental conditions are expected to be more conducive for redevelopment. Regardless of development, locally heavy rainfall and gusty winds are likely to spread westward across northern Nicaragua, Honduras, Belize, and the Yucatan Peninsula during the next couple of days. Formation chance through 48 hours, medium, 50 percent. Formation chance through 5 days, high, 80 percent.

Previous Warning  800 PM EDT Sun Aug 20 2017

1. Data from an Air Force Reserve Hurricane Hunter mission earlier this afternoon indicated that the remnants of Harvey, located over the central Caribbean Sea, do not have a well-defined center of circulation. In addition, the associated shower and thunderstorm activity remains disorganized and has decreased in coverage and  intensity since earlier in the day. Gradual development of this system is still possible through Monday night while it moves west-northwestward at 15 to 20 mph near the coast of Honduras, and it could become a tropical cyclone again before it reaches the coast of Belize or the Yucatan Peninsula early Tuesday. The remnants are expected to move into the Bay of Campeche on Wednesday, where redevelopment appears more likely due to more favorable upper-level winds. Interests in northern Nicaragua, Honduras, Belize, and the Yucatan Peninsula should monitor the progress of this system. Formation chance through 48 hours, medium, 50 percent. Formation chance through 5 days, high, 80 percent.

Previous Warning 420 PM AST Sun Aug 20 2017

NWS National Hurricane Center Miami FL 420 PM EDT Sun Aug 20 2017 – Special Tropical Weather Outlook issued to update discussion on the remnants of Harvey.

1. Updated: An Air Force Reserve Unit Hurricane Hunter aircraft investigating the remnants of Harvey found that the system still lacks a well-defined center of circulation, and so far there is no indication of winds to tropical storm force. Satellite images indicate that the associated showers and thunderstorms have changed little in organization since earlier today. Gradual development of this system is possible, and it could become a tropical cyclone once again while it moves west-northwestward across the northwestern Caribbean Sea, near the northern coast of Honduras, during the next day or two. The system is expected to reach Belize or the Yucatan Peninsula on Tuesday, and then move into the Bay of Campeche by the middle of the week, where redevelopment appears more likely. Interests in northern Nicaragua, Honduras, Belize, and the Yucatan Peninsula should monitor the progress of this system. Formation chance through 48 hours, medium, 50 percent. Formation chance through 5 days, high, 70 percent.

Previous Warning 200 PM AST Sun Aug 20 2017

1. Satellite images indicate that showers and thunderstorms are showing some signs of organization in association with the remnants of Harvey, but it is still unclear if the system has a closed circulation. Gradual development of this system is possible, and it could become a tropical cyclone once again while it moves west-northwestward across the northwestern Caribbean Sea and the Yucatan Peninsula during the next couple of days, and into the Bay of Campeche by midweek. Interests in northern Nicaragua, Honduras, Belize, and the Yucatan Peninsula should monitor the progress of this system. An Air Force Reserve reconnaissance aircraft is currently enroute and should provide a better assessment of the structure of this system. Formation chance through 48 hour, medium, 50 percent Formation chance through 5 days, high, 70 percent.

Previous Warning 800 AM AST Sun Aug 20 2017

1. Showers and thunderstorms have increased this morning in association with the remnants of Harvey. Gradual development of this system is possible, and it could become a tropical cyclone once again as it moves west-northwestward across the central and northwestern Caribbean Sea during the next couple of days. Interests in northern Nicaragua, Honduras, Belize, and the Yucatan peninsula should monitor the progress of this system. An Air Force Reserve reconnaissance aircraft is scheduled to investigate this disturbance later today. Formation chance through 48 hours, medium, 50 percent. Formation chance through 5 days, medium, 60 percent

Previous Warning 200 AM AST Sun Aug 20 2017

The National Hurricane Center has issued the last advisory on Harvey, which has degenerated into a tropical wave over the central Caribbean Sea.

1. Disorganized showers and thunderstorms over the central Caribbean Sea are associated with the remnants of Harvey. Unfavorable upper-level winds and dry air are expected to inhibit development today. Environmental conditions could become a little more conducive for regeneration by Monday when the system moves west-northwestward over the northwest Caribbean Sea, and interests in northern Nicaragua, Honduras, Belize, and the Yucatan peninsula should monitor the progress of this system. Formation chance through 48 hours…low…30 percent. Formation chance through 5 days…medium…40 percent

Previous Warning 1100 PM AST Sat Aug 19 2017

An Air Force Reserve Hurricane Hunter aircraft investigated Harvey earlier this evening and was unable to close off a center of circulation. The plane found a well-defined wind shift across the wave axis, and winds decreased as the plane flew south along the axis toward a pressure minimum south of 14N. Harvey has therefore degenerated into an open wave, and this will be the last advisory. Maximum surface winds, as measured by the plane, remain 30 kt. As a side note, the associated deep convection has continued to lose organization and is now oriented linearly from northeast to southwest along the wave axis.

Harvey’s remnants are moving quickly westward with a motion of275/19 kt. A fast westward to west-northwestward motion is expected to continue for the next couple of days as the wave moves along the southern periphery of the subtropical ridge. A break in the ridge caused by a mid- to upper-level low over the Gulf of Mexico could cause the system to turn northwestward and slow down as it moves across the Yucatan Peninsula and into the Bay of Campeche in 3-5 days.

The global models, particularly the GFS and ECMWF, deserve a lot of credit for showing Harvey dissipating, or at least not strengthening, over the Caribbean Sea. Even though the vertical shear that has been plaguing the system is expected to diminish in 24-48 hours, the system’s fast motion and ambient dry air will likely keep Harvey’s remnants from regenerating into a tropical cyclone in the near term. For that reason, the solutions shown by
the GFS, ECMWF, and UKMET appear most reasonable, keeping the system as an open wave, or possibly regenerating to a tropical depression before it reaches Belize and the Yucatan coast. Regeneration is also possible if the remnants emerge over the Bay of Campeche.

The remnants of Harvey will be monitored for signs of regeneration and for the possibility of bringing tropical storm conditions to Belize and the Yucatan Peninsula of Mexico during the next couple of days. If necessary, advisories could be resumed and tropical storm watches or warnings issued before Harvey regains tropical cyclone status. Please refer to the Atlantic Tropical Weather Outlook for this system’s potential to regenerate into a tropical cyclone, beginning with the 2 AM issuance on Sunday morning.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0300Z 14.3N 71.8W 30 KT 35 MPH…REMNANTS OF HARVEY (northwest of Aruba)
12H 20/1200Z…DISSIPATED

Previous Warning 1100 AM AST Sat Aug 19 2017

Harvey has become less organized in visible imagery since this time yesterday, with the convective pattern becoming elongated and the circulation looking less well defined. In addition, an Air Force Reserve Hurricane Hunter aircraft could not close the circulation at 850 mb, but was able to close the circulation at 1000 ft. The plane has not yet reported tropical-storm-force winds, but the northwestern quadrant was not well sampled. Thus, the initial intensity is held at a possibly generous 35 kt.

The initial motion is now 275/19. A low- to mid-level ridge extending across the western Atlantic should keep Harvey on a fast westward course across the Caribbean Sea for the next 36-48 hours. Thereafter, there should be a weakness in the ridge north of Harvey caused by a strong mid/upper-level low currently seen in water vapor imagery over the Gulf of Mexico. This pattern should cause a turn toward the west-northwest and a decrease in forward speed. The track guidance is in good agreement that Harvey should pass near or just north of northeastern Honduras, and then cross Belize and/or the Yucatan Peninsula into the Bay of Campeche, and based on this the new forecast track follows the guidance with only minor changes from the previous track.

The ongoing moderate vertical shear should continue for another 12-24 h or so, and combined with the current lack of organization should allow at best only slow strengthening. After that, the upper-level winds are expected to become favorable for strengthening  as the system moves over the deep warm waters of the western Caribbean. The intensity forecast follows the previous forecast in calling for a peak intensity of 60 kt just before the system reaches Belize or the Yucatan Peninsula. Harvey should weaken as it crosses the southern portion of the Yucatan Peninsula between 72-96 h, followed by some re-intensification over the Bay of Campeche. It should be noted that any additional loss of organization in the next
12-24 h would result in the cyclone degenerating into an easterly wave.

FORECAST POSITIONS AND MAX WINDS
12H 20/0000Z 14.1N 70.9W 35 KT 40 MPH (northwest of Aruba)
24H 20/1200Z 14.4N 74.9W 40 KT 45 MPH (north of Colombia)
36H 21/0000Z 14.9N 78.7W 45 KT 50 MPH (northeast of Nicaragua)
48H 21/1200Z 15.7N 82.4W 50 KT 60 MPH (northeast of Honduras)
72H 22/1200Z 17.5N 88.0W 60 KT 70 MPH (east of Belize City, Belize)
96H 23/1200Z 19.0N 91.5W 30 KT 35 MPH (west of Campeche, Mexico)

Previous Warning 500 AM AST Sat Aug 19 2017

GOES-16 shortwave infrared imagery shows the partially exposedcenter of Harvey on the eastern edge of a large area of deep convection. While the center is closer to the convection than a fewhours ago, cirrus clouds be clearly seen moving from northeast tosouthwest across the system; an indication of the persistent shear.Satellite estimates suggest the maximum winds of Harvey remain 35kt.

The storm has picked up some forward speed with a recent motionestimate of 275/18. A low- to mid-level ridge extending across thewestern Atlantic should keep Harvey on a fast westward course across the Caribbean Sea for the next 48 hours. Thereafter, the ridgeweakens across the Gulf of Mexico due to a strong mid/upper-levellow currently seen there on water vapor images. This steering flowchange should cause Harvey to slow down and turn a little more tothe west-northwest in the northwestern Caribbean Sea, with an evenslower motion forecast for Harvey in the Bay of Campeche. Model guidance is in fairly good agreement on this scenario, and nosignificant changes were made to the previous forecast.

Harvey should be moving into a more conducive environment for strengthening early next week since the strong northeasterly shear that has been affecting the cyclone is forecast by almost all of the guidance to weaken within about 24 hours. In a few days, most of the global models show a favorable upper-level environment for intensification, and Harvey could be near hurricane strength between the 72 hour forecast period and landfall. There has been little change to the guidance so the new intensity forecast is similar tothe previous one, close to the model consensus. However, with a weak storm moving so quickly across the central Caribbean, one always has to be careful of the system opening up into a wave. This is a plausible alternative scenario still suggested by the GFS andECMWF models.

FORECAST POSITIONS AND MAX WINDS
12H 19/1800Z 14.0N 68.7W 35 KT 40 MPH (north of Aruba)
24H 20/0600Z 14.3N 72.7W 40 KT 45 MPH (northwest of Aruba)
36H 20/1800Z 14.6N 76.7W 45 KT 50 MPH (northwest of Colombia)
48H 21/0600Z 15.2N 80.1W 50 KT 60 MPH (northeast of Nicaragua)
72H 22/0600Z 17.0N 86.5W 55 KT 65 MPH (north of Honduras)
96H 23/0600Z 18.3N 90.5W 35 KT 40 MPH (Aquada Seca, Mexico)
120H 24/0600Z 19.3N 93.0W 40 KT 45 MPH ( Bay of Campche N ofTabasco Mexico)

Previous Warning 500 PM AST Fri Aug 18 2017

NWS National Hurricane Center Miami FL 500 PM AST Fri Aug 18 2017

Again, there has been little change in the structure of Harvey, with the low-level center near the eastern edge of a strong, but poorly organized, convective area. Earlier reports from an Air Force Reserve Hurricane Hunter aircraft included winds suggesting an increased intensity. However, due to uncertainties in how representative these measurements were, no appreciable change in
the central pressure, and no improvement in the structure, the initial intensity is held at 35 kt.

The initial motion is 275/18. A strong low- to mid-level ridge north of the cyclone should keep Harvey on this general motion for the next 3 days or so, with the system moving from the eastern to the western Caribbean Sea during this time. After 72 h, a west-northwestward motion with a decrease in forward speed is expected when Harvey passes near or over portions of Central America, the Yucatan Peninsula, and eastern Mexico. The new
forecast track is a little faster then the previous track, but there were only minor changes in the direction. It should be noted that there is considerable uncertainty about how far north Harvey might get over the Bay of Campeche, with several of the large-scale models not bringing the center back over the water on the latest runs.

The current shear should persist for about the next 48 h, and thus the intensity forecast continues the trend of slow strengthening during this time. However, the GFS and ECMWF again forecast Harvey to degenerate to an open wave during this time, and the rest of the intensity guidance has trended toward a weaker cyclone. This lowers the confidence in intensification. After 48 h, conditions appear more favorable for strengthening, with the main uncertainty being how much land Harvey will encounter. The intensity forecast will again call for a peak intensity of 60 kt in 72 h, followed by weakening due to land interaction.

12H 19/0600Z 13.6N 65.7W 35 KT 40 MPH (west of St. Vincent and the Grenadines)
24H 19/1800Z 13.9N 69.3W 40 KT 45 MPH (northeast of Aruba)
36H 20/0600Z 14.2N 73.0W 40 KT 45 MPH (northeast of Aruba)
48H 20/1800Z 14.5N 76.7W 45 KT 50 MPH (north of Columbia)
72H 21/1800Z 15.5N 83.5W 60 KT 70 MPH (northeast of Lempera Honduras)
96H 22/1800Z 17.5N 88.5W 50 KT 60 MPH (west of Belize City, Belize)
120H 23/1800Z 19.0N 92.0W 30 KT 35 MPH (north of Ciudad del Carmen, Mexico)

Previous Warning 200 PM AST Fri Aug 18 2017

NWS National Hurricane Center Miami FL 200 PM AST AST Fri Aug 18 2017

The center of Tropical Storm Harvey was located near latitude 13.2 North, longitude 62.1 West. Harvey is moving toward the west near 21 mph (33 km/h) and this general motion is expected to continue for the next couple of days. On the forecast track, the center of Harvey will move away from the Windward Islands and through the eastern Caribbean Sea this afternoon and tonight. It should then move into the central Caribbean Sea on Saturday. Maximum sustained winds are near 40 mph (65 km/h) with highergusts. Slow strengthening is forecast during the next 48 hours. Tropical-storm-force winds extend outward up to 70 miles (110 km) mainly to the north of the center. The minimum central pressure estimated from Air Force Reserve Hurricane Hunter aircraft data is 1005 mb (29.68 inches).

LOCATION…13.2N 62.1W
ABOUT 60 MI…95 KM W OF ST. VINCENT
ABOUT 85 MI…135 KM WSW OF ST. LUCIA
MAXIMUM SUSTAINED WINDS…40 MPH…65 KM/H
PRESENT MOVEMENT…W OR 275 DEGREES AT 21 MPH…33 KM/H
MINIMUM CENTRAL PRESSURE…1005 MB…29.68 INCHES

NWS National Hurricane Center Miami FL 1100 AM AST Fri Aug 18 2017

The structure of Harvey has changed little during the past several hours, and overall the storm is poorly organized. The low-level center is near the eastern edge of the convective mass due to the affects of 15 kt of vertical wind shear. In addition, surface observations and Air Force Reserve Hurricane Hunter data suggest that the 850-mb center is located west or southwest of the surface center. Based on the aircraft and surface data, the central pressure is near 1005 mb and the initial intensity remains 35 kt.

The initial motion is a quick 270/18. A strong low- to mid-level ridge north of the cyclone should keep Harvey on this general motion for the next 3-4 days, with the system moving from the eastern to the western Caribbean Sea during this time. Late in the forecast period, a more northerly motion is expected when Harvey passes near or over portions of Central America, the Yucatan Peninsula, and eastern Mexico. The new forecast track remains in the center of the guidance, and only minor changes were made to the previous track.

The current shear should persist for the next 48 h or so, and thus the intensity forecast continues the trend of slow strengthening during this time. After that, conditions appear favorable for strengthening, with the main uncertainty being how much land Harvey will encounter. The ECMWF keeps the cyclone a little north of Nicaragua and Honduras and allows more room for development, while the GFS forecasts landfall in northeastern Nicaragua and thus has a weaker intensity. The new NHC forecast is close to the previous one in showing a peak intensity below hurricane strength, but the confidence in this portion of the forecast is low.

FORECAST POSITIONS AND MAX WINDS
12H 19/0000Z 13.3N 63.8W 35 KT 40 MPH (west of St. Vincent and the Grenadines)
24H 19/1200Z 13.6N 67.3W 40 KT 45 MPH  (northeast of Curaçao)
36H 20/0000Z 14.0N 71.1W 40 KT 45 MPH (northeast of Aruba)
48H 20/1200Z 14.3N 75.0W 50 KT 60 MPH (north of Columbia)
72H 21/1200Z 15.0N 82.0W 60 KT 70 MPH (east of Nicaragua)
96H 22/1200Z 16.5N 87.5W 55 KT 65 MPH (east of Belize)
120H 23/1200Z 18.5N 91.0W 30 KT 35 MPH (near Escárcega, Mexico)

Previous Warning 500 AM AST Fri Aug 18 2017

Harvey’s cloud pattern has changed very little in organization during the past several hours. The low-level center is difficult to find even using the 1-min images from GOES 16, but it appears to be located on the eastern edge of the convection due to the prevailing easterly shear. Dvorak estimates from both TAFB and SAB support keeping the intensity at 35 kt. Another Air Force plane will be investigating Harvey at sunrise.

The moderate easterly shear affecting the cyclone is expected to increase a little during the next day or so, and this factor should not allow significant strengthening. Once the cyclone reaches the western Caribbean Sea in 3 or 4 days, an environment of lower shear and high moisture is forecast to prevail, and Harvey should then gather some strength. The cyclone could be near hurricane strength by the time it is approaching Central America or the Yucatan peninsula. The NHC forecast is very similar to the previous one and is very close to the intensity consensus. The GFS and the ECMWF
global models are just a little more enthusiastic in keeping the cyclone from dissipating in this last run, but who knows what they
might forecast the next time.

Harvey has not changed in track or speed, and it is still moving toward the west or 270 degrees at 16 kt. The cyclone is well embedded within the easterlies south of a persistent subtropical ridge. This steering pattern will keep Harvey trapped in the Caribbean Sea while moving westward for the next few days. The track forecast is similar to the one issued by my predecessor and it follows closely the multi-model consensus. The guidance envelope is quite tight and is bounded by the northernmost ECMWF and the GFS to
the south.

FORECAST POSITIONS AND MAX WINDS
12H 18/1800Z 13.2N 61.7W 35 KT 40 MPH (west of St. Vincent and the Grenadines)
24H 19/0600Z 13.5N 65.2W 40 KT 45 MPH  (west of St. Vincent and the Grenadines)
36H 19/1800Z 13.9N 68.8W 40 KT 45 MPH (north of Caracas, Venezuela
48H 20/0600Z 14.1N 72.7W 50 KT 60 MPH (north of Curaçao)
72H 21/0600Z 15.0N 80.2W 60 KT 70 MPH (north of Nicaragua)
96H 22/0600Z 16.5N 86.5W 60 KT 70 MPH (east of Belize)

Previous Warning 1100 PM AST Thur Aug 17 2017

“Since an Air Force Hurricane Hunter aircraft departed the storm a few hours ago, the cloud pattern of Harvey hasn’t changed much. Dvorak intensity estimates from both TAFB and SAB are 30 kt, and based on the earlier aircraft measurements the current intensity is held at 35 kt. The storm is in a moderate easterly shear environment, which should allow only slow strengthening for the next couple of days. After that, the dynamical models indicate that a decrease in shear should occur. As noted earlier, however, the GFS and ECMWF global models do not show strengthening of Harvey and in fact practically dissipate it during the forecast period. This suggests something unfavorable in the environment besides shear ahead of the system, perhaps some drier air or subsidence. The official intensity forecast shows modest strengthening and is generally close to the model consensus which includes the statistical/dynamical guidance and the regional hurricane models (that do show some strengthening).

The motion continues westward or 270/16. There is no change to the track forecast philosophy from the previous advisory package. Harvey should remain embedded in the flow on the south side of a strong mid-level ridge throughout most of the forecast period, which should steer the system on a continued westward track. Near the end of period, the guidance suggests a slightly more northward motion with some deceleration. The official forecast track is near the dynamical model consensus and very close to the previous NHC track.”

FORECAST POSITIONS AND MAX WINDS

12H 18/1200Z 13.2N 59.9W 35 KT 40 MPH (Barbados)
24H 19/0000Z 13.6N 63.3W 40 KT 45 MPH (St. Vincent and the Grenadines)
36H 19/1200Z 13.9N 67.0W 45 KT 50 MPH (North of Caracas, Venezuela)
48H 20/0000Z 14.1N 70.9W 50 KT 60 MPH (North of Aruba)
72H 21/0000Z 14.8N 78.6W 60 KT 70 MPH (east of Nicaragua)
96H 22/0000Z 16.0N 85.5W 60 KT 70 MPH (North of Limon, Honduras)
120H 23/0000Z 17.5N 89.0W 55 KT 65 MPH (West of Belize City, Belize)

PREVIOUS WARNING – 800 PM AST Thur Aug 17 2017

At 800 PM AST (0000 UTC), the center of Tropical Storm Harvey was located near latitude 12.9 North, longitude 56.5 West. 

LOCATION…12.9N 56.5W
ABOUT 205 MI…325 KM E OF BARBADOS
ABOUT 310 MI…495 KM E OF ST. LUCIA
MAXIMUM SUSTAINED WINDS…40 MPH…65 KM/H
PRESENT MOVEMENT…W OR 270 DEGREES AT 18 MPH…30 KM/H
MINIMUM CENTRAL PRESSURE…1005 MB…29.68 INCHEs

Harvey is moving toward the west near 18 mph (30 km/h), and this motion is expected to continue for the next couple of days. On the forecast track, Harvey should move through the Windward Islands and into the eastern Caribbean Sea on Friday.

Reports from an Air Force Reserve Hurricane Hunter Aircraft indicate that maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Slow strengthening is possible during the next 48 hours.

Tropical-storm-force winds extend outward up to 35 miles (55 km) to the north of the center.

The latest minimum central pressure reported by the Hurricane Hunter aircraft is 1005 mb (29.68 inches).

HAZARDS AFFECTING LAND

WIND: Tropical storm conditions are expected to first reach the Lesser Antilles within the warning area by early Friday, making outside preparations difficult or dangerous. Tropical storm conditions are possible in the watch area on Friday.

RAINFALL: Harvey is expected to produce rainfall totals of 2 to 4 inches across portions of the Windward Islands from Martinique southward to Grenada. These rains could cause life-threatening flash floods and mudslides.

PREVIOUS WARNING –  500 PM AST Thur Aug 17 2017

Tropical Storm Harvey NWS National Hurricane Center Miami FL 500 PM  Thu Aug 17 2017 (see video below)

An Air Force Reserve Hurricane Hunter aircraft found a well-defined circulation in the low pressure area east of the Lesser Antilles, with the center near a cluster of sheared, but strong, convection. The aircraft data suggest that the maximum winds are near 35 kt and that the central pressure is near 1004 mb. Based on these data, the disturbance is upgraded to Tropical Storm Harvey.

The initial motion is 270/16. There is no change to the forecast philosophy since the previous advisory. A deep-layer ridge to the north of the system should steer it quickly just north of due west through the forecast period, with this motion expected to bring the system through the Lesser Antilles and into the eastern CaribbeanSea in 12-24 h, into the central Caribbean by 48-72 h, and to the western Caribbean by 96-120 h.

One adjustment is that the 96-120 h points have been nudged a little southward in response to a shift in the guidance, and thus now lie closer to Central America than on the previous forecast. The forecast track again lies near the center of the tightly clustered guidance envelope and the various consensus models.

The system is in an area of moderate easterly vertical shear, and the large-scale models suggest that light/moderate shear should continue through at least 72 h. The conflicting forecast scenarios alluded to in the previous advisory remain, with the SHIPS and LGEM models still showing steady intensification while the GFS and ECMWF models still forecast degeneration to an easterly wave over the central Caribbean. The new intensity forecast again follows the trend of the SHIPS/LGEM models, but it remains on the low side of the guidance envelope out of respect for the GFS/ECMWF. The 96-120 h intensities have been decreased a little due to the forecast track showing more land interaction.

FORECAST POSITIONS AND MAX WINDS

12H 18/0600Z 13.1N 58.3W 35 KT 40 MPH (Barbados
24H 18/1800Z 13.4N 61.6W 40 KT 45 MPH (St. Vincent and the Grenadines)
36H 19/0600Z 13.7N 65.1W 45 KT 50 MPH
48H 19/1800Z 14.0N 68.8W 45 KT 50 MPH (NE of Aruba)
72H 20/1800Z 14.5N 76.5W 55 KT 65 MPH (N of Columbia)
96H 21/1800Z 15.5N 83.5W 60 KT 70 MPH (Nicaragua)
120H 22/1800Z 17.0N 88.5W 55 KT 65 MPH (Nicaragua)

Video: Tropical Storm Harvey makes landfall in Louisiana