Potential Tropical Cyclone 10

Atlantic Tropical Weather Update 1100 Hours August 29 2017
Atlantic Tropical Weather Update 1100 Hours August 29 2017
AtlanticTropical Storm Satellite 2100 Hours August 29 2017
AtlanticTropical Storm Satellite 2100 Hours August 29 2017

Potential Tropical Cyclone 10 NWS National Hurricane Center Miami FL 500 PM EDT Tue Aug 29 2017

(See 11:00 AM video below)

Visible satellite images indicate that a more well-defined circulation has begun to form east of the Outer Banks, and surface observations indicate that pressures are falling. The low is becoming extratropical, and there is no longer a possibility of it becoming a tropical cyclone. In addition, the associated tropical-storm-force winds that have been occurring to the southeast of the center are limited to marine areas, so this will be the last NHC advisory on this system. Maximum winds are estimated to be 40 kt to the southeast of the center.

Baroclinic influences are expected to cause the low to deepen as an extratropical cyclone during the next day or two, and it is forecast to produce sustained hurricane-force winds over the northwestern Atlantic by late Wednesday. Gradual weakening is forecast after 36 hours, and the cyclone is likely to be absorbed by another extratropical system over the north Atlantic by day 5.

The low continues to accelerate toward the northeast with an initial motion of 050/21 kt, and it should move even faster toward the northeast or east-northeast across the north Atlantic through day 4, embedded in the mid-latitude westerlies. The track, intensity, and wind radii forecasts incorporate guidance provided by NOAA’s Ocean Prediction Center.

Strong winds on the northern and western side of a frontal boundary associated with the low are expected to affect portions of the mid-Atlantic coast. As a result, high wind warnings are in effect for coastal sections of northeastern North Carolina, southeastern Virginia, and the eastern shore of Virginia and Maryland through  this evening.

This is the last advisory issued by NHC.

12H 30/0600Z 37.6N 70.7W – 50 MPH (E of Maryland)
24H 30/1800Z 39.3N 65.6W – 70 MPH (E of New Jersey)
36H 31/0600Z 40.9N 60.0W – 80 MPH (E of New York)
48H 31/1800Z 42.8N 54.5W – 65 MPH (SE of Nova Scotia Canada)
72H 01/1800Z 47.4N 41.3W – 50 MPH (E of Newfoundland, Canada)
96H 02/1800Z 52.0N 25.5W – 40 MPH (W of Ireland)

Previous Warning 1100 AM EDT Tue Aug 29 2017

Surface observations near and offshore the southern coast of North Carolina indicate that an elongated circulation and pressure minimum are located over Onslow Bay, but satellite imagery still shows no signs of a well-defined center. In addition, a sharp wind shift, associated with a front, extends northeastward across Pamlico and Albemarle Sounds and the Outer Banks. Maximum winds remain 35 kt for continuity’s sake since there have been no recent observations of sustained tropical-storm-force winds.

The disturbance has so far failed to become a tropical cyclone, and since vertical shear is 30-40 kt and increasing, it appears that it now has a low chance of doing so before it becomes extratropical later today. Baroclinic energy from the approaching shortwave trough should cause the extratropical cyclone to strengthen significantly during the next day or two, and it is forecast to be producing hurricane-force winds over the northwestern Atlantic by 36 hours. Gradual weakening is expected after that time until the cyclone is absorbed on day 5.

The disturbance is accelerating toward the northeast with an initial motion of 045/15 kt, and it is likely to clear the Outer Banks into the western Atlantic by late this afternoon. The system is embedded in the mid-latitude westerlies, and it will be interacting with a shortwave trough moving east of the Great Lakes during the next couple of days. This will cause the disturbance to continue accelerating toward the northeast or east-northeast over
the north Atlantic for the next 4 days. The cyclone is expected to be absorbed by another extratropical low by day 5.

Previous Warning  800 AM EDT Tue Aug 29 2017

At 800 AM EDT (1200 UTC), the disturbance was centered near latitude 34.1 North, longitude 77.7 West. The system is moving faster toward the northeast near 15 mph (24 km/h) and is anticipated to accelerate east-northeastward during the next couple of days. The expected track will take the system along the North Carolina coast today before moving out to sea tonight.

Maximum sustained winds remain near 40 mph (65 km/h) with higher gusts. The disturbance is not expected to change much in strength today, and the chances for the system to become a tropical cyclone appear to be decreasing.

Regardless of whether or not this system becomes a tropical cyclone, tropical-storm-force winds and heavy rains are expected over portions of North Carolina later today. Formation chance through 48 hours, medium, 40 percent. Formation chance through 5 days, medium, 40 percent

Previous Warning  500 AM EDT Tue Aug 29 2017

The disturbance has developed a center that has been trackable this evening though it is still not well-defined, since it appears to be considerably elongated northeast-southwest. The disturbance continues to display very cold, but extremely asymmetric deep convection with all of the thunderstorm activity east of the center due to strong vertical shear. Moreover, the convection is showing no identifiable banding features. So the system is not yet a tropical cyclone. Regardless of the label we use to describe this hybrid system, maximum winds are around 35 kt based upon a Dvorak classification from TAFB and observed winds just below that from the NDBC Buoy 41013.

The initial motion of the disturbance is northeast at a faster rate of about 10 kt. Continued acceleration is expected during the next couple of days as a mid- to upper-level trough over the Great Lakes moves closer to the system. The NHC forecast track takes the disturbance across the North Carolina coastline today. By tonight, the cyclone is forecast to move offshore and accelerate over the Atlantic in the mid-latitude westerlies. The NHC track forecast lies near the middle of the guidance envelope and is not substantially changed from the previous advisory.

Given the poor organization of the disturbance and the strong wind shear environment that it is embedded within, the chances of this disturbance becoming a tropical cyclone have decreased to about a coin flip. Nonetheless, the potential impacts of tropical-storm- force winds across portions of North Carolina are likely today even if the system does not become a tropical cyclone. The system is expected to become extratropical in 24 hours or less when it interacts with the aforementioned mid- to upper-level trough. Significant strengthening as an extratropical cyclone is forecast for a couple of days due to baroclinic forcing. No significant change has been made to the NHC intensity forecast.

The track, intensity, and wind radii forecasts from 24 to 120 h are based on guidance provided by NOAA’s Ocean Prediction Center.

12H 29/1800Z 35.4N 76.0W – 45 MPH (NW of Hatteras, NC)
24H 30/0600Z 38.0N 71.5W – 60 MPH (SE of Ocean City, MD)
36H 30/1800Z 39.5N 66.5W – 70 MPH (NE of Atlantic City, NJ)
48H 31/0600Z 41.0N 61.0W – 80 MPH (NE of New York)
72H 01/0600Z 44.5N 50.0W – 60 MPH (E of Nova Scotia, Canada)
96H 02/0600Z 50.0N 33.0W – 45 MPH (SW of Ireland)
120H 03/0600Z 55.0N 19.0W – 35 MPH (NW of Ireland)

Previous Warning 1100 PM EDT Mon Aug 28 2017

Although the disturbance continues to produce a fairly large area of deep convection, this activity is far from the estimated center and the circulation remains poorly defined. Surface observations and radar data suggest that the circulation of the system is stretched from north-northeast to south southwest, and the position used in this advisory is near the estimated minimum pressure location. The initial intensity remains 35 kt based on the earlier aircraft data and a Dvorak classification from TAFB.

Since the system does not have a clear center, the initial motion is an uncertain 020/6 kt. A faster northeastward motion is expected to begin overnight or early Tuesday as a mid- to upper-level trough over the Great Lakes moves closer to the system. The NHC forecast track takes the disturbance across the South Carolina and North Carolina coastline overnight and on Tuesday. By late Tuesday, the cyclone is forecast to move offshore and accelerate over the Atlantic in the mid-latitude westerlies. The NHC track forecast lies near the middle of the guidance envelope.

Given the poor organization of the disturbance and the strong wind shear environment that it is embedded within, the chances of this disturbance becoming a tropical cyclone appear to be decreasing. Nonetheless, the potential impacts of tropical-storm-force winds and heavy rains across portions of the Carolinas are likely tonight and on Tuesday even if the system does not become a tropical cyclone. The system is expected to become post-tropical in about 24 hours when it interacts with the aforementioned mid- to upper-level trough. Significant strengthening as an extratropical cyclone is forecast for a couple of days due to baroclinic forcing.

The track, intensity, and wind radii forecasts from 36 to 120 h are based on guidance provided by NOAA’s Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 32.5N 80.0W – 40 MPH (SE of Kiawah Island, SC)
12H 29/1200Z 34.5N 77.6W – 40 MPH (NW of Surf City, NC)
24H 30/0000Z 36.9N 73.7W – 50 MPH (E of Virginia Beach, VA)
36H 30/1200Z 39.0N 69.1W – 65 MPH (SE of Atlantic City,  NJ)
48H 31/0000Z 40.5N 64.0W – 80 MPH (E of New York City, NY)
72H 01/0000Z 43.8N 53.1W – 65 MPH (E of Nova Scotia, Canada)
96H 02/0000Z 48.5N 39.0W – 50 MPH (E of Newfoundland, Canada)
120H 03/0000Z 53.0N 23.0W – 40 MPH (W of  Ireland)

Resources:

Previous Warning 500 PM EDT Mon Aug 28 2017

An Air Force Hurricane Hunter plane has been flying through the disturbance and so far the aircraft data depicts a sharp trough with a few spots of tropical-storm-force winds east of the trough axis. The overall cloud pattern has not become any better organized, and most of the weather is located in bands well to the northeast and southeast of the trough. With the shear increasing, the chances for the system to become a tropical storm are diminishing, but if it does occur it should happen within the next 24 hours or so while the system moves near the Outer Banks of North Carolina. Regardless of whether tropical cyclone formation occurs, tropical storm conditions are still expected in the warning area in North Carolina. Beyond 24 hours, the system should acquire extratropical characteristics. However, the exact timing of the transition is uncertain since the cyclone will still be moving over
warm waters.

In reality, we can not track a center of circulation that does not exist and NHC is following an area of minimum pressure. This makes the initial motion highly uncertain and the best estimate is toward the northeast or 040 degrees at 10 kt. The system is already embedded within the mid-latitude southwesterly flow ahead of a trough, and this pattern will steer the disturbance toward the northeast with a gradual increase in forward speed.

12H 29/0600Z 33.4N 78.7W – 40 MPH (E of Georgetown, SC)
24H 29/1800Z 35.6N 75.7W – 40 MPH (SE of Stumpy Point, NC)
36H 30/0600Z 38.0N 71.5W – 45 MPH (E of Ocean City, MD)
48H 30/1800Z 40.0N 66.5W – 65 MPH (E of New York City)
72H 31/1800Z 43.0N 56.0W – 70 MPH (E of Nova Scotia, Canada)
96H 01/1800Z 47.0N 44.0W  – 60 MPH (E of St. Johns Newfoundland)
120H 02/1800Z 51.6N 28.5W – 45 MPH (W of Ireland)

Previous Warning 200 PM EDT Monday Aug 28 2017

At 200 PM EDT (1800 UTC), the elongated area of low pressure associated with the disturbance was centered near latitude 31.8 North, longitude 80.3 West. The system is moving toward the north near 9 mph (15 km/h), and a gradual turn to the north- northeast and northeast with a gradual increase in forward speed are expected during the next couple of days. On the forecast track, the system will move over or near the coast of South Carolina today and move along the North Carolina Outer Banks on Tuesday.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. These winds are occuring over water well to the east of the broad area of low pressure. Although the disturbance has not shown any significant increase in organization today, conditions still favor the system becoming a tropical storm later today or Tuesday. An Air Force plane is currently investigating the disturbance. Formation chance through 48 hours, high, 80 percent. Formation chance through 5 days, high, 80 percent.

Previous Warning 800 AM EDT Sun Aug 27 2017

At 800 AM EDT (1200 UTC), the poorly defined circulation associated with the disturbance was estimated near latitude 31.0 North, longitude 80.7 West. The system has been moving little, and a slow and erratic motion is forecast through this afternoon, followed by a faster northeastward motion tonight and Tuesday. On the forecast track, the system will move near the Georgia and South Carolina coasts later today and move along the North Carolina coast on Tuesday.

Maximum sustained winds remain near 35 mph (55 km/h) with higher gusts. Some strengthening is possible during the next 48 hours, and the system is expected to become a tropical storm by Tuesday morning and then become post-tropical by Tuesday night.

Although satellite and radar data indicate that the associated showers and thunderstorms show some signs of organization, the center of circulation is not yet well defined. Only a slight increase in the definition of the circulation would lead to the formation of a tropical cyclone.

RAINFALL: The system is expected to produce total rain accumulations of 3 to 6 inches along the upper South Carolina, North Carolina, and southeast Virginia coasts, with possible isolated maximum amounts of 9 inches. The heavier rains may result in some flooding concerns along coastal areas.

SURF: Swells generated by this disturbance will affect portions of the Georgia, South Carolina, and North Carolina coasts during the next day or two, creating dangerous surf and rip current conditions. Please consult products from your local weather office.

Formation chance through 48 hours, high, 90 percent. Formation chance through 5 days, high, 90 percent.

Previous Warning 1100 PM EDT Sun Aug 27 2017

Deep convection has been increasing in both intensity and coverage during the past several hours in association with Potential Tropical Cyclone Ten. However, satellite and radar data indicate that the circulation remains poorly defined, therefore, the system is not yet a tropical cyclone. The initial intensity is held at 30 kt based on the surrounding surface observations and the earlier ASCAT data.

The disturbance is located in weak steering currents, and has been meandering during the last several hours. A continued slow and erratic motion is likely to continue overnight and early Monday. A mid- to upper-level trough currently over the central U.S. is expected to approach the system, and should cause the disturbance to begin moving northeastward by late Monday. A faster east- northeastward to northeastward motion is forecast thereafter when the system becomes embedded in the mid-latitude westerlies. The models are in fair agreement, and only small changes were made to the previous NHC track forecast. This forecast takes the center of the disturbance near the Georgia and South Carolina coasts tonight and Monday and along the North Carolina coastline Monday night and Tuesday.

The elongated center of the disturbance is located to the west of the main area of deep convection due to strong westerly vertical wind shear. The shear is only expected to lessen a little during the next 12 to 24 hours, but it will likely weaken enough to allow the system to become a tropical cyclone. After that time, increasing shear and interaction with the aforementioned trough should cause the disturbance to lose its tropical characteristics in about 48 hours. Strengthening is likely for a couple of days while the system is post-tropical due to baroclinic effects.

Although the potential for tropical storm winds are within the warning time period (36 hours), given the uncertainty in whether these winds will occur on land in northeastern South Carolina and southeastern North Carolina, a tropical storm watch remains in effect for those areas. Note that north of Duck, North Carolina, hazards from this system will be handled with non-tropical products issued by local National Weather Service offices.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 30.5N 80.8W – 35 MPH (NE of Jacksonville, Fl)
12H 28/1200Z 30.9N 81.0W – 40 MPH (SE of Brunswick, Georgia)
24H 29/0000Z 32.3N 79.9W – 40 MPH (NE of Hilton Head Island, South Carolina)
36H 29/1200Z 34.4N 77.5W – 40 MPH (Surf City, North Carolina)
48H 30/0000Z 36.5N 73.8W – 50 MPH (SE of Virginia Beach, Virginia)
72H 31/0000Z 39.9N 64.2W – 65 MPH (E of Philadelphia, Pennsylvania)
96H 01/0000Z 43.2N 53.4W – 70 MPH (E of Portland, Maine)
120H 02/0000Z 47.2N 41.1W – 50 MPH 9 (E of Newfoundland, Canada)

Previous Warning 800 PM EDT Sun Aug 27 2017

DISTURBANCE NEARLY STATIONARY OFF THE SOUTHEAST U.S. COAST…
LOCATION…30.9N 80.3W
ABOUT 135 MI…220 KM SSW OF CHARLESTON SOUTH CAROLINA
ABOUT 270 MI…435 KM SSW OF WILMINGTON NORTH CAROLINA
MAXIMUM SUSTAINED WINDS…35 MPH…55 KM/H
PRESENT MOVEMENT…STATIONARY
MINIMUM CENTRAL PRESSURE…1007 MB…29.74 INCHES

At 800 PM EDT (0000 UTC), the disturbance was centered near latitude 30.9 North, longitude 80.3 West. The system is currently stationary. A slow northward motion is expected overnight and Monday, followed by a faster northeastward motion Monday night and Tuesday. On the forecast track, the system will move slowly offshore of the South Carolina coast tonight and Monday, and then move along or near the northeastern coast of South Carolina and the North Carolina coast Monday night and Tuesday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and the system is expected to become a tropical storm later tonight or Monday. The disturbance is expected to become post-tropical on Tuesday.

Satellite and radar data indicate that the associated showers and thunderstorms continue to be well organized, but the center of circulation is not yet well defined. Only a slight increase in the definition of the circulation would lead to the formation of a tropical cyclone.
Formation chance through 48 hours, high, 90 percent Formation chance through 5 days, high, 90 percent

The estimated minimum central pressure based on buoy data is 1007 mb (29.74 inches).

Previous Warning 500 PM EDT Sun Aug 27 2017

At 500 PM EDT (2100 UTC), the disturbance was centered near latitude 31.2 North, longitude 80.0 West. The system is currently stationary. A slow northward motion is expected tonight and Monday, followed by a faster northeastward motion Monday night and Tuesday.

On the forecast track, the system will move slowly toward the South Carolina coast tonight and Monday. The system is forecast to move near the northeastern coast of South Carolina and along the North Carolina coast Monday night and Tuesday.

Satellite wind data and buoy observations indicate that maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and the system is expected to become a tropical storm tonight or Monday. The system is expected to become post-tropical on Tuesday.

Shower and thunderstorm activity has increased in coverage and gradually become better organized, and the low is likely to become a tropical depression or tropical storm in the next day or so. Formation chance through 48 hours, high, 70 percent. Formation chance through 5 days, high, 70 percent

The estimated minimum central pressure based on buoy data is 1007 mb
(29.74 inches).

Potential Tropical Cyclone 10 is expected to produce heavy rainfall. Amounts of 2 to 4 inches with localized rainfall amounts of up to 6 inches are possible, which may cause flooding of low-lying areas.

Minor inundation impacts of 1 to 2 feet are expected along areas adjacent to Pamlico and Albemarle Sounds, lower Neuse River and from
Core Sound to the Beaufort area.

There will be a high threat of rip currents along all area beaches along with rough surf with breaking waves 6 to 9 feet that could
result in minor erosion and overwash. It is recommended to avoid swimming.

LOCATION…31.2N 80.0W
ABOUT 110 MI…180 KM S OF CHARLESTON SOUTH CAROLINA
ABOUT 245 MI…390 KM SSW OF WILMINGTON NORTH CAROLINA
MAXIMUM SUSTAINED WINDS…35 MPH…55 KM/H
PRESENT MOVEMENT…STATIONARY
MINIMUM CENTRAL PRESSURE…1007 MB…29.74 INCHES

Previous Warning 800 AM EDT Sun Aug 27 2017

The National Hurricane Center is issuing advisories on Tropical Storm Harvey, located inland over southeastern Texas.

1. An elongated area of low pressure located over northeast Florida is producing a widespread area of disorganized showers and thunderstorms. This system is expected to move over the western Atlantic later today, and has a brief opportunity to become a tropical or subtropical depression during the next day or so, before it merges with a cold front. Regardless of development, the low is expected to cause increasing winds and rough surf along the coasts of Georgia, the Carolinas, and Virginia through mid-week. Heavy rain is also expected to continue over portions of the Florida peninsula during the next 24 hours. Please refer to products from your local National Weather Service forecast office for more information on this system. Formation chance through 48 hours, medium, 40 percent. Formation chance through 5 days, medium, 50 percent.

2. A tropical wave over western Africa is forecast to emerge over the far eastern Atlantic Ocean tonight or early Monday. Environmental conditions appear to be conducive for slow development by the middle of next week while the wave moves westward about 15 to 20 mph. Formation chance through 48 hours, low, near 0 percent. Formation chance through 5 days, low, 20 percent.

If this disturbance becomes a tropical storm it will be named Irma.

Previous Warning 800 PM EDT Sat Aug 26 2017

The National Hurricane Center is issuing advisories on Tropical Storm Harvey, located inland over central Texas.

An elongated area of low pressure stretching across north-central Florida continues to produce a large area of disorganized cloudiness and thunderstorms extending from the southwest coast of Florida northeastward into the western Atlantic. Although upper-level winds are not particularly conducive, this system has the potential to become a tropical or subtropical depression early next week after it moves off the northeast coast of Florida on Sunday. The low is forecast to move close to the southeastern coast of the United States and merge with a cold front by mid-week. Regardless of tropical cyclone development, the low is expected to cause increasing winds and rough surf along the coasts of Georgia and the Carolinas through early next week. Heavy rain is also expected to continue over portions of the Florida peninsula during the next day or two.  Formation chance through 48 hours, medium, 40 percent. Formation chance through 5 days, medium, 50 percent.

A tropical wave over western Africa is forecast to emerge over the far eastern Atlantic Ocean on Sunday. Environmental conditions may
be conducive for slow development by the middle of next week while the wave moves westward about 20 mph. Formation chance through 48 hours, low, near 0 percent. Formation chance through 5 days, low, 20 percent.

Previous Warning 200 PM EDT Sat Aug 26 2017

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on recently downgraded Tropical Storm Harvey, located inland over eastern Texas.

1. An elongated area of low pressure stretching across north-central Florida continues to produce a large area of disorganized cloudiness and thunderstorms extending from the southwest coast of Florida northeastward into the western Atlantic. Although upper-level winds are not particularly conducive, this system has the potential to become a tropical or subtropical depression early next week after it moves off the northeast coast of Florida on Sunday. The low is forecast to move close to the southeastern coast of the United States and merge with a cold front by mid-week. Regardless of tropical cyclone development, the low is expected to cause increasing winds and rough surf along the coasts of Georgia and the Carolinas through early next week. Heavy rain is also expected to continue over portions of southern and central Florida during the next day or two.  Formation chance through 48 hours, medium, 40 percent. Formation chance through 5 days, medium, 50 percent.

2. A tropical wave over western Africa is forecast to emerge over the far eastern Atlantic Ocean on Sunday. Environmental conditions are forecast to be conducive for slow development by the middle of next week while the wave moves westward about 20 mph. Formation chance through 48 hours, low, 0 percent. Formation chance through 5 days, low, 20 percent.

Previous Warning  200 AM EDT Sat Aug 26 2017

1. A broad area of low pressure continues to produce a large area of disorganized cloudiness and thunderstorms over southern and central Florida and the adjacent waters. Some development is possible through early next week while this system moves over the western Atlantic, before it merges with a front. Regardless of development, heavy rain and flooding is possible over portions of southern and central Florida, and the northwestern Bahamas during the next few days. In addition, this system is expected to cause increasing northeast winds and rough surf along the coast of Georgia and the Carolinas through early next week. Please refer to products from your local weather office for more information on this system. Formation chance through 48 hours, low, 30 percent. Formation chance through 5 days, medium, 50 percent.

Previous Warning 420 PM EDT Sun Aug 20 2017

Special Tropical Weather Outlook issued to update discussion on the remnants of Tropical Storm Harvey

2. Satellite data indicate that a trough of low pressure located a couple of hundred miles north of the Dominican Republic is producing disorganized showers and thunderstorms, with some strong winds on its northeast side. Environmental conditions are expected to be unfavorable for development of this system during the next day or two, but they could become slightly more conducive for development by midweek when the system is near the northwestern Bahamas or Florida. This system is expected to move west-northwestward at 15 to 20 mph during the next few days. Formation chance through 48 hours, low, 10 percent. Formation chance through 5 days, low, 30 percent.

Previous Warning 200 PM AST Sat Aug 19 2017

The National Hurricane Center is issuing advisories on Tropical Storm Harvey, located over the central Caribbean Sea. Tropical Storm Harvey (left circle) and potential Tropical Storm Irma (right circle), both located in the Caribbean.

1. A trough of low pressure located about 250 miles north-northeast of the northern Leeward Islands continues to produce disorganized showers and thunderstorms. Environmental conditions are expected to be unfavorable for development during the next couple of days while the system system moves west-northwestward at about 20 mph. Conditions may become a little more conducive early next week while
the system is near the Bahamas. Formation chance through 48 hours, low, 10 percent. Formation chance through 5 days, low, 30 percent.

2. A tropical wave located over the eastern Atlantic Ocean about midway between the Lesser Antilles and Africa is producing some shower and thunderstorm activity. Environmental conditions appear somewhat conducive for gradual development over the next day or two while the system moves west-northwestward to northwestward at about 20 mph, but upper-level winds are forecast to become unfavorable by early next week. Formation chance through 48 hours…low…10 percent. Formation chance through 5 days, low, 10 percent.

Previous Warning 800 AM EDT Sat Aug 19 2017

National Weather Service National Hurricane Center is issuing warnings on Tropical Storm Harvey. Tropical Storm Harvey (left circle) and potential Tropical Storm Irma (right circle), both located in the Caribbean.

There are two other areas as well as Harvey  we are watching.

1. A trough of low pressure located about 300 miles east-northeast of the northern Leeward Islands continues to produce disorganized showers and thunderstorms. Environmental conditions are expected to be only marginally conducive for development during the next few days while this system moves west-northwestward at about 20 mph. Formation chance through 48 hours, low, 20 percent. Formation chance through 5 days, medium, 40 percent.

2. A tropical wave located over the eastern Atlantic Ocean about midway between the Lesser Antilles and Africa is producing some shower and thunderstorm activity. Environmental conditions appear somewhat conducive for gradual development over the next few days while the system moves west-northwestward to northwestward at about 20 mph, but upper-level winds are forecast to become unfavorable by early next week. Formation chance through 48 hours, low, 10 percent. Formation chance through 5 days, low, 20 percent.

Previous Warning 800 PM

NWS National Hurricane Center Miami FL 800 PM EDT Fri Aug 18 2017

We are watching two storm systems at this time. Tropical Storm Harvey (left circle) and potential Tropical Storm Irma (right circle), both located in the Caribbean.

The National Hurricane Center is issuing advisories on Tropical Storm Harvey, located over the eastern Caribbean Sea.

1. Showers and thunderstorms associated with an area of disturbed weather located about 500 miles east-northeast of the northern Leeward Islands have become less organized since yesterday due to strong upper-level winds, and satellite data suggest that the surface circulation has become less defined. Environmental conditions are expected to be only marginally conducive for development during the next couple of days while this system moves west-northwestward at about 20 mph, and the chances for tropical cyclone formation appear to be decreasing. Formation chance through 48 hours, medium, 50 percent. Formation chance through 5 days, medium, 50 percent.

This storm could become Tropical Storm Irma. Earlier today, it was  a 70 percent chance of forming. It is now 50 percent.

2. A tropical wave located over the far eastern Atlantic Ocean, almost a thousand miles west of the Cabo Verde Islands, is producing limited shower and thunderstorm activity. Environmental conditions appear somewhat conducive for gradual development over the next few days while the system moves west-northwestward to northwestward at about 20 mph, but upper-level winds are forecast to become unfavorable by the middle of next week.
Formation chance through 48 hours, low, 10 percent. Formation chance through 5 days, low, 30 percent.

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