Tropical Storm Ida

Tropical Depression Ida Track 1600 Hours August 30 2021
Tropical Depression Ida Track 1600 Hours August 30 2021
Tropical Storm Ida Flash Flood Risk
Ida Flash Flood Risk

Tropical Storm IdaNWS National Hurricane Center Miami FL 400 PM CDT Mon Aug 30, 2021 (see 4:00 video below)

Ida has continued to weaken while moving farther inland over west-central Mississippi this afternoon. Recent observations indicate that the stronger winds seen this morning along the northern Gulf coast have now dropped below tropical storm strength, and Ida has become a tropical depression. Additional weakening should occur while Ida moves over northeastern Mississippi and the Tennessee Valley during the next 12 to 24 hours. Ida is forecast to become an extratropical cyclone over the eastern United States by late Wednesday, and it is likely to be absorbed within a frontal boundary over the western Atlantic by the end of the forecast period.

Ida has turned northeastward and is now moving 020/8 kt. A mid- to upper-level trough approaching Ida from the west should cause the cyclone to move faster toward the northeast over the next couple of days. The latest runs of the dynamical models are in a bit better agreement regarding the forward speed of the Ida as it moves across the eastern U.S., and the NHC track forecast is again near the middle of the guidance envelope.

Although Ida’s winds have decreased, the threat of heavy rainfall and flooding will continue to spread inland over portions of the Tennessee and Ohio Valleys, the Central and Southern Appalachians and the Mid-Atlantic through Wednesday.

This is the last advisory issued by the National Hurricane Center on Ida. 

Key Messages:

  • 1. Ida will continue to produce heavy rainfall tonight through Tuesday morning across portions of southeast Louisiana, Mississippi, and western Alabama, resulting in considerable flash and urban flooding and significant river flooding impacts. Rivers in the Lower Mississippi Valley will remain elevated into next week. As Ida moves inland, additional considerable flooding impacts are likely across portions of the Tennessee Valley, the Ohio Valley, and particularly in the Central and Southern Appalachians into the Mid-Atlantic through Wednesday.
  • 2. In areas that experienced damage and power loss, individuals should use extreme caution during the recovery phase. Post-storm fatalities and injuries often result from heart attacks, heat exhaustion, accidents related to clean up and recovery, and carbon monoxide poisoning from improper generator use.
FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 32.6N  90.3W   30 KT  35 MPH - Depression (ENE Kearney Park,MS)
 12H  31/0600Z 33.6N  89.3W   25 KT  30 MPH - Depression (WSW Walthall,MS)
 24H  31/1800Z 34.8N  87.2W   25 KT  30 MPH - Depression (ESE Rogersville,AL)
 36H  01/0600Z 36.3N  84.3W   20 KT  25 MPH - Depression (WNW Caryville,TN)
 48H  01/1800Z 38.0N  80.7W   20 KT  25 MPH - Post Tropical (ENE Hines,WV)
 60H  02/0600Z 39.0N  77.0W   25 KT  30 MPH - Post Tropical (ENE Silver Spring,MD)
 72H  02/1800Z 39.5N  74.2W   30 KT  35 MPH - Post Tropical (ESE Beach Haven,NJ)
 96H  03/1800Z 41.0N  67.9W   30 KT  35 MPH - Post Tropical (ESE Nantucket,MA)
120H  04/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Mon Aug 30, 2021 

The center of Ida has moved farther inland over western Mississippi this morning and NWS Doppler radar velocities and surface observations indicate that the tropical cyclone’s winds have continued to decrease. The strongest winds are located in a band well southeast of the center along the coasts of Mississippi and Alabama where recent surface reports indicate 30-35 kt winds are still occurring. Therefore, the initial intensity is set at 35 kt. As Ida’s circulation moves farther inland, additional weakening is expected and Ida is expected to become a tropical depression this afternoon. Continued weakening should occur while Ida moves over the Tennessee Valley on Tuesday, and the system is forecast to become extratropical over the eastern United States by late Wednesday. The global models indicate that the post-tropical cyclone will be absorbed by a frontal zone over the western Atlantic by the end of the forecast period.

Ida is moving moving just east of due north or 010/8 kt. A north-northeastward turn should occur later today, followed by a faster northeastward motion tonight and Tuesday as a mid- to upper-level trough approaches the cyclone from the west. The dynamical model guidance remains tightly clustered with very little cross-track spread, although there remains some speed or along-track spread in the guidance. The NHC forecast is near the HCCA and TCVA consensus models.

Key Messages:

  • 1. Dangerous storm surge inundation will continue into this afternoon along portions of the coasts of Mississippi and Alabama.
  • 2. Tropical storm force winds, especially in gusts, will continue over portions of southeastern Louisiana, southern Mississippi and southern Alabama this afternoon.
  • 3. Ida will continue to produce heavy rainfall tonight through Tuesday morning across portions of southeast Louisiana, Mississippi, and western Alabama, resulting in considerable flash and urban flooding and significant river flooding impacts. Rivers in the Lower Mississippi Valley will remain elevated into next week. As Ida moves inland, additional considerable flooding impacts are likely across portions of the Tennessee Valley, the Ohio Valley, and particularly in the Central and Southern Appalachians into the Mid-Atlantic through Wednesday.
  • 4. In areas that experienced damage and power loss, individuals should use extreme caution during the recovery phase. Post-storm fatalities and injuries often result from heart attacks, heat exhaustion, accidents related to clean up and recovery, and carbon monoxide poisoning from improper generator use.
FORECAST POSITIONS AND MAX WINDS

INIT  30/1500Z 31.9N  90.7W   35 KT  40 MPH - Tropical Storm (WSW Willing,MS)
 12H  31/0000Z 33.1N  90.1W   30 KT  35 MPH - Depression (WSW Lexington,MS)
 24H  31/1200Z 34.5N  88.4W   25 KT  30 MPH - Depression (ESE Marietta,MS)
 36H  01/0000Z 35.8N  85.9W   20 KT  25 MPH - Depression (ENE Centertown,TN)
 48H  01/1200Z 37.5N  82.5W   20 KT  25 MPH - Post Tropical (ENE Pikeville,KY)
 60H  02/0000Z 38.9N  78.7W   20 KT  25 MPH - Post Tropical (WSW Rockland,WV)
 72H  02/1200Z 39.5N  75.7W   25 KT  30 MPH - Post Tropical (WSW Mount Pleasant,DE)
 96H  03/1200Z 40.5N  70.5W   30 KT  35 MPH - Post Tropical (ESE Montauk,NY)
120H  04/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 AM CDT Mon Aug 30, 2021 

Ida is now located well inland over southwestern Mississippi and weakening rapidly. However, Doppler velocity data from the Slidell, Louisiana, WSR-88D radar before it went down was still indicating velocity values near 90 kt between 4,000-4,500 ft, while the latest velocity data from Jackson, Mississippi, have been in the 70-75 kt range between 7,500 and 8,000 ft well east of the center. Thus, Ida will still be capable of producing damaging wind gusts in some of the stronger showers and thunderstorms for the next few hours. The intensity at 0600 UTC was 65 kt, which was based on a decay rate of about 10 kt per hour. A slightly slower decay rate of about 5 kt per hour has been used since then, which is the basis for the 50-kt advisory intensity at 0900 UTC. The estimated pressure of 990 mb is based on surface observation data, especially from McComb, Mississippi (KMCB), which has been reporting pressures near 995 mb with 25-30 kt of wind the past couple of hours.

The initial motion estimate is now 355/07 kt. Ida should continue moving northward today around the western periphery of a deep-layer ridge situated over the southeastern United States. A faster motion toward the northeast is expected by Tuesday as a mid- to upper-level trough approaches the cyclone, with that motion continuing through the remainder of the week. The new NHC track forecast is just a tad to the south of the previous advisory, and lies down the middle off the tightly packed consensus models.

Rapid weakening will continue as Ida moves farther inland over Mississippi due to land interaction and southwesterly vertical wind shear of more than 20 kt. However, damaging winds, especially in gusts, are expected to continue over southeastern Louisiana and southwestern Mississippi through through this morning. To account for this, the gust factor in the Forecast/Advisory has been adjusted accordingly. Ida is likely to weaken to a tropical depression this evening. Some slight restrengthening as an extratropical storm is possible when Ida moves over the western Atlantic in the day 4-5 period. In addition, heavy rains will spread northward and then northeastward along the forecast track.

Key Messages:

  • 1. Dangerous storm surge inundation will continue through this morning along portions of the coast between Grand Isle, Louisiana, to Bay St. Louis, Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher.
  • 2. Damaging winds, especially in gusts, will continue to spread inland near the track of Ida’s center into southwestern Mississippi through this morning and early afternoon. These winds will likely lead to widespread tree damage and power outages.
  • 3. Ida will continue to produce heavy rainfall tonight through Tuesday morning across portions of southeast Louisiana, coastal Mississippi, and southwestern Alabama resulting in considerable to life-threatening flash and urban flooding and significant riverine flooding impacts. As Ida moves inland, considerable flooding impacts are possible across portions of the Lower Mississippi Valley, Tennessee Valley, Ohio Valley, Central and Southern Appalachians, and Mid-Atlantic through Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 31.0N  90.8W   50 KT  60 MPH - Tropical Storm (WSW Gillsburg,MS)
 12H  30/1800Z 32.2N  90.6W   30 KT  35 MPH - Depression (WNW Learned,MS)
 24H  31/0600Z 33.7N  89.4W   25 KT  30 MPH - Depression (WSW Slate Springs, MS)
 36H  31/1800Z 35.1N  87.2W   25 KT  30 MPH - Depression (WNW Minor Hill,TN)
 48H  01/0600Z 36.6N  84.3W   20 KT  25 MPH - Post Tropical (ESE Pine Knot,KY)
 60H  01/1800Z 38.1N  80.8W   20 KT  25 MPH - Post Tropical (ENE Nutterville,WV)
 72H  02/0600Z 39.0N  77.4W   25 KT  30 MPH - Post Tropical (ESE Sterling,VA)
 96H  03/0600Z 40.1N  71.5W   30 KT  35 MPH - Post Tropical (ESE Montauk,NY)
120H  04/0600Z 40.5N  67.2W   30 KT  35 MPH - Post Tropical (WSW Nantucket,MA)

NWS National Hurricane Center Miami FL 1000 PM CDT Sun Aug 29, 2021

Although Ida has been inland over southeastern Louisiana for several hours, it is still a very well organized hurricane. Doppler radar images indicate that the hurricane continues to have a well-defined eye, though the eyewall has become a bit ragged on the southwest side. Beyond the inner core, rain bands remain well established, especially on the system’s east side. Earlier this evening, there were reports of extreme wind gusts over 120 kt along the coast of southeastern Louisiana. Based on Doppler radar velocity data over the past hour or two, the initial intensity is estimated to be 90 kt.

As Ida continues inland, rapid weakening is expected due to a combination of land interaction and an increase in wind shear. However, damaging winds, especially in gusts, are expected to spread further inland over southeastern Louisiana and southwestern Mississippi through Monday morning. To account for this, the gust factor in the Forecast/Advisory has been adjusted accordingly. Ida is likely to weaken to a tropical storm by Monday morning and a tropical depression by Monday night. Some slight restrengthening as an extratropical storm is possible when Ida moves over the western Atlantic in 4 days or so. In addition, heavy rains will spread northward and then northeastward along the forecast track.

Ida is expected to turn northward by early Monday as it moves in the flow on the western side of a subtropical ridge. A faster motion to the northeast is expected by Tuesday as a mid- to upper-level trough approaches the system, with that motion continuing through much of the remainder of the week. The NHC track forecast is a little to the south or right of the previous one to come into better agreement with the latest models.

Key Messages:

  • 1. Life-threatening storm surge inundation will continue through tonight along portions of the coast between Burns Point, Louisiana, to Ocean Springs, Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher.
  • 2. Wind damage will occur near the core of Ida as it continues inland over southeastern Louisiana during the next few hours. Damaging winds, especially in gusts, will spread inland near the track of Ida’s center into southwestern Mississippi through early Monday. These winds will likely lead to widespread tree damage and power outages.
  • 3. Ida will continue to produce heavy rainfall tonight through Monday across southeast Louisiana, coastal Mississippi, and southwestern Alabama, resulting in considerable to life-threatening flash and urban flooding and significant riverine flooding impacts. As Ida moves farther inland, considerable flooding impacts are possible across portions of the Lower Mississippi Valley, Tennessee Valley, Upper Ohio Valley, Central Appalachians, and Mid-Atlantic through Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  30/0300Z 30.3N  90.7W   90 KT 105 MPH - Category 2 (WNW Whitehall, LA)
 12H  30/1200Z 31.5N  90.8W   50 KT  60 MPH - Tropical Storm (WSW Eddiceton, MS)
 24H  31/0000Z 33.0N  90.1W   30 KT  35 MPH - Depression (WNW Ebenezer, MS)
 36H  31/1200Z 34.6N  88.5W   25 KT  30 MPH - Depression (ESE Booneville, MS)
 48H  01/0000Z 36.1N  85.9W   25 KT  30 MPH - Post Tropical (WSW Lancaster, TN)
 60H  01/1200Z 37.5N  82.5W   25 KT  30 MPH - Post Tropical (ENE Pikeville, KY)
 72H  02/0000Z 38.9N  78.8W   30 KT  35 MPH - Post Tropical (ESE Lost City, WV)
 96H  03/0000Z 40.0N  72.5W   35 KT  40 MPH - Post Tropical (ESE New York City,NY)
120H  04/0000Z 40.7N  67.9W   35 KT  40 MPH - Post Tropical (ESE Nantucket,MA)

NWS National Hurricane Center Miami FL 400 PM CDT Sun Aug 29, 2021 

NWS Doppler radar imagery and data from an Air Force Reserve Reserve Hurricane Hunter aircraft showed that Ida made landfall around 1655 UTC along the southeastern coast of Louisiana near Port Fourchon with estimated maximum winds of 130 kt and a minimum pressure around 930 mb. Since that time, Ida made a second landfall southwest of Galliano, Louisiana, and with the eyewall now onshore weakening has begun. Based on the latest Doppler velocities the initial wind speed has been conservatively reduced to 115 kt for this advisory. As Ida’s circulation moves farther inland this evening and overnight a faster rate of weakening is expected, and Ida is forecast to become a tropical depression over Mississippi by late Monday. Although weakening is forecast, damaging winds, especially in gusts, are expected to spread inland over southeastern Louisiana and southwestern Mississippi through Monday morning. To account for this, the gust factor in the Forecast/Advisory has been adjusted accordingly. By 72 hours, Ida is predicted to merge with a frontal zone over the eastern United States and become an extratropical low, and this low is forecast to strengthen into a gale center near Atlantic Canada by the end of the forecast period.

Radar fixes indicate that Ida’s forward motion has slowed and the initial motion estimate is 325/9 kt. The hurricane should turn northward tonight around the western periphery of a deep-layer ridge near the southeastern United States coast. Ida is forecast to turn northeastward and recurve over the eastern United States as it enters the mid-latitude westerlies. The GFS is a bit faster in ejecting the post-tropical cyclone northeastward on days 3 through 5, and the NHC forecast follows a blend of the various consensus models and the GFS ensemble mean.

Key Messages:

  • 1. Extremely life-threatening storm surge inundation of 9 feet or greater above ground level will continue through early this evening along portions of the coast between Burns Point, Louisiana, to Ocean Springs, Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher.
  • 2. Catastrophic wind damage will occur near the core of Ida as it moves inland over southeastern Louisiana during the next few hours. Hurricane-force winds and damaging wind gusts are expected through tonight within the Hurricane Warning area in southeastern Louisiana, including metropolitan New Orleans.
  • 3. Damaging winds, especially in gusts, will spread inland near the track of the center of Ida into southwestern Mississippi tonight and early Monday. These winds will likely lead to widespread tree damage and power outages.
  • 4. Ida will continue to produce heavy rainfall through Monday across the central Gulf Coast across southeast Louisiana, coastal Mississippi, and southwestern Alabama, resulting in considerable to life-threatening flash and urban flooding and significant river flooding impacts. As Ida moves inland, significant flooding impacts are possible across portions of the Lower Mississippi Valley, Tennessee Valley, Upper Ohio Valley, Central Appalachians, and Mid-Atlantic through Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 29.5N  90.6W  115 KT 130 MPH - Category 4 (WNW Chauvin,LA)
 12H  30/0600Z 30.7N  90.9W   65 KT  75 MPH - Category 1 (WNW Baywood,LA)
 24H  30/1800Z 32.4N  90.7W   35 KT  40 MPH - Tropical Storm (ENE Vicksburg, MS)
 36H  31/0600Z 34.0N  89.4W   25 KT  30 MPH - Depression (ESE Ellard, MS)
 48H  31/1800Z 35.6N  87.2W   25 KT  30 MPH - Depression (WSW Columbia,TN)
 60H  01/0600Z 37.1N  84.2W   20 KT  25 MPH - Post Tropical (ENE Buch,KY)
 72H  01/1800Z 38.6N  80.5W   20 KT  25 MPH - Post Tropical (WNW Big Run,WV)
 96H  02/1800Z 41.3N  72.5W   30 KT  35 MPH - Post Tropical (ENE Clinton,CT)
120H  03/1800Z 43.8N  67.0W   35 KT  40 MPH - Post Tropical (WSW Yarmouth,NS Canada)

NWS National Hurricane Center Miami FL 1000 AM CDT Sun Aug 29, 2021 

Ida’s rapid strengthening appears to have leveled off within the past hour or so. NOAA and Air Force Reserve Hurricane Hunter aircraft that have been in the storm this morning have reported peak flight-level winds of 146 to 148 kt between 8000 and 10000 ft, and believable SFMR winds around 130 kt. Based on these observations, the initial wind speed remains 130 kt for this advisory. The central pressure appears to have bottomed out around 929 mb, and the latest dropsonde in the eye from the Air Force plane supports a minimum pressure of 933 mb. Ida’s satellite and radar presentation is very impressive, as the 15-nm-wide eye is very well-defined and surrounded by a ring of intense convection. Within the past hour or so, there is evidence in radar imagery of a secondary eyewall, and this has likely caused Ida’s intensity to level off for now. Although Ida’s extreme winds are confined to the inner eyewall, the aircraft data indicate that hurricane-force winds extend outward about 45 n mi to the northeast of the center, and based on buoy data the tropical-storm-force wind field extends outward about 130 n mi northeast of the center.

Ida’s eyewall is nearing the coast of Louisiana, and any additional strengthening seems less likely now given the recent structural changes of the inner core. While rapid weakening should occur after landfall, damaging winds will penetrate well inland across southeastern Louisiana and southwestern Mississippi through tonight. Ida is forecast to weaken to a tropical depression over Mississippi by late Tuesday. The global model guidance now indicates that Ida will likely transition to an extratropical low when it nears the east coast of the United States and the new forecast shows the extratropical low becoming a gale center near Atlantic Canada at day 5.

Ida has begun to slow down according to the latest aircraft and radar fixes, and the initial motion estimate is 320/11 kt. Ida’s forward speed is likely to slow further during the next 12 to 24 hours as the hurricane turns north-northwestward, and then northward around the western periphery of a deep-layer ridge near the southeastern United States coast. The cyclone is predicted to turn northeastward by late Tuesday ahead of a short-wave trough that will move across the central United States. The new NHC track is close to the HCCA corrected consensus and the GFS ensemble mean, and is not very different from the previous advisory.

Key Messages:

  • 1. Extremely life-threatening storm surge inundation of 9 feet or greater above ground level is imminent somewhere within the area from Burns Point, Louisiana, to Ocean Springs, Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher.
  • 2. Catastrophic wind damage will occur where the core of Ida moves onshore along the southeast coast of Louisiana in the next few hours. Hurricane-force winds and damaging wind gusts are expected today within the Hurricane Warning in southeastern Louisiana, including metropolitan New Orleans.
  • 3. Damaging winds, especially in gusts, will spread inland near the track of the center of Ida into southwestern Mississippi tonight and early Monday. These winds will likely lead to widespread tree damage and power outages.
  • 4. Ida will continue to produce heavy rainfall today through Monday across the central Gulf Coast from southeast Louisiana, coastal Mississippi, and far southwestern Alabama, resulting in considerable to life-threatening flash and urban flooding and significant river flooding impacts. As Ida moves inland, significant flooding impacts are possible across portions of the Lower Mississippi, Tennessee Valley, Upper Ohio Valley, Central Appalachians and the Mid-Atlantic through Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  29/1500Z 28.8N  90.0W  130 KT 150 MPH - Category 4 (ESE Port Fourchon,LA)
 12H  30/0000Z 30.0N  90.8W   90 KT 105 MPH - Category 2 (WSW Hester,LA)
 24H  30/1200Z 31.6N  91.0W   50 KT  60 MPH - Tropical Storm (WNW Oldenburg,MS)
 36H  31/0000Z 33.2N  90.3W   30 KT  35 MPH - Depression (WNW Tchula,MS)
 48H  31/1200Z 34.9N  88.5W   25 KT  30 MPH - Depression (ESE Corinth,MS)
 60H  01/0000Z 36.4N  85.9W   20 KT  25 MPH - Depression (ENE Pleasant Shade,TN)
 72H  01/1200Z 37.8N  82.5W   20 KT  25 MPH - Post Tropical (WSW Beauty,KY)
 96H  02/1200Z 40.5N  74.2W   30 KT  35 MPH - Post Tropical (WSW Pleasant Plains,NY)
120H  03/1200Z 43.5N  67.0W   35 KT  40 MPH - Post Tropical (WSW Yarmouth,NS Canada)

NWS National Hurricane Center Miami FL 1000 PM CDT Sat Aug 28, 2021

The NOAA Hurricane Hunters investigated Ida earlier this evening and found that the maximum winds were still around 90 kt. Although the peak winds appear to have leveled off for now, the minimum pressure has continued to fall and was down to 966 mb at the last pass through the center an hour or two ago. In fact, the pressure has been dropping by about 2 mb per hour based on the aircraft data. In addition, tail Doppler Radar data from the aircraft indicate that the vortex has become more symmetric and that the inner core has contracted from the mission earlier today. These are signals that Ida is poised to strengthen further, and based on recent satellite images it appears that strengthening is imminent. Flight-level and SFMR observations also indicate that Ida’s wind field has expanded and there is some indication of a double-wind maximum. The tropical-storm-force winds now extend outward up to 120 n mi from the center and hurricane-force winds up to 35 n mi from the eye.

Ida continues to move steadily to the northwest at about 14 kt. There has been little change to the track forecast rationale. A subtropical ridge situated near the southeast U.S. coast is expected to shift westward during the next day or two. This feature should continue to steer Ida northwestward toward the Louisiana coast. The latest runs of the numerical models bring the center of Ida to southeast or south-central Louisiana Sunday afternoon. Although landfall is not expected for about 18 hours, impacts will begin well before that time. Tropical-storm-force winds are likely to begin overnight, therefore, all preparations to protect life and property must be rushed to completion. The new track forecast is just a little to the east of the previous one through landfall. After Ida moves inland, a turn to the north and then the northeast is expected as the storm moves in the flow on the northwest and north sides of the ridge.

Ida remains over waters with high oceanic heat content, and in an atmospheric environment of low wind shear and abundant moisture. These conditions, combined with the improved structure of the hurricane, should allow Ida to rapidly intensify until it makes landfall. The models remain in fairly good agreement, and the NHC forecast holds steady and brings Ida to a dangerous major hurricane prior to landfall. After the storm moves inland on Sunday, rapid weakening is forecast due to a combination of land interaction, drier air and some increase in wind shear.

Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center. Rainfall impacts will also spread inland across the Lower Mississippi and Tennessee Valleys through early next week.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana, Mississippi, and Alabama within the Storm Surge Warning area. Extremely life-threatening inundation of 9 feet or greater above ground level is possible somewhere within the area from Morgan City, Louisiana, to the coast of Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher. Interests throughout the warning area should follow any advice given by local officials.
  • 2. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
  • 3. Damaging winds, especially in gusts, will spread inland near the track of the center of Ida across portions of southeastern Louisiana and southwestern Mississippi Sunday night and early Monday. These winds will likely lead to widespread tree damage and power outages.
  • 4. Ida is likely to produce heavy rainfall Sunday into Monday across the central Gulf Coast from southeast Louisiana, coastal Mississippi, and far southwestern Alabama, resulting in considerable to life-threatening flash and urban flooding and significant river flooding impacts. As Ida moves inland, significant flooding impacts are possible across portions of the Lower Mississippi, Tennessee, and Ohio Valleys through Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 27.2N  88.0W   90 KT 105 MPH - Category 2 (WSW Sarasota,FL)
 12H  29/1200Z 28.4N  89.4W  115 KT 130 MPH - Category 3 (ESE Grand Isle,LA)
 24H  30/0000Z 29.9N  90.7W   85 KT 100 MPH - Category 2 (WNW Choctaw,LA)
 36H  30/1200Z 31.4N  91.2W   45 KT  50 MPH - Tropical Storm (WNW Knoxville,MS)
 48H  31/0000Z 33.1N  90.6W   30 KT  35 MPH - Depression (WNW  Midnight,MS)
 60H  31/1200Z 34.8N  89.1W   25 KT  30 MPH - Depression (ESE Ashland,MS)
 72H  01/0000Z 36.3N  86.7W   20 KT  25 MPH - Depression (ESE Nashville,TN)
 96H  02/0000Z 38.6N  80.6W   20 KT  25 MPH - Post Tropical (WSW Centralia,WV)
120H  03/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sat Aug 28, 2021 

Ida’s satellite presentation has continued to improve this afternoon, with the eye becoming more apparent in both infrared and visible satellite imagery. The eye is surrounded by a symmetric ring of cold cloud tops and new convection with lightning as seen by the GOES-16 GLM sensor has been rotating around the western portion of the eyewall within the past few hours. The upper-level outflow has also become well established over the hurricane and several spiral bands are noted over the northern semicircle. Subjective Dvorak satellite intensity estimates have increased to T5.0 and these support increasing the initial intensity to 90 kt for this advisory. Both NOAA and Air Force Reserve reconnaissance aircraft are scheduled to be in the hurricane within the next few hours and should provide additional information on Ida’s current strength. Earlier aircraft and satellite wind data indicate that the tropical-storm-force wind field has continued to expand over the eastern semicircle and the initial wind radii have been adjusted outward.

The hurricane appears to have begun its anticipated rapid intensification phase. A favorable upper-level wind pattern, warm waters along the track, and a moist atmosphere are expected to allow for additional rapid strengthening overnight and early Sunday. This is again supported by the majority of the intensity models, and the NHC wind speed forecast continues to call for rapid strengthening, bringing Ida to Category 4 status within 12 to 18 hours. An eyewall replacement cycle could occur as Ida nears the northern Gulf coast, so some fluctuations in intensity are possible during that time. After landfall, rapid weakening is expected, and Ida is forecast to become a post-tropical cyclone by day 4, and it is likely to be absorbed along a frontal zone by day 5.

Ida has moved a little to the right of the previous track, but the long-term motion motion is still northwestward or 320/14 kt. The track forecast philosophy remains unchanged. Ida is expected to continue on a northwestward heading through late Sunday as it is steered around the southwestern portion of a deep-layer ridge near the southeastern United Stated coast. After landfall, Ida’s forward motion is forecast to slow when it turns northward around the western extent of the aforementioned ridge. By Tuesday, the cyclone should reach the southern extent of the mid-latitude westerlies, causing it to turn north-northeastward across the Lower Mississippi and Tennessee Valleys. The track guidance has nudged slightly eastward during the first 12-24 hours, primarily due to the more northeastward initial position, and this has required a slight rightward adjustment in the new official forecast at those times. The remainder of the NHC forecast is largely unchanged from before, and lies near various consensus models and the GFS ensemble mean.

Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center. Rainfall impacts will also spread inland across the Lower Mississippi and Tennessee Valleys through early next week after Ida makes landfall.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana, Mississippi, and Alabama within the Storm Surge Warning area. Extremely life-threatening inundation of 9 feet or greater above ground level is possible somewhere within the area from Morgan City, Louisiana, to the coast of Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher. Interests throughout the warning area should follow any advice given by local officials.
  • 2. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
  • 3. Damaging winds, especially in gusts, will spread inland near the track of the center of Ida across portions of southeastern Louisiana and southwestern Mississippi Sunday night and early Monday. These winds will likely lead to widespread tree damage and power outages.
  • 4. Ida is likely to produce heavy rainfall Sunday into Monday across the central Gulf Coast from southeast Louisiana, coastal Mississippi, and far southwestern Alabama, resulting in considerable to life-threatening flash and urban flooding and significant river flooding impacts. As Ida moves inland, significant flooding impacts are possible across portions of the Lower Mississippi, Tennessee, and Ohio Valleys through Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 26.2N  87.0W   90 KT 105 MPH - Category 2 (WSW Fort Myers,FL)
 12H  29/0600Z 27.5N  88.6W  110 KT 125 MPH - Category 3 (ESE New Orleans, LA)
 24H  29/1800Z 29.1N  90.4W  115 KT 130 MPH - Category 4 (ENE Timbailer Island,LA)
 36H  30/0600Z 30.5N  91.3W   65 KT  75 MPH - Category 1 (WNW Lobdell Station,LA)
 48H  30/1800Z 32.2N  91.2W   35 KT  40 MPH - Tropical Storm (ESE Quimby,LA)
 60H  31/0600Z 34.0N  90.1W   25 KT  30 MPH - Depression (WSW Charleston,MS)
 72H  31/1800Z 35.7N  88.1W   20 KT  25 MPH - Depression (ENE Parsons,TN)
 96H  01/1800Z 38.0N  82.5W   20 KT  25 MPH - Post Tropical (ESE Glenhayes,WV)
120H  02/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sat Aug 28, 2021 

The satellite presentation of Ida has continued to improve this morning with the center embedded within a fairly symmetric Central Dense Overcast and hints of the eye in both visible in infrared satellite imagery. Earlier microwave imagery revealed a well- defined low- to mid-level eye and excellent spiral banding over the northern semicircle. Both NOAA and Air Force Reserve hurricane hunter aircraft, somewhat surprisingly, have not found a significantly deepening tropical cyclone yet, but given the very recent increase in organization and structure, the winds are likely to catch up to the satellite appearance very soon. Using the latest flight-level and SFMR wind data from the aircraft and satellite intensity estimates the initial wind speed remains 75 kt for this advisory. The aircraft data does indicate that Ida’s wind field has expanded, and the NHC wind radii have been adjusted accordingly.

Given the improved inner-core structure Ida appears poised to rapidly intensify during the next 12 to 24 hours as it remains within a favorable environment of low vertical wind shear and over warm water. Although the interpolated intensity guidance has lowered somewhat due to the fact that Ida has not significantly strengthened yet, the explicit forecasts from the dynamical models continue to support significant deepening, and the latest runs of the HWRF and HMON models indicate Ida will reach Category 4 strength before landfall. The new NHC intensity forecast calls for rapid intensification to Category 4 strength during the next 24 hours. After that time, fluctuations in intensity are possible due to eyewall replacement cycles as Ida approaches the northern Gulf coast. After landfall, rapid weakening is expected and Ida is forecast to weaken to a tropical depression by Monday night, and become a post-tropical cyclone as it moves over the Tennessee Valley by mid-week.

Ida has been moving steadily northwestward or 315/14 kt. A deep layer ridge near the southeastern United States coast is forecast to shift westward during the next day or so, and this should continue to steer Ida northwestward through landfall on Sunday. The track guidance remains in remarkably good agreement through 36 hours, and the new NHC track forecast is essentially unchanged during that time, and continues to indicate that Ida will reach the coast of Louisiana on Sunday. After landfall, Ida will be near the western extent of the ridge and should turn northward and then northeastward as it recurves into the southern portion of the mid-latitude westerlies. The track guidance has shifted slightly westward beyond 48 hours, and the track forecast over the southern U.S. and the Tennessee Valley has been adjusted accordingly. Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center. Wind and rainfall impacts will also penetrate inland through early next week after Ida makes landfall.

Key Messages:

  • 1. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana and Mississippi within the Storm Surge Warning area. Extremely life-threatening inundation of 9 feet or greater above ground level is possible somewhere within the area from Morgan City, Louisiana, to the coast of Mississippi. Overtopping of local levees outside of the Hurricane and Storm Damage Risk Reduction System is possible where local inundation values may be higher. Interests throughout the warning area should follow any advice given by local officials.
  • 2. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion today in the warning area.
  • 3. Ida is likely to produce heavy rainfall Sunday and Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi, resulting in life-threatening flash and urban flooding and significant river flooding impacts. As Ida moves inland, significant flooding impacts are likely across portions of the Lower Mississippi and Tennessee Valleys Monday and Tuesday.
FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 24.8N  86.1W   75 KT  85 MPH - Category 1 (WSW Key West,FL)
 12H  29/0000Z 26.3N  87.9W  100 KT 115 MPH - Category 3 (WSW Fort Myers,FL)
 24H  29/1200Z 28.0N  89.8W  115 KT 130 MPH - Category 4 (ESE Grand Isle,LA)
 36H  30/0000Z 29.4N  91.0W  115 KT 130 MPH - Category 4 (WNW Dulac,LA)
 48H  30/1200Z 31.0N  91.5W   60 KT  70 MPH - Tropical Storm (WSW Pinckneyville,MS)
 60H  31/0000Z 32.7N  91.0W   30 KT  35 MPH - Depression (ESE Fitler,MS)
 72H  31/1200Z 34.4N  89.8W   25 KT  30 MPH - Depression (ESE Sardis,MS)
 96H  01/1200Z 36.8N  85.3W   20 KT  25 MPH - Post Tropical (ENE Burkesville,KY)
120H  02/1200Z 37.9N  79.9W   20 KT  25 MPH - Post Tropical (ESE Valley View,VA)

NWS National Hurricane Center Miami FL 400 AM CDT Sat Aug 28, 2021

Just after the last advisory, the convective structure of Ida got a bit ragged, probably due to the residual effects of land interaction with Cuba and a tongue of dry air that wrapped into the eastern side of the circulation. However, latest radar images from Cuba show that the eye is becoming better defined, and satellite imagery shows cooling of the cloud tops in the eyewall. The initial intensity has been held at 70 kt based on the latest trends and earlier Hurricane Hunter aircraft data. NOAA and Air Force reserve Hurricane Hunter aircraft are scheduled to investigate Ida again starting around 12Z.

The initial motion remains northwestward or 315/14. A subtropical ridge centered off the southeast U.S. coast is expected to shift westward through the weekend, and this feature should continue to provide a steering flow that will take Ida steadily northwestward across the Gulf of Mexico during the next 36-48 h. The track guidance remains in good agreement that Ida will make landfall on the coast of southeastern or central Louisiana late Sunday or early Monday morning. After landfall, Ida is expected to turn northward through Louisiana and western Mississippi at a slower forward speed as it moves around the western end of the ridge. Recurvature into the westerlies and an east-northeastward motion are expected by the end of the forecast period. The new forecast track is nudged slightly to the west after 36 h to keep it near the various consensus models, but this is not a significant change from the previous forecast. Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center.

Ida is expected to remain in a favorable environment of light vertical shear and very warm sea-surface temperatures until it makes landfall. The only negative factor is the possibility that dry air may try to entrain into the system and slow the expected intensification. The SHIPS and LGEM models are showing a little less strengthening than previously. However, the HWRF and HMON models continue to forecast Ida to reach Category 4 intensity before landfall. The new intensity forecast will forecast a peak intensity of 120 kt in best agreement with the HWRF and HMON, and the pre-landfall part of the forecast is little changed from the previous forecast. After landfall, rapid weakening is expected due to land interaction, drier air, and an increase in shear, and Ida is expected to become a post-tropical cyclone as it moves through the Tennessee Valley.

As Ida continues to intensify over the Gulf of Mexico, an expansion of its wind field is predicted. The NHC wind radii forecast is largely based on the radii consensus, and winds of at least tropical storm force are likely to reach the coast Sunday morning. Therefore, all preparations to protect life and property for this dangerous event need to be made today.

Key Messages:

  • 1. Hurricane and tropical storm conditions are ending over Cuba. However, Ida will continue to bring periods of heavy rain across western Cuba through today that may lead to flash flooding and mudslides.
  • 2. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana and Mississippi within the Storm Surge Warning area. Extremely life-threatening inundation of 10 to 15 feet above ground level is possible within the area from Morgan City, Louisiana, to the Mouth of the Mississippi River. Interests throughout the warning area should follow any advice given by local officials.
  • 3. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
  • 4. Ida is likely to produce heavy rainfall later Sunday into Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi resulting in significant flash and riverine flooding impacts. As Ida moves inland, flooding impacts are possible across portions of the Lower Mississippi and Tennessee Valleys.
FORECAST POSITIONS AND MAX WINDS

INIT  28/0900Z 24.0N  85.2W   70 KT  80 MPH - Category 1 (WSW Key West,FL)
 12H  28/1800Z 25.4N  86.9W   85 KT 100 MPH - Category 2 (WSW Naples,FL)
 24H  29/0600Z 27.1N  88.9W  105 KT 120 MPH - Category 3 (WSW New Orleans,LA)
 36H  29/1800Z 28.6N  90.5W  120 KT 140 MPH - Category 4 (WSW Grand Isle,LA)
 48H  30/0600Z 30.1N  91.3W   85 KT 100 MPH - Category 2 (WSW Augusta,LA)
 60H  30/1800Z 31.6N  91.2W   45 KT  50 MPH - Tropical Storm (ESE Cannonsburg,MS)
 72H  31/0600Z 33.2N  90.5W   30 KT  35 MPH - Depression (WNW Belzoni,MS)
 96H  01/0600Z 36.0N  87.0W   25 KT  30 MPH - Depression (WSW Pasquo,TN)
120H  02/0600Z 37.5N  82.5W   20 KT  25 MPH - Post Tropical (ENE Pikeville,KY)

NWS National Hurricane Center Miami FL 1100 PM EDT Fri Aug 27, 2021

Ida made landfall in the Cuban province of Pinar Del Rio around 2320 UTC with maximum sustained winds estimated to be around 70 kt. Radar data from Cuba indicate that the inner core of Ida has remained intact after its passage over western Cuba with a well-defined eye and relatively symmetric eyewall evident. In addition, satellite images show deep convection increasing in both intensity and coverage, a sign that Ida is strengthening. The Air Force Hurricane Hunters are currently investigating Ida and so far have found maximum 700 mb flight-level winds of 75 kt. Based on that data, the initial intensity is held at 70 kt.

The hurricane is moving northwestward at about 13 kt. A subtropical ridge centered off the southeast U.S. coast is expected to shift westward through the weekend. This feature should continue to provide a steering flow that will take Ida steadily northwestward across the Gulf of Mexico during the next couple of days. The models remain in very good agreement and show Ida making landfall in Louisiana late Sunday or early Monday morning. After the storm moves inland, a decrease in forward speed and a turn to the north and then the northeast is predicted as Ida moves in the flow on the northwest and north sides of the ridge. Since the models are tightly clustered and because the steering flow is well pronounced, there is high confidence in the track forecast. The new NHC track forecast is very similar to the previous one and near the various consensus aids, which are often the most accurate models. Users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center.

Ida is expected to remain in conducive conditions for intensification until it reaches the central Gulf coast. The global models show a very favorable upper-level wind pattern over the storm and abundant environmental moisture. These conducive atmospheric conditions combined with very warm Gulf of Mexico waters should allow Ida to rapidly intensify this weekend. In fact, it seems likely that Ida will pass over a warm eddy over the central Gulf of Mexico, where the ocean heat content is very high. All of the models show significant strengthening, but there is a fair amount of spread on how strong the hurricane will get. The NHC intensity forecast remains near the high end of the model guidance, and shows Ida becoming an extremely dangerous category 4 hurricane prior to reaching the coast. After landfall, rapid weakening is expected due to land interaction, drier air, and an increase in shear.

As Ida continues to intensify over the Gulf of Mexico, an expansion of its wind field is predicted. The NHC wind radii forecast is largely based on the radii consensus, and winds of at least tropical storm force are likely to reach the coast Sunday morning. Therefore, all preparations to protect life and property for this dangerous event need to be made on Saturday.

Key Messages:

  • 1. Life-threatening storm surge and hurricane conditions are expected to continue for the next few hours in portions of western Cuba, including the Isle of Youth, where a Hurricane Warning is in effect. Life-threatening heavy rains, flash flooding and mudslides are expected across Jamaica, the Cayman Islands, and western Cuba, including the Isle of Youth.
  • 2. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana and Mississippi within the Storm Surge Warning area. Extremely life-threatening inundation of 10 to 15 feet above ground level is possible within the area from Morgan City, Louisiana, to the Mouth of the Mississippi River. Interests throughout the warning area should follow any advice given by local officials.
  • 3. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
  • 4. Ida is likely to produce heavy rainfall later Sunday into Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi and Alabama, resulting in considerable flash, urban, small stream, and riverine flooding impacts. As Ida moves inland, flooding impacts are possible across portions of the Lower Mississippi and Tennessee Valleys.
FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 23.0N  84.0W   70 KT  80 MPH - Category 1 (WNW Puerto Esperanza,Cuba)
 12H  28/1200Z 24.4N  85.6W   85 KT 100 MPH - Category 2 (WSW Key West,FL)
 24H  29/0000Z 26.1N  87.7W  105 KT 120 MPH - Category 3 (WNW Naples,FL)
 36H  29/1200Z 27.8N  89.6W  120 KT 140 MPH - Category 4 (ESE New Orleans,LA)
 48H  30/0000Z 29.2N  90.8W  110 KT 125 MPH - Category 3 (WSW Cocodrie,LA)
 60H  30/1200Z 30.7N  91.0W   60 KT  70 MPH - Tropical Storm (ESE Slaughter,LA)
 72H  31/0000Z 32.3N  90.6W   35 KT  40 MPH - Tropical Storm (ESE Edwards, MS)
 96H  01/0000Z 34.9N  88.2W   25 KT  30 MPH - Depression (ESE Short,MS)
120H  02/0000Z 36.8N  83.9W   20 KT  25 MPH - Post Tropical (WSW Artemus,KY)

NWS National Hurricane Center Miami FL 500 PM EDT Fri Aug 27, 2021 

Cuban radar data and reports from an earlier Air Force Reserve Hurricane Hunter mission indicate that Ida’s inner core structure continued to improve after the release of the previous advisory package. An eye became apparent in radar imagery before the center reached the Isle of Youth, and the final fix from the Air Force Hurricane Hunter aircraft reported a closed 24-n-mi wide eye. The aircraft measured winds to support hurricane intensity shortly before 1800 UTC, and during the final northeast eyewall pass, and flight-level wind data support increasing the intensity to 70 kt, which is used as the initial intensity for this advisory.

The upper-level outflow has expanded over all but the southwestern portion of the circulation, and the upper-level wind pattern is forecast to continue to improve overnight and early Saturday. Once Ida moves past western Cuba and into the southeastern Gulf of Mexico, it will be moving through a very favorable oceanic and atmospheric environment consisting of high ocean heat content waters, low vertical wind shear, and a moist low- to mid-level atmosphere. These conditions are likely to result in a period of rapid strengthening during the next 24 to 36 hours. In fact, with the higher initial wind speed, the intensity guidance has significantly increased this cycle, and the bulk of the guidance now brings Ida to category 4 intensity.

The NHC forecast explicitly calls for rapid intensification during the next 24 to 36 hours, which is supported by several of the dynamical models, the LGEM model, and high probabilities of rapid intensification indicated by the SHIPS and DTOPS RI guidance. The NHC forecast is near the IVCN multi-model consensus aid, but is lower than HCCA and LGEM. It should be noted that some fluctuations in intensity are possible as Ida nears the northern Gulf coast due to possible eyewall replacement cycles. In addition to the expected increase in strength, the dynamical model guidance again calls for Ida’s wind field to expand while it moves over the Gulf of Mexico. As a result, there is higher-than-normal confidence that a large and powerful hurricane will impact portions of the northern Gulf coast by late this weekend and early next week.

Ida has wobbled a little right of the previous track, but the longer term motion continues to be northwestward or 320/13 kt. The steering currents remain well-established as a strong deep-layer ridge over the western Atlantic should continue to steer Ida northwestward across the Gulf this weekend. Ida will approach the western portion of the ridge after landfall, and this should result in a slower northward motion by day 3. After that time, a short-wave trough over the central United States is expected to cause the system to turn northeastward. The track guidance remains in remarkably good agreement through landfall along the northern Gulf coast, and there is higher-than-normal confidence in that portion of the track forecast. However, users are again reminded to not focus on the exact details of the track forecast as storm surge, wind, and rainfall impacts will extend far from the center.

Key Messages:

  • 1. Life-threatening storm surge and hurricane conditions are expected to continue through tonight in portions of western Cuba, including the Isle of Youth, where a Hurricane Warning is in effect. Life-threatening heavy rains, flash flooding and mudslides are expected across Jamaica, the Cayman Islands, and western Cuba, including the Isle of Youth.
  • 2. There is a danger of life-threatening storm surge inundation Sunday along the coasts of Louisiana and Mississippi within the Storm Surge Warning area. Extremely life-threatening inundation of 10 to 15 feet above ground level is possible within the area from Morgan City, Louisiana, to the Mouth of the Mississippi River. Interests throughout the warning area should follow any advice given by local officials.
  • 3. Ida is expected to be an extremely dangerous major hurricane when it reaches the coast of Louisiana. Hurricane-force winds are expected Sunday in portions of the Hurricane Warning area along the Louisiana coast, including metropolitan New Orleans, with potentially catastrophic wind damage possible where the core of Ida moves onshore. Actions to protect life and property should be rushed to completion in the warning area.
  • 4. Ida is likely to produce heavy rainfall later Sunday into Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi and Alabama, resulting in considerable flash, urban, small stream, and riverine flooding impacts. As Ida moves inland, flooding impacts are possible across portions of the Lower Mississippi and Tennessee Valleys.
FORECAST POSITIONS AND MAX WINDS

INIT  27/2100Z 22.1N  83.2W   70 KT  80 MPH - Category 1 (ESE La Coloma,Cuba)
 12H  28/0600Z 23.5N  84.8W   85 KT 100 MPH - Category 2 (WNW Mantua,Cuba)
 24H  28/1800Z 25.3N  86.9W  105 KT 120 MPH - Category 3 (WSW Naples,FL)
 36H  29/0600Z 27.1N  89.0W  115 KT 130 MPH - Category 4 (ESE New Orleans,LA)
 48H  29/1800Z 28.6N  90.6W  120 KT 140 MPH - Category 4 (ESE Houma,LA)
 60H  30/0600Z 30.0N  91.3W   80 KT  90 MPH - Category 1 (WNW Pierre Part,LA)
 72H  30/1800Z 31.5N  91.1W   40 KT  45 MPH - Tropical Storm (WSW Roxie,MS)
 96H  31/1800Z 34.4N  89.3W   30 KT  35 MPH - Depression (WNW Thaxton,MS)
120H  01/1800Z 36.0N  86.0W   20 KT  25 MPH - Post Tropical (WSW Liberty,TN)

NWS National Hurricane Center Miami FL 1100 AM EDT Fri Aug 27, 2021 

Radar imagery from Grand Cayman and Cuba as well as satellite data continue to show an improvement in Ida’s overall structure this morning, with an increase in banding, the development of a small central dense overcast, and more recently an improved inner-core feature. Both the NOAA and Air Force reconnaissance aircraft reported that the pressure has fallen to around 996 mb, and the Air Force plane has measured flight-level and SFMR winds that support an initial intensity of 55 kt.

Although there is still some southwesterly shear over Ida, the outflow has begun to expand over the northeastern and southeastern portions of the circulation. The upper-level trough near the Yucatan peninsula that has been imparting the shear over Ida is forecast to weaken and move westward during the next 12 to 24 hours, which should result in a more favorable upper-level wind pattern. This, in combination with warm sea surface temperatures and a moist environment along the forecast track of the storm are expected to result in steady to rapid strengthening. Ida is now foreast to become a hurricane when it is near western Cuba and once it moves over the southeastern Gulf of Mexico a period of rapid strengthening is likely to begin, with the NHC intensity forecast explicitly calling for rapid intensification to major hurricane strength between 24 and 48 hours. The official intensity forecast is on the higher side of the intensity guidance but not quite as high as the slightly more aggressive CTCI, HWRF, and HCCA models. In addition to the increase in strength, the dynamical model guidance indicates that Ida’s wind field will grow larger as it moves over the Gulf of Mexico and this is reflected in the NHC wind radii forecast. In summary, there is a higher-than-normal confidence that a significant hurricane will impact a large portion of the northern Gulf coast by late this weekend and early next week.

Ida is moving northwestward or 320/13 kt. The track forecast reasoning is unchanged from before. A mid-level ridge over the western Atlantic is forecast to move westward and this should keep Ida on a general northwestward heading during the next 48-60 hours. This track will bring the storm across western Cuba later today, over the southeastern and central Gulf of Mexico on Saturday and Saturday night, to the coast of Louisiana by late Sunday. The track guidance is in remarkably good agreement with very little cross-track spread during the first 60 hours or so of the forecast period. After that time, Ida is forecast to reach the western portion of the ridge, which is expected to cause the storm to slow down and turn northward and then northeastward over the southeastern United States. The NHC track forecast is near or just east of the various consensus aids, in best agreement with the GFS ensemble mean. Although the small spread in the guidance through landfall increases the overall confidence in the track forecast, users are reminded to not focus on the exact details of the forecast track as storm surge, wind, and rainfall impacts will extend far from the center.

Key Messages:

  • 1. Life-threatening storm surge and hurricane conditions are expected later today and tonight in portions of western Cuba, including the Isle of Youth, where a Hurricane Warning is in effect. Life-threatening heavy rains, flash flooding and mudslides are expected across Jamaica, the Cayman Islands, and western Cuba, including the Isle of Youth.
  • 2. The risk of life-threatening storm surge inundation is increasing along the coasts of Louisiana, Mississippi, and Alabama. Inundation of 7 to 11 feet above ground level is possible within the area from Morgan City, Louisiana, to Ocean Springs, Mississippi, including Lake Borgne. Interests in these areas should follow any advice given by local officials.
  • 3. Ida is expected to be a dangerous major hurricane when it reaches the northern Gulf Coast on Sunday, and the risk of hurricane-force winds continues to increase, especially along portions of the Louisiana coast, including metropolitan New Orleans. Potentially devastating wind damage could occur where the core of Ida moves onshore.
  • 4. Ida is likely to produce heavy rainfall later Sunday into Monday across the central Gulf Coast from southeast Louisiana to coastal Mississippi and Alabama, as well as the Lower Mississippi Valley, resulting in considerable flash, urban, small stream, and riverine flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 20.7N  82.1W   55 KT  65 MPH - Tropical Storm (ESE Nueva Gerona,Cuba)
 12H  28/0000Z 22.2N  83.7W   65 KT  75 MPH - Category 1 (WSW La Coloma,Cuba)
 24H  28/1200Z 24.0N  85.8W   75 KT  85 MPH - Category 1 (WSW Key West,FL)
 36H  29/0000Z 25.9N  87.8W   90 KT 105 MPH - Category 2 (WSW Naples,FL)
 48H  29/1200Z 27.6N  89.7W  105 KT 120 MPH - Category 3 (ESE New Orleans,LA)
 60H  30/0000Z 29.0N  90.8W  105 KT 120 MPH - Category 3 (WSW Dulac,LA)
 72H  30/1200Z 30.3N  91.3W   60 KT  70 MPH - Tropical Storm (WSW Addis,LA)
 96H  31/1200Z 33.3N  90.2W   30 KT  35 MPH - Depression (ESE Cruger,MS)
120H  01/1200Z 35.2N  87.1W   20 KT  25 MPH - Post Tropical (WSW Pulaski,TN)

NWS National Hurricane Center Miami FL 1100 PM EDT Thu Aug 26, 2021 

The Air Force Hurricane Hunters have been investigating Ida this evening and found maximum flight-level winds of 47 kt at 2500 ft. This data along with numerous unflagged 35-kt SFMR winds supported raising the intensity to 35 kt earlier this evening. Since the aircraft departed Ida, there has been generally little change in the storm’s structure, so the initial intensity is held at 35 kt. Ida is an asymmetric tropical storm with most of the deep convection and stronger winds confined to the eastern half of the circulation. Both the NOAA and Air Force Hurricane Hunters will be investigating Ida Friday morning.

The storm has been wobbling around, but smoothing through the recent erratic motion yields an initial motion estimate of 320/10 kt. A mid-level ridge centered off the southeast U.S. coast is expected to shift westward on Friday and over the weekend. This feature should keep Ida moving in a general northwestward motion for the next 2 or 3 days, taking the core of the system over western Cuba Friday afternoon or evening and then across the southern and central Gulf of Mexico this weekend. Although there is some timing differences in the models, they are in fairly good agreement that Ida will make landfall in Louisiana late Sunday or early Monday. The GFS and ECMWF ensemble members basically span a similar region and are most concentrated across the state of Louisiana. Users are reminded to not focus on the exact forecast track as impacts will extend far from the center and the average 72-hour track error is around 120 miles.

There is some southwesterly vertical wind shear affecting Ida at the moment, which is the likely part of the reason the cloud pattern and wind field are asymmetric. However, the global model show the upper-level pattern becoming quite favorable late Friday and through the weekend. These more conducive winds aloft combined with very warm SSTs and abundant moisture is likely to result in steady or rapid intensification until Ida makes landfall in the U.S. The intensity guidance unanimously show Ida becoming a hurricane, but there is notable spread in how strong the system will become. Given the expected favorable environmental conditions for the storm, the NHC intensity forecast lies near the high end of the model guidance, in best agreement with the regional hurricane models. It is also worth noting that even though the global models are not particularly accurate in predicting tropical cyclone winds, the GFS and ECMWF show the minimum pressure falling more than 35 mb from the current conditions. Based on all of this information, there is higher-than-normal confidence that a significant hurricane will be approaching the Gulf coast late in the weekend.

Key Messages:

  • 1. Tropical storm conditions are expected in portions of the Cayman Islands tonight and in portions of western Cuba and the Isle of Youth Friday, where a dangerous storm surge is also possible in areas of onshore flow. Life-threatening heavy rains, flash flooding and mudslides are expected across Jamaica, the Cayman Islands, and western Cuba, including the Isle of Youth.
  • 2. There is an increasing risk of life-threatening storm surge inundation along the coasts of Louisiana, Mississippi, and Alabama, where a Storm Surge Watch is in effect. Interests in these areas should follow any advice given by local officials.
  • 3. There is an increasing risk of dangerous hurricane-force winds beginning Sunday along the portions of the coasts of Louisiana and Mississippi, including metropolitan New Orleans, where a Hurricane Watch is in effect.
  • 4. Ida is likely to produce heavy rainfall Sunday into Monday along the central Gulf coast resulting in flash, urban, small stream, and riverine flooding. Heavy rainfall and flooding impacts are likely along the central Gulf Coast Sunday into Monday.
FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 18.6N  80.5W   35 KT  40 MPH - Tropical Storm (ESE West Bay,Grand Cayman)
 12H  27/1200Z 19.9N  82.0W   45 KT  50 MPH - Tropical Storm (WNW West Bay,Grand Cayman)
 24H  28/0000Z 21.8N  83.9W   55 KT  65 MPH - Tropical Storm (ESE Finca Majagua,Cuba)
 36H  28/1200Z 23.8N  85.9W   65 KT  75 MPH - Category 1 (WSW Key West,FL)
 48H  29/0000Z 25.6N  88.0W   75 KT  85 MPH - Category 1 (WSW Naples,FL)
 60H  29/1200Z 27.3N  89.6W   85 KT 100 MPH - Category 2 (ESE New Orleans,LA)
 72H  30/0000Z 29.0N  90.6W   95 KT 110 MPH - Category 2 (WSW Timbalier Island,LA)
 96H  31/0000Z 32.0N  91.0W   45 KT  50 MPH - Tropical Storm (ESE Allen,MS)
120H  01/0000Z 33.9N  88.8W   25 KT  30 MPH - Depression (ENE Buena Vista,MS)

NWS National Hurricane Center Miami FL 500 PM EDT Thu Aug 26, 2021 

The overall satellite presentation of the tropical cyclone has continued to gradually improve today. Visible imagery and very recent observations from an Air Force Reserve reconnaissance aircraft indicate that the circulation has continued to become better defined. In addition, the convective activity has become a little better organized in a band around the northeastern and eastern portions of the circulation, and the system is likely near tropical storm strength. However, the initial intensity remains 30 kt pending the aircraft fully sampling the eastern portion of the circulation.

The initial motion estimate is northwestward or 325/12 kt. The 1200 UTC dynamical model guidance continues to take the system northwestward around the southwestern side of well-established deep-layer ridge over the western Atlantic. On the forecast track, the system is expected to move over portions of western Cuba late Friday, over the southeastern and central Gulf of Mexico on Saturday, and approach the northern Gulf coast on Sunday. Although the track guidance envelope has tightened this cycle, increasing confidence in the overall forecast scenario, some shifts in the track are still likely until the system consolidates and becomes better defined. Users are reminded to not focus on the exact forecast track as storm surge, wind, and rainfall hazards will extend far from the center, and the average NHC track forecast error at day 3 is around 120 miles. The lastest NHC track forecast is close to the previous official forecast, and lies between the TCVA and HCCA consensus aids.

There is some evidence of some light to moderate southerly shear over the system, but with the cyclone moving over the high ocean heat content waters of the northwestern Caribbean Sea the shear should not hinder intensification, with steady strengthening anticipated during the next 12 to 24 hours. Once the system moves over the Gulf of Mexico, it will be traversing a warm eddy, and this feature, combined with a favorable upper-level wind pattern and a moist atmosphere, is likely to result in steady to rapid strengthening on Saturday and Saturday night. The NHC intensity forecast again brings the system to near major hurricane strength when it approaches the northern Gulf coast on Sunday. This is supported by the HWRF and CTCI models, and the global model guidance that has consistently showed significant deepening of the system over the Gulf of Mexico over the past several model cycles. Therefore, as mentioned this morning, there is higher-than-normal confidence that a strengthening tropical cyclone will be moving over the Gulf of Mexico this weekend.

Key Messages:

  • 1. Tropical storm conditions are expected in portions of the Cayman Islands tonight and in portions of western Cuba and the Isle of Youth Friday. Dangerous storm surge is possible Friday in portions of western Cuba, including the Isle of Youth, in areas of onshore flow.
  • 2. Life-threatening heavy rains, flash flooding and mudslides are expected across Jamaica, the Cayman Islands, and western Cuba, including the Isle of Youth.
  • 3. The system is forecast to approach the northern Gulf coast at or near major hurricane intensity on Sunday, where there is an increasing risk of life-threatening storm surge, damaging hurricane-force winds, and heavy rainfall Sunday and Monday, especially along the coast of Louisiana. Storm Surge and Hurricane watches will likely be issued for a portion of this area later tonight or Friday morning. Interests in these areas should closely monitor the progress of this system and follow any advice given by local officials.
FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 18.0N  79.8W   30 KT  35 MPH - Depression (WSW Negril,Jamaica)
 12H  27/0600Z 19.7N  81.0W   45 KT  50 MPH - Tropical Storm (ENE West Bay,Grand Cayman)
 24H  27/1800Z 21.7N  82.8W   55 KT  65 MPH - Tropical Storm (WNW La Ceiba,Cuba)
 36H  28/0600Z 23.7N  84.8W   60 KT  70 MPH - Tropical Storm (WSW Key WSest,FL)
 48H  28/1800Z 25.6N  87.0W   70 KT  80 MPH - Category 1 (WSW Naples,FL)
 60H  29/0600Z 27.2N  88.8W   85 KT 100 MPH - Category 2 (ESE New Orlens,LA)
 72H  29/1800Z 28.9N  90.4W   95 KT 110 MPH - Category 2 (WSW Port Fourchon,LA)
 96H  30/1800Z 31.9N  91.4W   50 KT  60 MPH - Tropical Storm (WNW Helena,LA)
120H  31/1800Z 34.6N  90.0W   25 KT  30 MPH - Post Tropical (WSW Senatobia,MS)

NWS National Hurricane Center Miami FL 1100 AM EDT Thu Aug 26, 2021 

Early morning visible satellite imagery shows that the circulation associated with the area of low pressure over west-central Caribbean Sea has become better defined. There has also been an increase in the organization of the associated convective activity, and based on consensus Dvorak T-numbers of 2.0 from TAFB and SAB, advisories are being initiated on a tropical depression. The initial intensity is set at 30 kt, in agreement with the subjective satellite estimates. The official reporting station in Kingston, Jamaica, has reported sustained winds of 25 kt with gusts to 35 kt during the past couple of hours. An Air Force Reserve reconnaissance aircraft is scheduled to be in the system later this afternoon to provide more information on the system’s structure and intensity.

The depression is moving northwestward or 325/11 kt, however the initial motion is a bit more uncertain than normal since the low- level center has only recently formed. The cyclone is forecast to move steadily northwestward around the southwestern portion of a deep-layer ridge centered over the western Atlantic. This track should bring the center near or over western Cuba late Friday, over the southeastern and central Gulf of Mexico Friday night and Saturday, and have the center approach the northern Gulf coast on Sunday. The track guidance is in relatively good agreement, however the average NHC track forecast error at day 4 is around 175 miles, so users should not focus on the details of the long range track forecast. Some shifts in the track are likely until the system consolidates and becomes better defined. The NHC track is near the various consensus model aids and is in best agreement with the GFS ensemble mean. The depression will be moving over the high ocean heat content waters of the northwestern Caribbean Sea during the next 24-36 hours. This, in combination with low vertical wind shear and a moist environment, should allow for steady strengthening.

The depression is forecast to become a tropical storm later today or tonight, and could approach hurricane strength as it passes near or over western Cuba. Once the system moves into the Gulf of Mexico, conditions are expected to be conducive for additional strengthening, and rapid intensification is explicitly shown in the NHC forecast between 48 and 72 hours. The NHC intensity forecast brings the system near major hurricane strength when it approaches the northern Gulf coast on Sunday. This forecast is supported by the HWRF and CTCI models, and the GFS, ECMWF, and UKMET global model guidance, which all significantly deepen the cyclone over the Gulf of Mexico. As a result, there is higher-than-normal confidence that a strengthening tropical cyclone will be moving over the Gulf this weekend.

Key Messages:

  • 1. Tropical storm conditions are likely in portions of the Cayman Islands tonight and western Cuba Friday and Friday night, with dangerous storm surge possible in portions of western Cuba, including the Isle of Youth, in areas of onshore flow.
  • 2. The system is expected to produce life-threatening heavy rains, flash flooding and mudslides across Jamaica, the Cayman Islands, western Cuba, including the Isle of Youth and northeastern portions of the Yucatan Peninsula.
  • 3. This system is forecast to approach the northern Gulf Coast at or near major hurricane intensity on Sunday, although the forecast uncertainty is larger than usual since the system is just forming. There is a risk of life-threatening storm surge, damaging hurricane-force winds, and heavy rainfall Sunday and Monday along the northern Gulf Coast from the Florida Panhandle to the upper Texas coast, with the greatest risk along the coast of Louisiana. Interests in these areas should closely monitor the progress of this system and ensure they have their hurricane plan in place.
FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 16.9N  79.2W   30 KT  35 MPH - Depression (WSW Negril,Jamaica)
 12H  27/0000Z 18.2N  80.4W   35 KT  40 MPH - Tropical Storm (WSW Negril,Jamaica)
 24H  27/1200Z 20.3N  82.0W   45 KT  50 MPH - Tropical Storm (ESE Nueva Gerona,Cuba)
 36H  28/0000Z 22.5N  83.9W   55 KT  65 MPH - Tropical Storm (WNW Cabeza,Cuba)
 48H  28/1200Z 24.4N  86.0W   65 KT  75 MPH - Category 1 (WSW Key West,FL)
 60H  29/0000Z 26.1N  88.1W   80 KT  90 MPH - Category 1 (ESE Naples,FL)
 72H  29/1200Z 27.7N  90.0W   95 KT 110 MPH - Category 2 (ESE New Orleans,LA)
 96H  30/1200Z 30.5N  92.0W   70 KT  80 MPH - Category 1 (WNW  Leonville,LA)
120H  31/1200Z 33.7N  91.2W   30 KT  35 MPH - Depression (ENE Arkansas City,AR)

NWS National Hurricane Center Miami FL 800 PM EDT Wed Aug 25, 2021

Corrected 48-h formation chance in first paragraph

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

  • 1. A broad area of low pressure is expected to form over the western Caribbean Sea during the next day or so from a tropical wave currently located north of Colombia. Environmental conditions are forecast to be conducive for development, and a tropical depression or tropical storm is likely to form late this week or over the weekend. The system is expected to move northwestward over the northwestern Caribbean Sea and near or across the Yucatan Peninsula of Mexico on Friday and into the Gulf of Mexico this weekend, where conditions are expected to be favorable for additional development. Regardless of development, heavy rainfall and flooding will be possible through the weekend in portions of Central America and the Yucatan Peninsula. In addition, this system could bring dangerous impacts from storm surge, wind, and heavy rainfall to portions of the coasts of Louisiana, Texas, and the Mexican state of Tamaulipas late this weekend and early next week. However, uncertainty remains large since the system has yet to form. Interests in these areas should closely monitor the progress of this system and ensure they have their hurricane plan in place. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system Thursday afternoon, if necessary. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…80 percent.
  • 2. A broad trough of low pressure is producing disorganized showers and thunderstorms over the central tropical Atlantic about 650 miles east-southeast of Bermuda. Only slow development of this system is expected during the next day or so due to unfavorable upper-level winds. Afterwards, environmental conditions are forecast to become more conducive for development, and a tropical depression is likely to form late this week or this weekend while the system turns eastward over the central Atlantic. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…80 percent.
  • 3. A tropical wave over the far eastern tropical Atlantic located several hundred miles west-southwest of the Cabo Verde Islands is producing disorganized showers and thunderstorms. Some development of this system is possible over the next several days while it moves west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. Upper-level winds are forecast to become less conducive for development by early next week. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low...30 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Tue Aug 24, 2021

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

  • 1. A broad area of low pressure is expected to form over the southwestern Caribbean Sea in a couple of days from a tropical wave currently located over the central Caribbean Sea. Environmental conditions are forecast to be conducive for development of the low if it remains over water, and a tropical depression could form late this week or this weekend while the system moves northwestward over the northwestern Caribbean Sea, across the Yucatan Peninsula of Mexico, and into the southwestern Gulf of Mexico by Sunday. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium...60 percent.
  • 2. A broad trough of low pressure is producing disorganized showers and thunderstorms over the central tropical Atlantic about 1000 miles east-northeast of the northern Leeward Islands. Little development of this system is expected during the next day or two due to unfavorable upper-level winds. Afterwards, environmental conditions are expected to become more conducive for development, and a tropical depression is likely to form by the end of the week while the system turns eastward over the central Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high…70 percent.
  • 3. A tropical wave over the far eastern tropical Atlantic located several hundred miles southwest of the Cabo Verde Islands is producing a concentrated area of showers and thunderstorms. Some development of this system is possible over the next several days while it moves west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. Upper-level winds are forecast to become less conducive for development by the weekend. * Formation chance through 48 hours…low…20 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Tue Aug 24, 2021

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

  • 1. A broad area of low pressure is expected to form over the southwestern Caribbean Sea in a couple of days from a tropical wave currently located over the central Caribbean Sea. Environmental conditions are forecast to be conducive for development of the low if it remains over water, and a tropical depression could form late this week or this weekend while the system moves northwestward over the northwestern Caribbean Sea, across the Yucatan Peninsula of Mexico, and into the southwestern Gulf of Mexico by Sunday. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. A broad trough of low pressure is producing disorganized showers and thunderstorms over the central tropical Atlantic almost 1000 miles east-northeast of the northern Leeward Islands. Little development of this system is expected during the next day or two due while it moves northwestward at about 15 mph over marginally conducive ocean temperatures and is affected by strong upper-level winds. Afterwards, environmental conditions are expected to become more conducive for development, and a tropical depression is likely to form by the end of the week while the system turns eastward over the central Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high...70 percent.
  • 3. Another tropical wave over the far eastern tropical Atlantic located a few hundred miles south-southwest of the Cabo Verde Islands is producing a concentrated area of showers and thunderstorms. Some development of this system is possible over the next several days while it moves westward to west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. Upper-level winds are forecast to become less conducive for development by the weekend. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Tue Aug 24, 2021

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

The Weather Prediction Center has issued the last Public Advisory on Post-Tropical Cyclone Henri, moving offshore of eastern Massachusetts.

  • 1. A broad trough of low pressure is producing disorganized showers and thunderstorms over the central tropical Atlantic about 900 miles east-northeast of the northern Leeward Islands. Little development of this system is expected during the next day or two due while it moves northwestward at about 15 mph over marginally conducive ocean temperatures and is affected by strong upper-level winds. Afterwards, environmental conditions are expected to become more favorable for gradual development, and a tropical depression could form by the end of the week while the system turns eastward over the central Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. A broad area of low pressure is expected to form over the southwestern Caribbean Sea in a few days from a tropical wave currently located over the eastern Caribbean Sea. Environmental conditions are forecast to be conducive for development of the low, and a tropical depression could form late this week or this weekend while the system moves northwestward over the northwestern Caribbean Sea, across the Yucatan Peninsula of Mexico, and into the southwestern Gulf of Mexico by Sunday. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…60 percent.
  • 3. Another tropical wave over the far eastern tropical Atlantic located about 400 miles south-southwest of the Cabo Verde Islands is producing a concentrated area of showers and thunderstorms. Some development of this system is possible over the next several days while it moves westward to west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. Upper-level winds are forecast to become less conducive for development by the weekend. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Mon Aug 23 2021

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

The Weather Prediction Center is issuing Public Advisories on Post-Tropical Cyclone Henri, located inland near southern New England.

  • 1. A broad low pressure area is producing disorganized showers and thunderstorms over the east-central tropical Atlantic more than 800 miles west of the Cabo Verde Islands. Little development is expected during the next couple of days due to only marginally conducive ocean temperatures. Thereafter, however, some gradual development is possible through the end of the week while the system moves northwestward to northward at 10 to 15 mph over the central Atlantic. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. A tropical wave over the eastern Caribbean Sea is expected to form a broad area of low pressure over the southwestern Caribbean Sea by late week. Thereafter, environmental conditions are forecast to be favorable for gradual development while the system moves west-northwestward to northwestward over the northwestern Caribbean Sea. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…50 percent.
  • 3. A low pressure area over the far eastern tropical Atlantic about 500 miles south-southeast of the Cabo Verde Islands is producing disorganized showers and thunderstorms. Some slow development is possible over the next several days while the disturbance moves westward to west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Mon Aug 23 2021

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

The Weather Prediction Center is issuing Public Advisories on Tropical Depression Henri, located inland over southern New England.

  • 1. A broad low pressure system is producing disorganized showers and thunderstorms over the eastern tropical Atlantic more than 700 miles west of the Cabo Verde Islands. Little development is expected during the next couple of days due to only marginally conducive ocean temperatures. Thereafter, however, some gradual development is possible by the middle to latter part of the week while the system moves northwestward at 10 to 15 mph over the central Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.
  • 2. A tropical wave located over the eastern Caribbean Sea is expected to form a broad area of low pressure over the southwestern Caribbean Sea by late week. Thereafter, environmental conditions are forecast to become favorable for gradual development while the system moves west-northwestward over the northwestern Caribbean Sea. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sat Aug 21, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Henri, located several hundred miles south-southeast of Long Island, New York, and has issued the last advisory on the Remnants of Grace, located inland over central Mexico.

  • 1. Disorganized shower activity over the eastern tropical Atlantic is associated with two interacting tropical waves near and to the southwest of the Cabo Verde Islands. Little, if any, development of this broad system is anticipated over the next couple of days. However, some gradual development is possible later on by the middle of next week as the system moves northwestward at 10 to 15 mph. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…10 percent.

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