Potential Storm Surge Flooding Map last updated Wed, 25 Sep 2024 22:07:58 GMT

Probabilistic Storm Surge Graphics last updated Wed, 25 Sep 2024 21:33:35 GMT

...HELENE STRENGTHENING... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... As of 4:00 PM CDT Wed Sep 25 the center of Helene was located near 22.5, -86.6 with movement N at 12 mph. The minimum central pressure was 978 mb with maximum sustained winds of about 85 mph.

Issued at 400 PM CDT Wed Sep 25 2024 000 WTNT34 KNHC 252107 CCA TCPAT4 BULLETIN Hurricane Helene Advisory Number 10...Corrected NWS National Hurricane Center Miami FL AL092024 400 PM CDT Wed Sep 25 2024 Corrected to remove Storm Surge Watch area in the summary ...HELENE STRENGTHENING... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...22.5N 86.6W ABOUT 460 MI...735 KM SW OF TAMPA FLORIDA ABOUT 505 MI...815 KM SSW OF APALACHICOLA FLORIDA MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H PRESENT MOVEMENT...N OR 355 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Storm Surge Watch east of Mexico Beach to Indian Pass has been upgraded to a Storm Surge Warning. The Tropical Storm Watch north of South Santee River to Little River Inlet has been upgraded to a Tropical Storm Warning. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Mexico Beach eastward and southward to Flamingo * Tampa Bay * Charlotte Harbor A Hurricane Warning is in effect for... * Anclote River to Mexico Beach * Cabo Catoche to Tulum, Mexico including Cozumel A Hurricane Watch is in effect for... * Cuban province of Pinar del Rio * Englewood to Anclote River, including Tampa Bay A Tropical Storm Warning is in effect for... * Florida Keys, including the Dry Tortugas * Flamingo to Anclote River, including Tampa Bay * West of Mexico Beach to the Okaloosa/Walton County Line * Flamingo northward to Little River Inlet * Lake Okeechobee * Rio Lagartos to Cabo Catoche, Mexico * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within the next 36 hours. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 400 PM CDT (2100 UTC), the center of Hurricane Helene was located near latitude 22.5 North, longitude 86.6 West. Helene is moving toward the north near 12 mph (19 km/h). A northward or north-northeastward motion at a faster forward speed is expected during the next 36 hours. On the forecast track, Helene will move across the eastern Gulf of Mexico tonight and Thursday and cross the Florida Big Bend coast Thursday evening. After landfall, Helene is expected to turn northwestward and slow down over the Tennessee Valley on Friday and Saturday. Maximum sustained winds are near 85 mph (140 km/h) with higher gusts. Strengthening is forecast, and Helene is expected to be a major hurricane when it reaches the Florida Big Bend coast Thursday evening. Weakening is expected after landfall, but Helene's fast forward speed will allow strong, damaging winds, especially in gusts, to penetrate well inland across the southeastern United States, including over the higher terrain of the southern Appalachians. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 345 miles (555 km). The estimated minimum central pressure is 978 mb (28.88 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for Helene can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC and on the web at hurricanes.gov/text/MIATCDAT4.shtml STORM SURGE: The combination of a life-threatening storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Carrabelle, FL to Suwannee River, FL...15-20 ft Apalachicola, FL to Carrabelle, FL...10-15 ft Suwannee River, FL to Chassahowitzka, FL...10-15 ft Chassahowitzka, FL to Anclote River, FL...8-12 ft Indian Pass, FL to Apalachicola, FL...6-10 ft Anclote River, FL to Middle of Longboat Key, FL...5-8 ft Tampa Bay...5-8 ft Middle of Longboat Key, FL to Englewood, FL...4-7 ft East of Mexico Beach, FL to Indian Pass, FL...3-5 ft Englewood, FL to Flamingo, FL...3-5 ft Charlotte Harbor...3-5 ft For a complete depiction of areas at risk of storm surge inundation, please see the National Weather Service Peak Storm Surge Graphic, available at hurricanes.gov/graphics_at4.shtml?peakSurge. Storm surge could raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore winds along the southern coast of Pinar del Rio, Cuba, including the Isle of Youth. Storm surge could raise water levels by as much as 3 to 5 feet above ground level in areas of onshore winds within the warning area along the north coast of the Yucatan Peninsula. WIND: Hurricane conditions are expected within the U.S. hurricane warning area late Thursday, with tropical storm conditions beginning Thursday morning. Tropical storm conditions are expected in southern Florida later this evening and will spread northward across the rest of Florida, Georgia, and South Carolina through Thursday night. Hurricane conditions, especially in gusts, are expected in the hurricane warning area in Mexico during the next several hours. Tropical storm conditions are occurring in the warning area in Cuba, and hurricane conditions are possible for the western portion of Cuba this evening. RAINFALL: Hurricane Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba, the Cayman Islands and the northeast Yucatan Peninsula, with isolated totals around 12 inches. This rainfall brings a risk of considerable flooding. Over portions of the Southeastern U.S. into the Southern Appalachians, Helene is expected to produce total rain accumulations of 6 to 12 inches with isolated totals around 18 inches. This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Landslides are possible in steep terrain across the southern Appalachians. For a complete depiction of forecast rainfall associated with Hurricane Helene, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero. TORNADOES: A tornado or two may occur tonight over parts of the Florida Peninsula and southern Alabama. The risk of tornadoes will increase on Thursday, expanding northward across Florida into parts of Georgia and South Carolina. SURF: Swells generated by Helene will affect the southern coast of Cuba and the Yucatan Peninsula of Mexico during the next couple of days. Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast later today and Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 700 PM CDT. Next complete advisory at 1000 PM CDT. $$ Forecaster Berg

Storm Surge Watch/Warning Map last updated Wed, 25 Sep 2024 20:59:22 GMT

Issued at 2100 UTC WED SEP 25 2024 000 WTNT24 KNHC 252055 TCMAT4 HURRICANE HELENE FORECAST/ADVISORY NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 2100 UTC WED SEP 25 2024 HURRICANE CENTER LOCATED NEAR 22.5N 86.6W AT 25/2100Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTH OR 355 DEGREES AT 10 KT ESTIMATED MINIMUM CENTRAL PRESSURE 978 MB MAX SUSTAINED WINDS 75 KT WITH GUSTS TO 90 KT. 64 KT....... 20NE 20SE 0SW 0NW. 50 KT....... 60NE 60SE 40SW 40NW. 34 KT.......210NE 300SE 90SW 120NW. 12 FT SEAS..180NE 210SE 90SW 120NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 22.5N 86.6W AT 25/2100Z AT 25/1800Z CENTER WAS LOCATED NEAR 22.0N 86.4W FORECAST VALID 26/0600Z 24.1N 86.2W MAX WIND 95 KT...GUSTS 115 KT. 64 KT... 30NE 40SE 25SW 20NW. 50 KT... 80NE 80SE 50SW 40NW. 34 KT...270NE 270SE 120SW 120NW. FORECAST VALID 26/1800Z 27.4N 85.2W MAX WIND 115 KT...GUSTS 140 KT. 64 KT... 40NE 50SE 25SW 20NW. 50 KT... 80NE 100SE 50SW 40NW. 34 KT...270NE 270SE 140SW 140NW. FORECAST VALID 27/0600Z 32.1N 84.6W...INLAND MAX WIND 70 KT...GUSTS 90 KT. 64 KT... 20NE 25SE 0SW 0NW. 50 KT... 40NE 50SE 20SW 20NW. 34 KT...270NE 270SE 70SW 60NW. FORECAST VALID 27/1800Z 36.1N 86.0W...POST-TROP/EXTRATROP MAX WIND 35 KT...GUSTS 55 KT. 34 KT... 50NE 30SE 0SW 0NW. FORECAST VALID 28/0600Z 37.1N 88.1W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 40 KT. FORECAST VALID 28/1800Z 36.8N 88.7W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 125 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 29/1800Z 37.0N 88.0W...POST-TROP/EXTRATROP MAX WIND 15 KT...GUSTS 20 KT. OUTLOOK VALID 30/1800Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 22.5N 86.6W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 26/0000Z NEXT ADVISORY AT 26/0300Z $$ FORECASTER BERG

Issued at 400 PM CDT Wed Sep 25 2024 000 WTNT44 KNHC 252056 TCDAT4 Hurricane Helene Discussion Number 10 NWS National Hurricane Center Miami FL AL092024 400 PM CDT Wed Sep 25 2024 A ragged eye is becoming apparent in visible satellite imagery and has also been observed in recent radar data from Cancun and western Cuba. Based on the improved structure, the initial intensity is set at 75 kt, which is at the high end of the satellite intensity estimates. This is also supported by the earlier Air Force Reserve reconnaissance mission, which measured a peak 700-mb flight-level wind of 81 kt. Helene has turned northward (355/9 kt) and is expected to accelerate toward the north or north-northeast during the next 24-36 hours as it moves across the Gulf of Mexico and crosses the Florida Big Bend coast Thursday evening. After landfall, the system is forecast to interact with a deep-layer trough to the west and turn northwestward with a decrease in speed over the Tennessee Valley. The environment appears primed for significant strengthening while Helene moves across the Gulf of Mexico. The forecast track more or less runs along the axis of the Loop Current during the next 24 hours, where ocean temperatures are about 30 degrees Celsius. In addition, Helene will be moving through an environment of low vertical shear and strong upper-level divergence. Some of the Rapid Intensification (RI) indices, particular DTOPS, respond to this environment by indicating at least a 90 percent chance of a 35-kt increase in intensity over the next 24 hours. The NHC intensity forecast now shows an intensity of 115 kt (Category 4) at 24 hours, which is mirrored by several of the regional hurricane models and the SHIPS guidance. It should be noted that additional strengthening is possible beyond 24 hours before Helene makes landfall Thursday evening. Helene is forecast to be a large major hurricane when it reaches the Big Bend coast of Florida. As a result, storm surge, wind, and rainfall impacts will extend well away from the center and outside the forecast cone, particularly on the east side. In addition, the fast forward speed when Helene moves inland will result in a far inland penetration of strong winds over parts of the southeastern United States, including strong gusts over higher terrain of the southern Appalachians. A higher-than-normal gust factor has been indicated in the official forecast while Helene is inland. KEY MESSAGES: 1. A catastrophic and deadly storm surge is likely along portions of the Florida Big Bend coast, where inundation could reach as high as 20 feet above ground level, along with destructive waves. There is also a danger of life-threatening storm surge along the remainder of the west coast of the Florida Peninsula. Residents in those areas should follow advice given by local officials and evacuate if told to do so. 2. Potentially catastrophic hurricane-force winds are expected within the eyewall of Helene when it makes landfall in the Florida Big Bend region late Thursday. Preparations to protect life and property should be completed by early Thursday before tropical storm conditions arrive. Damaging and life-threatening hurricane-force winds, especially in gusts, will penetrate well inland over portions of northern Florida and southern Georgia late Thursday and Thursday night where Hurricane Warnings are in effect. Strong wind gusts are also likely farther north across portions of northern Georgia and the Carolinas, particularly over the higher terrain of the southern Appalachians. 3. Catastrophic and life-threatening flash and urban flooding, including landslides, is expected across portions of the southern Appalachians through Friday. Considerable to locally catastrophic flash and urban flooding is likely for northwestern and northern Florida and the Southeast through Friday. Widespread minor to moderate river flooding is likely, and isolated major river flooding is possible. 4. Hurricane and tropical storm conditions are expected over northeastern portions of the Yucatan Peninsula of Mexico this evening where Tropical Storm and Hurricane Warnings are in effect. Tropical storm conditions are occurring over portions of western Cuba within the Tropical Storm Warning area, and hurricane conditions are possible this evening within the Hurricane Watch area. Helene will bring heavy rain to portions of the western Caribbean with potentially significant flooding across western Cuba and the northeastern Yucatan Peninsula into early Thursday. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 22.5N 86.6W 75 KT 85 MPH 12H 26/0600Z 24.1N 86.2W 95 KT 110 MPH 24H 26/1800Z 27.4N 85.2W 115 KT 130 MPH 36H 27/0600Z 32.1N 84.6W 70 KT 80 MPH...INLAND 48H 27/1800Z 36.1N 86.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 60H 28/0600Z 37.1N 88.1W 25 KT 30 MPH...POST-TROP/EXTRATROP 72H 28/1800Z 36.8N 88.7W 20 KT 25 MPH...POST-TROP/EXTRATROP 96H 29/1800Z 37.0N 88.0W 15 KT 15 MPH...POST-TROP/EXTRATROP 120H 30/1800Z...DISSIPATED $$ Forecaster Berg

...HELENE STRENGTHENING... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... As of 4:00 PM CDT Wed Sep 25 the center of Helene was located near 22.5, -86.6 with movement N at 12 mph. The minimum central pressure was 978 mb with maximum sustained winds of about 85 mph.

Issued at 400 PM CDT Wed Sep 25 2024 000 WTNT34 KNHC 252056 TCPAT4 BULLETIN Hurricane Helene Advisory Number 10 NWS National Hurricane Center Miami FL AL092024 400 PM CDT Wed Sep 25 2024 ...HELENE STRENGTHENING... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...22.5N 86.6W ABOUT 460 MI...735 KM SW OF TAMPA FLORIDA ABOUT 505 MI...815 KM SSW OF APALACHICOLA FLORIDA MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H PRESENT MOVEMENT...N OR 355 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Storm Surge Watch east of Mexico Beach to Indian Pass has been upgraded to a Storm Surge Warning. The Tropical Storm Watch north of South Santee River to Little River Inlet has been upgraded to a Tropical Storm Warning. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Mexico Beach eastward and southward to Flamingo * Tampa Bay * Charlotte Harbor A Hurricane Warning is in effect for... * Anclote River to Mexico Beach * Cabo Catoche to Tulum, Mexico including Cozumel A Storm Surge Watch is in effect for... * West of Indian Pass to Mexico Beach A Hurricane Watch is in effect for... * Cuban province of Pinar del Rio * Englewood to Anclote River, including Tampa Bay A Tropical Storm Warning is in effect for... * Florida Keys, including the Dry Tortugas * Flamingo to Anclote River, including Tampa Bay * West of Mexico Beach to the Okaloosa/Walton County Line * Flamingo northward to Little River Inlet * Lake Okeechobee * Rio Lagartos to Cabo Catoche, Mexico * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within the next 36 hours. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 400 PM CDT (2100 UTC), the center of Hurricane Helene was located near latitude 22.5 North, longitude 86.6 West. Helene is moving toward the north near 12 mph (19 km/h). A northward or north-northeastward motion at a faster forward speed is expected during the next 36 hours. On the forecast track, Helene will move across the eastern Gulf of Mexico tonight and Thursday and cross the Florida Big Bend coast Thursday evening. After landfall, Helene is expected to turn northwestward and slow down over the Tennessee Valley on Friday and Saturday. Maximum sustained winds are near 85 mph (140 km/h) with higher gusts. Strengthening is forecast, and Helene is expected to be a major hurricane when it reaches the Florida Big Bend coast Thursday evening. Weakening is expected after landfall, but Helene's fast forward speed will allow strong, damaging winds, especially in gusts, to penetrate well inland across the southeastern United States, including over the higher terrain of the southern Appalachians. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 345 miles (555 km). The estimated minimum central pressure is 978 mb (28.88 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for Helene can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC and on the web at hurricanes.gov/text/MIATCDAT4.shtml STORM SURGE: The combination of a life-threatening storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Carrabelle, FL to Suwannee River, FL...15-20 ft Apalachicola, FL to Carrabelle, FL...10-15 ft Suwannee River, FL to Chassahowitzka, FL...10-15 ft Chassahowitzka, FL to Anclote River, FL...8-12 ft Indian Pass, FL to Apalachicola, FL...6-10 ft Anclote River, FL to Middle of Longboat Key, FL...5-8 ft Tampa Bay...5-8 ft Middle of Longboat Key, FL to Englewood, FL...4-7 ft East of Mexico Beach, FL to Indian Pass, FL...3-5 ft Englewood, FL to Flamingo, FL...3-5 ft Charlotte Harbor...3-5 ft For a complete depiction of areas at risk of storm surge inundation, please see the National Weather Service Peak Storm Surge Graphic, available at hurricanes.gov/graphics_at4.shtml?peakSurge. Storm surge could raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore winds along the southern coast of Pinar del Rio, Cuba, including the Isle of Youth. Storm surge could raise water levels by as much as 3 to 5 feet above ground level in areas of onshore winds within the warning area along the north coast of the Yucatan Peninsula. WIND: Hurricane conditions are expected within the U.S. hurricane warning area late Thursday, with tropical storm conditions beginning Thursday morning. Tropical storm conditions are expected in southern Florida later this evening and will spread northward across the rest of Florida, Georgia, and South Carolina through Thursday night. Hurricane conditions, especially in gusts, are expected in the hurricane warning area in Mexico during the next several hours. Tropical storm conditions are occurring in the warning area in Cuba, and hurricane conditions are possible for the western portion of Cuba this evening. RAINFALL: Hurricane Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba, the Cayman Islands and the northeast Yucatan Peninsula, with isolated totals around 12 inches. This rainfall brings a risk of considerable flooding. Over portions of the Southeastern U.S. into the Southern Appalachians, Helene is expected to produce total rain accumulations of 6 to 12 inches with isolated totals around 18 inches. This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Landslides are possible in steep terrain across the southern Appalachians. For a complete depiction of forecast rainfall associated with Hurricane Helene, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero. TORNADOES: A tornado or two may occur tonight over parts of the Florida Peninsula and southern Alabama. The risk of tornadoes will increase on Thursday, expanding northward across Florida into parts of Georgia and South Carolina. SURF: Swells generated by Helene will affect the southern coast of Cuba and the Yucatan Peninsula of Mexico during the next couple of days. Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast later today and Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 700 PM CDT. Next complete advisory at 1000 PM CDT. $$ Forecaster Berg

Issued at 2100 UTC WED SEP 25 2024 000 FONT14 KNHC 252056 PWSAT4 HURRICANE HELENE WIND SPEED PROBABILITIES NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 2100 UTC WED SEP 25 2024 AT 2100Z THE CENTER OF HURRICANE HELENE WAS LOCATED NEAR LATITUDE 22.5 NORTH...LONGITUDE 86.6 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 75 KTS...85 MPH...140 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 18Z WED AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 18Z WED 06Z THU 18Z THU 06Z FRI 18Z FRI 18Z SAT 18Z SUN PERIODS TO TO TO TO TO TO TO 06Z THU 18Z THU 06Z FRI 18Z FRI 18Z SAT 18Z SUN 18Z MON FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT CHARLOTTE NC 34 X X( X) 3( 3) 1( 4) X( 4) X( 4) X( 4) FLORENCE SC 34 X X( X) 3( 3) 1( 4) X( 4) X( 4) X( 4) COLUMBIA SC 34 X X( X) 7( 7) 1( 8) X( 8) X( 8) X( 8) LITTLE RIVER 34 X X( X) 3( 3) 1( 4) X( 4) X( 4) X( 4) MYRTLE BEACH 34 X X( X) 5( 5) 1( 6) X( 6) X( 6) X( 6) GEORGETOWN SC 34 X X( X) 4( 4) X( 4) X( 4) X( 4) X( 4) CHARLESTON SC 34 X X( X) 15(15) 1(16) X(16) X(16) X(16) BEAUFORT MCAS 34 X X( X) 27(27) 2(29) X(29) X(29) X(29) ATLANTA GA 34 X X( X) 33(33) 36(69) X(69) X(69) X(69) AUGUSTA GA 34 X X( X) 18(18) 3(21) X(21) X(21) X(21) SAVANNAH GA 34 X X( X) 16(16) 1(17) X(17) X(17) X(17) KINGS BAY GA 34 X 8( 8) 43(51) 1(52) X(52) X(52) X(52) KINGS BAY GA 50 X X( X) 4( 4) X( 4) X( 4) X( 4) X( 4) WAYCROSS GA 34 X 6( 6) 52(58) 1(59) X(59) X(59) X(59) WAYCROSS GA 50 X X( X) 4( 4) X( 4) X( 4) X( 4) X( 4) MAYPORT NS FL 34 X 9( 9) 40(49) 1(50) X(50) X(50) X(50) MAYPORT NS FL 50 X X( X) 3( 3) X( 3) X( 3) X( 3) X( 3) JACKSONVILLE 34 X 7( 7) 31(38) X(38) X(38) X(38) X(38) GAINESVILLE FL 34 X 18(18) 46(64) X(64) X(64) X(64) X(64) GAINESVILLE FL 50 X X( X) 4( 4) X( 4) X( 4) X( 4) X( 4) DAYTONA BEACH 34 X 9( 9) 14(23) X(23) X(23) X(23) X(23) THE VILLAGES 34 X 27(27) 26(53) X(53) X(53) X(53) X(53) ORLANDO FL 34 X 17(17) 12(29) X(29) X(29) X(29) X(29) COCOA BEACH FL 34 X 18(18) 13(31) X(31) X(31) X(31) X(31) PATRICK AFB 34 X 19(19) 13(32) X(32) X(32) X(32) X(32) FT PIERCE FL 34 X 16(16) 7(23) X(23) X(23) X(23) X(23) W PALM BEACH 34 X 12(12) 2(14) X(14) X(14) X(14) X(14) FT LAUDERDALE 34 X 11(11) 1(12) X(12) X(12) X(12) X(12) MIAMI FL 34 X 7( 7) X( 7) X( 7) X( 7) X( 7) X( 7) HOMESTEAD ARB 34 X 7( 7) X( 7) X( 7) X( 7) X( 7) X( 7) MARATHON FL 34 7 15(22) X(22) X(22) X(22) X(22) X(22) KEY WEST FL 34 19 24(43) X(43) X(43) X(43) X(43) X(43) NAPLES FL 34 8 44(52) 2(54) X(54) X(54) X(54) X(54) FT MYERS FL 34 5 40(45) 1(46) X(46) X(46) X(46) X(46) VENICE FL 34 8 66(74) 4(78) X(78) X(78) X(78) X(78) VENICE FL 50 X 7( 7) 1( 8) X( 8) X( 8) X( 8) X( 8) TAMPA FL 34 2 65(67) 12(79) X(79) X(79) X(79) X(79) TAMPA FL 50 X 6( 6) 4(10) X(10) X(10) X(10) X(10) TAMPA FL 64 X X( X) 1( 1) X( 1) X( 1) X( 1) X( 1) CEDAR KEY FL 34 X 57(57) 31(88) X(88) X(88) X(88) X(88) CEDAR KEY FL 50 X 6( 6) 19(25) X(25) X(25) X(25) X(25) CEDAR KEY FL 64 X X( X) 4( 4) X( 4) X( 4) X( 4) X( 4) TALLAHASSEE FL 34 X 16(16) 81(97) X(97) X(97) X(97) X(97) TALLAHASSEE FL 50 X 1( 1) 64(65) 1(66) X(66) X(66) X(66) TALLAHASSEE FL 64 X X( X) 25(25) 1(26) X(26) X(26) X(26) ST MARKS FL 34 X 24(24) 74(98) X(98) X(98) X(98) X(98) ST MARKS FL 50 X 2( 2) 62(64) X(64) X(64) X(64) X(64) ST MARKS FL 64 X X( X) 29(29) X(29) X(29) X(29) X(29) APALACHICOLA 34 X 53(53) 45(98) X(98) X(98) X(98) X(98) APALACHICOLA 50 X 9( 9) 80(89) X(89) X(89) X(89) X(89) APALACHICOLA 64 X 1( 1) 61(62) X(62) X(62) X(62) X(62) GFMX 290N 850W 34 3 74(77) 22(99) X(99) X(99) X(99) X(99) GFMX 290N 850W 50 X 27(27) 66(93) X(93) X(93) X(93) X(93) GFMX 290N 850W 64 X 6( 6) 65(71) X(71) X(71) X(71) X(71) PANAMA CITY FL 34 X 35(35) 55(90) X(90) X(90) X(90) X(90) PANAMA CITY FL 50 X 4( 4) 62(66) X(66) X(66) X(66) X(66) PANAMA CITY FL 64 X X( X) 31(31) X(31) X(31) X(31) X(31) DESTIN EXEC AP 34 X 9( 9) 38(47) X(47) X(47) X(47) X(47) DESTIN EXEC AP 50 X 1( 1) 8( 9) X( 9) X( 9) X( 9) X( 9) DESTIN EXEC AP 64 X X( X) 1( 1) 1( 2) X( 2) X( 2) X( 2) ALBANY GA 34 X 7( 7) 85(92) 1(93) X(93) X(93) X(93) ALBANY GA 50 X X( X) 45(45) 1(46) X(46) X(46) X(46) ALBANY GA 64 X X( X) 2( 2) 1( 3) X( 3) X( 3) X( 3) COLUMBUS GA 34 X 2( 2) 69(71) 8(79) X(79) X(79) X(79) COLUMBUS GA 50 X X( X) 10(10) 3(13) X(13) X(13) X(13) MACON GA 34 X 1( 1) 66(67) 8(75) X(75) X(75) X(75) MACON GA 50 X X( X) 6( 6) 4(10) X(10) X(10) X(10) DOTHAN AL 34 X 7( 7) 76(83) X(83) X(83) X(83) X(83) DOTHAN AL 50 X X( X) 37(37) X(37) X(37) X(37) X(37) DOTHAN AL 64 X X( X) 3( 3) 1( 4) X( 4) X( 4) X( 4) BIRMINGHAM AL 34 X X( X) 6( 6) 7(13) X(13) X(13) X(13) MONTGOMERY AL 34 X 2( 2) 22(24) 4(28) X(28) X(28) X(28) MONTGOMERY AL 50 X X( X) 2( 2) 1( 3) X( 3) X( 3) X( 3) WHITING FLD FL 34 X 7( 7) 14(21) X(21) X(21) X(21) X(21) WHITING FLD FL 50 X X( X) 3( 3) X( 3) X( 3) X( 3) X( 3) PENSACOLA FL 34 X 7( 7) 11(18) X(18) X(18) X(18) X(18) GFMX 290N 870W 34 3 32(35) 17(52) X(52) X(52) X(52) X(52) GFMX 290N 870W 50 X 5( 5) 7(12) X(12) X(12) X(12) X(12) GFMX 290N 870W 64 X X( X) 2( 2) X( 2) X( 2) X( 2) X( 2) MOBILE AL 34 X 4( 4) 3( 7) X( 7) X( 7) X( 7) X( 7) GULFPORT MS 34 X 4( 4) 2( 6) X( 6) X( 6) X( 6) X( 6) STENNIS MS 34 X 3( 3) 2( 5) X( 5) X( 5) X( 5) X( 5) BURAS LA 34 X 5( 5) 1( 6) X( 6) X( 6) X( 6) X( 6) GFMX 280N 890W 34 5 5(10) 2(12) X(12) X(12) X(12) X(12) NEW ORLEANS LA 34 X 1( 1) 2( 3) X( 3) X( 3) X( 3) X( 3) GFMX 280N 910W 34 X 2( 2) 1( 3) X( 3) X( 3) X( 3) X( 3) MERIDA MX 34 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) COZUMEL MX 34 99 X(99) X(99) X(99) X(99) X(99) X(99) CP SAN ANTONIO 34 99 X(99) X(99) X(99) X(99) X(99) X(99) CP SAN ANTONIO 50 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) HAVANA 34 28 6(34) X(34) X(34) X(34) X(34) X(34) ISLE OF PINES 34 99 X(99) X(99) X(99) X(99) X(99) X(99) $$ FORECASTER BERG

...HELENE MOVING INTO THE SOUTHEASTERN GULF OF MEXICO... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... As of 1:00 PM CDT Wed Sep 25 the center of Helene was located near 22.0, -86.4 with movement NNW at 10 mph. The minimum central pressure was 980 mb with maximum sustained winds of about 80 mph.

Issued at 100 PM CDT Wed Sep 25 2024 000 WTNT34 KNHC 251751 TCPAT4 BULLETIN Hurricane Helene Intermediate Advisory Number 9A NWS National Hurricane Center Miami FL AL092024 100 PM CDT Wed Sep 25 2024 ...HELENE MOVING INTO THE SOUTHEASTERN GULF OF MEXICO... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...22.0N 86.4W ABOUT 110 MI...175 KM NNE OF COZUMEL MEXICO ABOUT 480 MI...775 KM SSW OF TAMPA FLORIDA MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Indian Pass southward to Flamingo * Tampa Bay * Charlotte Harbor A Hurricane Warning is in effect for... * Anclote River to Mexico Beach * Cabo Catoche to Tulum, Mexico including Cozumel A Storm Surge Watch is in effect for... * West of Indian Pass to Mexico Beach A Hurricane Watch is in effect for... * Cuban province of Pinar del Rio * Englewood to Anclote River, including Tampa Bay A Tropical Storm Warning is in effect for... * Florida Keys, including the Dry Tortugas * Flamingo to Anclote River, including Tampa Bay * West of Mexico Beach to the Okaloosa/Walton County Line * Flamingo northward to South Santee River * Lake Okeechobee * Rio Lagartos to Cabo Catoche, Mexico * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth A Tropical Storm Watch is in effect for... * North of South Santee River to Little River Inlet A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within the next 36 hours. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area. Additional watches or warnings may be required later today or tonight. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 100 PM CDT (1800 UTC), the center of Hurricane Helene was located near latitude 22.0 North, longitude 86.4 West. Helene is moving toward the north-northwest near 10 mph (17 km/h). A turn toward the north and north-northeast with an increase in forward speed is expected later today through Thursday, bringing the center of Helene across the eastern Gulf of Mexico and to the Florida Big Bend coast by Thursday evening. After landfall, Helene is expected to slow down and turn toward the northwest over the southeastern United States Friday and Saturday. Data from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds remain near 80 mph (130 km/h) with higher gusts. Strengthening is forecast, and Helene is expected to be a major hurricane when it reaches the Florida Big Bend coast Thursday evening. Weakening is expected after landfall, but Helene's fast forward speed will allow strong, damaging winds, especially in gusts, to penetrate well inland across the southeastern United States, including over the higher terrain of the southern Appalachians. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 275 miles (445 km). A commercial fishing vessel located near Isla Mujeres, Mexico, recently reported a wind of 63 mph (102 km/h). Dropsonde data indicate that the minimum central pressure has been relatively steady during the past few hours and is estimated to be 980 mb (28.94 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for Helene can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC and on the web at hurricanes.gov/text/MIATCDAT4.shtml STORM SURGE: The combination of a life-threatening storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Carrabelle, FL to Chassahowitzka, FL...12-18 ft Apalachicola, FL to Carrabelle, FL...8-12 ft Chassahowitzka, FL to Anclote River, FL...8-12 ft Indian Pass, FL to Apalachicola, FL...6-9 ft Anclote River, FL to Middle of Longboat Key, FL...5-8 ft Tampa Bay...5-8 ft Middle of Longboat Key, FL to Englewood, FL...4-7 ft Englewood, FL to Flamingo, FL...3-5 ft Charlotte Harbor...3-5 ft For a complete depiction of areas at risk of storm surge inundation, please see the National Weather Service Peak Storm Surge Graphic, available at hurricanes.gov/graphics_at4.shtml?peakSurge. Storm surge could raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore winds along the southern coast of Pinar del Rio, Cuba, including the Isle of Youth. Storm surge could raise water levels by as much as 3 to 5 feet above ground level in areas of onshore winds within the warning area along the north coast of the Yucatan Peninsula. WIND: Hurricane conditions are expected within the U.S. hurricane warning area late Thursday, with tropical storm conditions beginning Thursday morning. Tropical storm conditions are expected in southern Florida later today and will spread northward across the rest of Florida, Georgia, and South Carolina through Thursday. Tropical storm conditions are possible within the tropical storm watch area in South Carolina beginning on Thursday. Hurricane conditions, especially in gusts, are expected in the hurricane warning area in Mexico during the next several hours. Tropical storm conditions are occurring in the warning area in Cuba, and hurricane conditions are possible for the western portion of Cuba today. RAINFALL: Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba, the Cayman Islands, and the northeast Yucatan Peninsula, with isolated totals around 12 inches. This rainfall brings a risk of considerable flooding. A 24-hour rainfall total of 8.60 inches (218.4 mm) was recently reported in Embalse Herradura, Pinar del Rio, Cuba, by the Meteorological Service of Cuba. Over the Southeastern U.S. into the Southern Appalachians, Helene is expected to produce total rain accumulations of 5 to 10 inches with isolated totals around 15 inches. This rainfall will likely result in areas of considerable flash and urban flooding, with areas of significant river flooding. Landslides are possible in areas of steep terrain in the southern Appalachians. For a complete depiction of forecast rainfall associated with Helene, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero. TORNADOES: A tornado or two may occur tonight over parts of the Florida Peninsula and southern Alabama. The risk of tornadoes will increase on Thursday, expanding northward across Florida into parts of Georgia and South Carolina. SURF: Swells generated by Helene will affect the southern coast of Cuba and the Yucatan Peninsula of Mexico during the next couple of days. Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast later today and Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next complete advisory at 400 PM CDT. $$ Forecaster Berg

5-Day Uncertainty Track last updated Wed, 25 Sep 2024 17:51:54 GMT


Wind Speed Probabilities last updated Wed, 25 Sep 2024 15:22:59 GMT

000
ABNT20 KNHC 251745
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Wed Sep 25 2024

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

Active Systems:
The National Hurricane Center is issuing advisories on recently
upgraded Hurricane Helene, located over the southeastern Gulf of
Mexico.

Eastern and Central Tropical Atlantic (AL98):
A broad low pressure system associated with a tropical wave located
west of the Cabo Verde Islands continues to produce disorganized
shower and thunderstorm activity. Environmental conditions appear
favorable for gradual development of this system, and a tropical
depression is likely to form in a few days while it moves westward
to west-northwestward across the eastern and central tropical
Atlantic.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...80 percent.

Central Subtropical Atlantic (AL99):
A non-tropical area of low pressure is currently located several
hundred miles to the northeast of Bermuda. The system is currently
producing winds up to storm force, and environmental conditions
could support the low developing some subtropical or tropical
characteristics over the next several days as the system moves
generally east-northeastward, remaining over the central Subtropical
Atlantic. Additional information on this system, including storm
warnings, can be found in High Seas Forecasts issued by the National
Weather Service.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...20 percent.

&&
High Seas Forecasts issued by the National Weather Service
can be found under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

$$
Forecaster Kelly

Potential Storm Surge Flooding Map last updated Wed, 25 Sep 2024 16:25:07 GMT

Probabilistic Storm Surge Graphics last updated Wed, 25 Sep 2024 15:29:34 GMT

5-Day Uncertainty Track last updated Wed, 25 Sep 2024 14:59:40 GMT


Wind Speed Probabilities last updated Wed, 25 Sep 2024 14:59:40 GMT

Storm Surge Watch/Warning Map last updated Wed, 25 Sep 2024 14:58:12 GMT

Issued at 1000 AM CDT Wed Sep 25 2024 000 WTNT44 KNHC 251457 TCDAT4 Hurricane Helene Discussion Number 9 NWS National Hurricane Center Miami FL AL092024 1000 AM CDT Wed Sep 25 2024 Air Force Reserve and NOAA Hurricane Hunter aircraft have been investigating Helene, with each plane recently measuring peak flight-level winds of 81 kt and 78 kt, respectively. Helene has therefore become a hurricane with an estimated intensity of 70 kt. Dropsonde data also indicate that the pressure has fallen to about 979 mb. Radar data from Mexico and Cuba, as well as reconnaissance reports, indicate that Helene has formed a partial, elliptical eyewall that is open on the east side. Helene has turned north-northwestward (330/9 kt) and is expected to turn northward and north-northeastward later today and tonight, bringing the center to the coast of the Florida Big Bend Thursday evening. After landfall, Helene is expected to interact with a deep-layer trough over the Lower Mississippi Valley and swing back to the northwest and stall near the Tennessee Valley late Friday into the weekend. The track guidance remains tightly clustered, and the NHC forecast is generally just an update of the previous prediction. It is still too soon at this point to be overly focused on an exact landfall location and time, since NHC track forecasts can be off by an average of 60 nm at the 36-hour forecast time. Helene is expected to move through/over an environment of relatively low shear, strong upper-level divergence, and sea surface temperatures of 29-31 degrees Celsius, all of which should foster additional strengthening. Rapid Intensification (RI) indices indicate a high chance of RI during the next 24 hours, and as a result the NHC intensity forecast shows Helene becoming a major hurricane by Thursday morning. There is still some uncertainty on exactly how strong Helene will get, and upward adjustments to the forecast intensity could be required in subsequent advisories if Helene rapidly intensifies more than forecast. Regardless, Helene is forecast to be a large major hurricane when it reaches the Big Bend coast of Florida. As a result, storm surge, wind, and rainfall impacts will likely extend well away from the center and outside the forecast cone, particularly on the east side. In addition, the fast forward speed while Helene crosses the coast will likely result in farther inland penetration of strong winds over parts of the southeastern United States after landfall, including strong gusts over higher terrain of the southern Appalachians. KEY MESSAGES: 1. Hurricane and tropical storm conditions are expected over northeastern portions of the Yucatan Peninsula of Mexico today where Tropical Storm and Hurricane Warnings are in effect. Tropical storm conditions are occurring over portions of western Cuba within the Tropical Storm Warning area, and hurricane conditions are possible today within the Hurricane Watch area. 2. Due to the large size of Helene, there is a danger of life-threatening storm surge along the entire west coast of the Florida Peninsula and Florida Big Bend. The highest inundation of greater than 10 ft is expected along the Florida Big Bend coast. Residents in those areas should follow advice given by local officials and evacuate if told to do so. 3. Devastating hurricane-force winds are expected across portions of northern Florida and southern Georgia where the core of Helene moves inland. Preparations to protect life and property should be completed by early Thursday since tropical storm conditions are expected to begin within these areas on Thursday. Because of Helene’s expected fast forward speed, damaging and life-threatening wind gusts, are expected to penetrate well inland over portions of the southeastern United States, including in the higher terrain of the southern Appalachians. 4. Helene will bring heavy rain to portions of the western Caribbean with potentially significant flooding across western Cuba and the northeastern Yucatan Peninsula into early Thursday. Considerable and potentially life-threatening flash and urban flooding is expected across portions of northwestern and northern Florida, the Southeast, southern Appalachians, and the Upper Tennessee Valley Wednesday through Friday. This includes the risk of landslides across the southern Appalachians. Widespread minor to moderate river flooding is likely, and isolated major river flooding is possible. FORECAST POSITIONS AND MAX WINDS INIT 25/1500Z 21.6N 86.3W 70 KT 80 MPH 12H 26/0000Z 23.0N 86.4W 85 KT 100 MPH 24H 26/1200Z 25.7N 85.7W 105 KT 120 MPH 36H 27/0000Z 29.7N 84.6W 110 KT 125 MPH 48H 27/1200Z 34.3N 85.0W 50 KT 60 MPH...INLAND 60H 28/0000Z 36.6N 86.9W 30 KT 35 MPH...POST-TROP/INLAND 72H 28/1200Z 36.9N 87.8W 20 KT 25 MPH...POST-TROP/INLAND 96H 29/1200Z 36.6N 87.9W 15 KT 15 MPH...POST-TROP/INLAND 120H 30/1200Z...DISSIPATED $$ Forecaster Berg

...HELENE BECOMES A HURRICANE... ...EXPECTED TO BRING LIFE-THREATENING STORM SURGE, DAMAGING WINDS, AND FLOODING RAINS TO A LARGE PORTION OF FLORIDA AND THE SOUTHEASTERN UNITED STATES... As of 10:00 AM CDT Wed Sep 25 the center of Helene was located near 21.6, -86.3 with movement NNW at 10 mph. The minimum central pressure was 979 mb with maximum sustained winds of about 80 mph.