Issued at 900 PM EDT Thu Sep 26 2024 000 WTNT64 KNHC 270056 TCUAT4 Hurricane Helene Tropical Cyclone Update NWS National Hurricane Center Miami FL AL092024 900 PM EDT Thu Sep 26 2024 ...HELENE SLIGHTLY STRONGER AS ITS EYE APPROACHES THE COAST OF THE FLORIDA BIG BEND... ...900 PM EDT POSITION UPDATE... A University of Florida Coastal Monitoring Program tower located on Cedar Key recently reported a sustained wind of 55 mph (89 km/h) and a wind gust of 73 mph (117 km/h). A NOAA National Ocean Service tide gauge located at Clearwater Beach recently reported a water level of 5.07 feet above mean higher high water, which is an approximation of inundation in that area. SUMMARY OF 900 PM EDT...0100 UTC...INFORMATION ---------------------------------------------- LOCATION...29.1N 84.2W ABOUT 65 MI...105 KM W OF CEDAR KEY FLORIDA ABOUT 90 MI...145 KM S OF TALLAHASSEE FLORIDA MAXIMUM SUSTAINED WINDS...140 MPH...225 KM/H PRESENT MOVEMENT...NNE OR 20 DEGREES AT 24 MPH...39 KM/H MINIMUM CENTRAL PRESSURE...941 MB...27.79 INCHES $$ Forecaster Bucci/Sardi

Issued at 800 PM EDT Thu Sep 26 2024 000 WTNT34 KNHC 262353 TCPAT4 BULLETIN Hurricane Helene Intermediate Advisory Number 14A NWS National Hurricane Center Miami FL AL092024 800 PM EDT Thu Sep 26 2024 ...EXTREMELY DANGEROUS HURRICANE HELENE NEARING THE NORTHEAST GULF COAST... ...CATASTROPHIC STORM SURGE AND LIFE-THREATENING WINDS EXPECTED IN THE FLORIDA BIG BEND AREA... SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION ---------------------------------------------- LOCATION...28.7N 84.3W ABOUT 80 MI...125 KM WSW OF CEDAR KEY FLORIDA ABOUT 115 MI...190 KM S OF TALLAHASSEE FLORIDA MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H PRESENT MOVEMENT...NNE OR 25 DEGREES AT 23 MPH...37 KM/H MINIMUM CENTRAL PRESSURE...942 MB...27.82 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None 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 A Hurricane Watch is in effect for... * 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 A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline. 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 Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Hurricane Watch means that hurricane conditions are possible within the watch area. 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. DISCUSSION AND OUTLOOK ---------------------- At 800 PM EDT (0000 UTC), the eye of Hurricane Helene was located near latitude 28.7 North, longitude 84.3 West. Helene is moving toward the north-northeast near 23 mph (37 km/h). A continued fast motion to the north-northeast is expected through landfall in the Florida Big Bend in a few hours. After landfall, Helene is expected to turn northwestward and slow down over the Tennessee Valley on Friday and Saturday. Maximum sustained winds are near 130 mph (215 km/h) with higher gusts. Helene is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some additional strengthening is possible before the center reaches the coast in a few hours. Weakening is expected after Helene moves inland, but the 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 60 miles (95 km) from the center and tropical-storm-force winds extend outward up to 310 miles (500 km). Albert Whitted airport in St. Petersburg, Florida reported a sustained wind of 53 mph (85 km/h) with a gust to 76 mph (122 km/h). The minimum central pressure estimated from Hurricane Hunter aircraft observations is 942 mb (27.82 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 The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. 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. WIND: Hurricane conditions are beginning within the hurricane warning area. When the eye comes ashore, people are reminded to not venture out into the relative calm, as hazardous winds will increase very quickly when the eye passes. Tropical storm conditions are occurring in southern and central Florida, and these conditions will be spreading northward across the tropical storm warning areas in the Southeastern U.S. through early Friday. Strong, damaging winds, especially in gusts, will likely penetrate as far inland as the higher terrain of the southern Appalachians. RAINFALL: 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 20 inches. This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Numerous significant landslides are expected 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. For a list of rainfall observations (and wind reports) associated this storm, see the companion storm summary at WBCSCCNS4 with the WMO header ACUS44 KWBC or at the following link: www.wpc.ncep.noaa.gov/discussions/nfdscc4.html. TORNADOES: The risk for several tornadoes continues through tonight over much of Florida, southeast Georgia, central and southern South Carolina, and southern North Carolina. The tornado risk will continue Friday across the Carolinas and southern Virginia. SURF: Swells generated by Helene will affect much of Florida and the coasts of Georgia and the Carolinas during the next couple of days. 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 1100 PM EDT. $$ Forecaster Pasch

000
ABNT20 KNHC 262306
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Thu Sep 26 2024

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

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Helene, located over the northeastern Gulf of Mexico and on
Tropical Storm Isaac, located over the central Subtropical Atlantic
Ocean.

Eastern and Central Tropical Atlantic (AL98):
Showers and thunderstorms associated with an area of low pressure
located about one thousand miles west of the Cabo Verde Islands
continue to show signs of organization. Recent satellite imagery
suggests the system does not yet have a well-defined surface
circulation. However, environmental conditions are expected to be
conducive for further development. A tropical depression is
expected to form tonight or on Friday while the disturbance moves
generally westward to west-northwestward at 10 to 15 mph. The
system is then forecast to slow down and turn north-northwestward
late Friday and Saturday.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

Western Caribbean:
An area of low pressure could form over the western Caribbean Sea
by the middle of next week. Environmental conditions are expected to
be conducive for slow development thereafter, while the system
moves generally northwestward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.

&&
Public Advisories on Tropical Storm Isaac are issued under WMO
header WTNT35 KNHC and under AWIPS header MIATCPAT5.
Forecast/Advisories on Tropical Storm Isaac are issued under WMO
header WTNT25 KNHC and under AWIPS header MIATCMAT5.

$$
Forecaster Hagen

...EXTREMELY DANGEROUS CATEGORY 4 HELENE HEADING TOWARDS THE FLORIDA BIG BEND... ...700 PM EDT POSITION UPDATE... As of 7:00 PM EDT Thu Sep 26 the center of Helene was located near 28.3, -84.4 with movement NNE at 23 mph. The minimum central pressure was 945 mb with maximum sustained winds of about 130 mph.

Issued at 700 PM EDT Thu Sep 26 2024 000 WTNT64 KNHC 262259 TCUAT4 Hurricane Helene Tropical Cyclone Update NWS National Hurricane Center Miami FL AL092024 700 PM EDT Thu Sep 26 2024 ...EXTREMELY DANGEROUS CATEGORY 4 HELENE HEADING TOWARDS THE FLORIDA BIG BEND... ...700 PM EDT POSITION UPDATE... A Weatherflow station at Egmont Channel near the entrance of Tampa Bay recently reported a sustained wind of 54 mph (87 km/h) and a wind gust of 71 mph (115 km/h). Tropical storm conditions are approaching the coastline of Florida's Big Bend. A Weatherflow station at St. George Island recently reported a wind gust of 46 mph (74 km/h). SUMMARY OF 700 PM EDT...2300 UTC...INFORMATION ---------------------------------------------- LOCATION...28.3N 84.4W ABOUT 110 MI...175 KM W OF TAMPA FLORIDA ABOUT 145 MI...235 KM S OF TALLAHASSEE FLORIDA MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H PRESENT MOVEMENT...NNE OR 25 DEGREES AT 23 MPH...37 KM/H MINIMUM CENTRAL PRESSURE...945 MB...27.91 INCHES $$ Forecaster Bucci

...HELENE NOW AN EXTREMELY DANGEROUS CATEGORY 4 HURRICANE... As of 6:20 PM EDT Thu Sep 26 the center of Helene was located near 28.0, -84.5 with movement NNE at 23 mph. The minimum central pressure was 947 mb with maximum sustained winds of about 130 mph.

Issued at 620 PM EDT Thu Sep 26 2024 000 WTNT64 KNHC 262218 TCUAT4 Hurricane Helene Tropical Cyclone Update NWS National Hurricane Center Miami FL AL092024 620 PM EDT Thu Sep 26 2024 ...HELENE NOW AN EXTREMELY DANGEROUS CATEGORY 4 HURRICANE... A NOAA Hurricane Hunter aircraft currently investigating Helene recently found that the maximum sustained winds have increased to 130 mph (215 km/h). The minimum central pressure has also decreased to 947 mb (27.96 inches) based on dropsonde data. SUMMARY OF 620 PM EDT...2220 UTC...INFORMATION ---------------------------------------------- LOCATION...28.0N 84.5W ABOUT 120 MI...195 KM W OF TAMPA FLORIDA ABOUT 165 MI...265 KM S OF TALLAHASSEE FLORIDA MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H PRESENT MOVEMENT...NNE OR 25 DEGREES AT 23 MPH...37 KM/H MINIMUM CENTRAL PRESSURE...947 MB...27.96 INCHES $$ Forecaster Bucci/Pasch

Potential Storm Surge Flooding Map last updated Thu, 26 Sep 2024 21:37:54 GMT

Issued at 2100 UTC THU SEP 26 2024 613 FONT14 KNHC 262042 PWSAT4 HURRICANE HELENE WIND SPEED PROBABILITIES NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 2100 UTC THU SEP 26 2024 AT 2100Z THE CENTER OF HURRICANE HELENE WAS LOCATED NEAR LATITUDE 27.9 NORTH...LONGITUDE 84.6 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 110 KTS...125 MPH...205 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 THU 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 THU 06Z FRI 18Z FRI 06Z SAT 18Z SAT 18Z SUN 18Z MON PERIODS TO TO TO TO TO TO TO 06Z FRI 18Z FRI 06Z SAT 18Z SAT 18Z SUN 18Z MON 18Z TUE FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT GREENSBORO NC 34 X 3( 3) X( 3) X( 3) X( 3) X( 3) X( 3) CHARLOTTE NC 34 3 6( 9) X( 9) X( 9) X( 9) X( 9) X( 9) FLORENCE SC 34 4 3( 7) X( 7) X( 7) X( 7) X( 7) X( 7) COLUMBIA SC 34 11 22(33) X(33) X(33) X(33) X(33) X(33) LITTLE RIVER 34 4 6(10) X(10) X(10) X(10) X(10) X(10) MYRTLE BEACH 34 8 8(16) X(16) X(16) X(16) X(16) X(16) GEORGETOWN SC 34 5 1( 6) X( 6) X( 6) X( 6) X( 6) X( 6) CHARLESTON SC 34 45 8(53) X(53) X(53) X(53) X(53) X(53) BEAUFORT MCAS 34 76 3(79) X(79) X(79) X(79) X(79) X(79) ATLANTA GA 34 16 81(97) X(97) X(97) X(97) X(97) X(97) ATLANTA GA 50 X 11(11) X(11) X(11) X(11) X(11) X(11) AUGUSTA GA 34 75 18(93) X(93) X(93) X(93) X(93) X(93) SAVANNAH GA 34 90 1(91) X(91) X(91) X(91) X(91) X(91) KINGS BAY GA 34 95 1(96) X(96) X(96) X(96) X(96) X(96) KINGS BAY GA 50 8 X( 8) X( 8) X( 8) X( 8) X( 8) X( 8) WAYCROSS GA 34 99 X(99) X(99) X(99) X(99) X(99) X(99) WAYCROSS GA 50 41 X(41) X(41) X(41) X(41) X(41) X(41) WAYCROSS GA 64 2 1( 3) X( 3) X( 3) X( 3) X( 3) X( 3) MAYPORT NS FL 34 93 X(93) X(93) X(93) X(93) X(93) X(93) MAYPORT NS FL 50 5 X( 5) X( 5) X( 5) X( 5) X( 5) X( 5) JACKSONVILLE 34 99 X(99) X(99) X(99) X(99) X(99) X(99) JACKSONVILLE 50 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) GAINESVILLE FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) GAINESVILLE FL 50 11 X(11) X(11) X(11) X(11) X(11) X(11) DAYTONA BEACH 34 92 X(92) X(92) X(92) X(92) X(92) X(92) THE VILLAGES 34 99 X(99) X(99) X(99) X(99) X(99) X(99) ORLANDO FL 34 98 X(98) X(98) X(98) X(98) X(98) X(98) COCOA BEACH FL 34 70 X(70) X(70) X(70) X(70) X(70) X(70) PATRICK AFB 34 72 X(72) X(72) X(72) X(72) X(72) X(72) FT PIERCE FL 34 29 X(29) X(29) X(29) X(29) X(29) X(29) W PALM BEACH 34 7 X( 7) X( 7) X( 7) X( 7) X( 7) X( 7) FT LAUDERDALE 34 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) KEY WEST FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) NAPLES FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) FT MYERS FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) VENICE FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) TAMPA FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) TAMPA FL 50 3 X( 3) X( 3) X( 3) X( 3) X( 3) X( 3) CEDAR KEY FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) CEDAR KEY FL 50 85 X(85) X(85) X(85) X(85) X(85) X(85) CEDAR KEY FL 64 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) TALLAHASSEE FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) TALLAHASSEE FL 50 91 X(91) X(91) X(91) X(91) X(91) X(91) TALLAHASSEE FL 64 31 X(31) X(31) X(31) X(31) X(31) X(31) ST MARKS FL 34 99 X(99) X(99) X(99) X(99) X(99) X(99) ST MARKS FL 50 97 X(97) X(97) X(97) X(97) X(97) X(97) ST MARKS FL 64 50 X(50) X(50) X(50) X(50) X(50) X(50) APALACHICOLA 34 99 X(99) X(99) X(99) X(99) X(99) X(99) APALACHICOLA 50 55 X(55) X(55) X(55) X(55) X(55) X(55) APALACHICOLA 64 16 X(16) X(16) X(16) X(16) X(16) X(16) GFMX 290N 850W 34 99 X(99) X(99) X(99) X(99) X(99) X(99) GFMX 290N 850W 50 82 X(82) X(82) X(82) X(82) X(82) X(82) GFMX 290N 850W 64 34 X(34) X(34) X(34) X(34) X(34) X(34) PANAMA CITY FL 34 85 X(85) X(85) X(85) X(85) X(85) X(85) PANAMA CITY FL 50 3 X( 3) X( 3) X( 3) X( 3) X( 3) X( 3) DESTIN EXEC AP 34 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) ALBANY GA 34 99 1(99) X(99) X(99) X(99) X(99) X(99) ALBANY GA 50 75 5(80) X(80) X(80) X(80) X(80) X(80) ALBANY GA 64 9 1(10) X(10) X(10) X(10) X(10) X(10) COLUMBUS GA 34 51 30(81) X(81) X(81) X(81) X(81) X(81) COLUMBUS GA 50 1 11(12) X(12) X(12) X(12) X(12) X(12) MACON GA 34 95 5(99) X(99) X(99) X(99) X(99) X(99) MACON GA 50 5 79(84) X(84) X(84) X(84) X(84) X(84) DOTHAN AL 34 64 X(64) X(64) X(64) X(64) X(64) X(64) BIRMINGHAM AL 34 2 1( 3) X( 3) X( 3) X( 3) X( 3) X( 3) MONTGOMERY AL 34 4 1( 5) X( 5) X( 5) X( 5) X( 5) X( 5) GFMX 290N 870W 34 4 X( 4) X( 4) X( 4) X( 4) X( 4) X( 4) $$ FORECASTER CANGIALOSI

Probabilistic Storm Surge Graphics last updated Thu, 26 Sep 2024 21:16:01 GMT

Issued at 500 PM EDT Thu Sep 26 2024 076 WTNT44 KNHC 262043 TCDAT4 Hurricane Helene Discussion Number 14 NWS National Hurricane Center Miami FL AL092024 500 PM EDT Thu Sep 26 2024 Helene has rapidly intensified today while nearing landfall in the Florida Big Bend. Doppler radar and aircraft data indicate that the eyewall is now completely closed and the eye has become more circular and is clearing out. The aircraft data also indicated that the inner core has contracted significantly today while the tropical-storm-force winds have expanded. Based on all of the data, the initial intensity is set at 110 kt. The latest minimum pressure based on the aircraft data is around 951 mb. Tropical-storm-force winds are occurring across portions of west-central and southwestern Florida, and conditions are expected to deteriorate rapidly in the hurricane warning area during the next several hours. It should be emphasized that Helene is at the upper bound of hurricanes in terms of storm size and impacts are and will occur well away from the center. The large hurricane is now accelerating north-northeastward, with the latest initial motion estimated to be 025/20 kt. This general motion is expected to continue, taking the core of the major hurricane to the Florida Big Bend later this evening. After landfall, a turn to the north over Georgia is expected late tonight and early Friday, followed by a slowdown or a complete stall over the Tennessee Valley late Friday and Saturday when Helene merges with a mid- to upper-level low. The hurricane has intensified by 30 kt since sunrise and given the conducive environmental conditions and contracting inner core, it seems likely that Helene will be at or very near category 4 strength when it makes landfall in the Florida Big Bend this evening. 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 the higher terrain of the southern Appalachians. Accordingly, a higher-than-normal gust factor is indicated in the official forecast while Helene is inland. KEY MESSAGES: 1. A catastrophic and deadly storm surge will occur along portions of the Florida Big Bend coast, where inundation could reach as high as 20 feet above ground level, along with destructive waves. If you live in this area and were told to evacuate by local officials, your opportunity to do so is almost over. There is also a danger of life-threatening storm surge along the remainder of the west coast of the Florida Peninsula. 2. Potentially catastrophic hurricane-force winds are expected within the eyewall of Helene and will spread inland over portions of northern Florida and southern Georgia when Helene makes landfall in the Florida Big Bend region this evening. Persons in these areas should be prepared to take shelter in the interior portion of a well-built structure and remain sheltered until after hazardous conditions pass. You may need to remain sheltered after the storm due to downed trees and power lines, as well as flooding, in the area. 3. Damaging wind gusts will penetrate well inland over portions of Georgia and the Carolinas tonight, particularly over the higher terrain of the southern Appalachians. Residents in these areas should be prepared for the possibility of long-duration power outages. If you use a generator after the storm, be sure it is placed outside at least 20 feet away from doors, windows, and garages to avoid deadly carbon monoxide poisoning. 4. Catastrophic and life-threatening flash and urban flooding, including numerous significant 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 significant river flooding and isolated major river flooding are likely. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 27.9N 84.6W 110 KT 125 MPH 12H 27/0600Z 31.5N 83.7W 90 KT 105 MPH...INLAND 24H 27/1800Z 35.8N 85.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 28/0600Z 37.0N 86.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 28/1800Z 37.1N 87.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 60H 29/0600Z 37.1N 87.3W 20 KT 25 MPH...POST-TROP/EXTRATROP 72H 29/1800Z...DISSIPATED $$ Forecaster Cangialosi

Issued at 500 PM EDT Thu Sep 26 2024 618 WTNT34 KNHC 262042 TCPAT4 BULLETIN Hurricane Helene Advisory Number 14 NWS National Hurricane Center Miami FL AL092024 500 PM EDT Thu Sep 26 2024 ...HELENE IS A VERY DANGEROUS AND LARGE MAJOR HURRICANE... ...DAMAGING HURRICANE WINDS AND CATASTROPHIC STORM SURGE EXPECTED TO BEGIN IN THE FLORIDA BIG BEND THIS EVENING... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...27.9N 84.6W ABOUT 130 MI...205 KM W OF TAMPA FLORIDA ABOUT 175 MI...280 KM S OF TALLAHASSEE FLORIDA MAXIMUM SUSTAINED WINDS...125 MPH...205 KM/H PRESENT MOVEMENT...NNE OR 25 DEGREES AT 23 MPH...37 KM/H MINIMUM CENTRAL PRESSURE...951 MB...28.09 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None 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 A Hurricane Watch is in effect for... * 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 A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline. 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. 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. A Hurricane Watch means that hurricane conditions are possible within the watch area. 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 500 PM EDT (2100 UTC), the eye of Hurricane Helene was located near latitude 27.9 North, longitude 84.6 West. Helene is moving toward the north-northeast near 23 mph (37 km/h). A continued fast motion to the north-northeast is expected through landfall in the Florida Big Bend this evening. After landfall, Helene is expected to turn northwestward and slow down over the Tennessee Valley on Friday and Saturday. Maximum sustained winds have increased to near 125 mph (205 km/h) with higher gusts. Helene is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Additional strengthening is expected, and Helene will likely be an extremely dangerous category 4 hurricane at landfall. Weakening is expected after Helene moves inland, but the 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 60 miles (95 km) from the center and tropical-storm-force winds extend outward up to 310 miles (500 km). A weather station at Venice Municipal Airport recently reported a sustained wind of 46 mph (74 km/h) with a gust of 69 mph (111 km/h). Another observation near Venice Beach reported a sustained wind of 51 mph (82 km/h) with a gust to 66 mph (106 km/h). The estimated minimum central pressure based on data from the Air Force Hurricane Hunters is 951 mb (28.09 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 The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. 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. WIND: Hurricane conditions are expected within the hurricane warning area this evening. Tropical storm conditions are occurring in the southern and central Florida, and these conditions are expected to spread northward across the tropical storm warning areas in the Southeastern U.S. through early Friday. Strong, damaging winds, especially in gusts, will likely penetrate as far inland as the higher terrain of the southern Appalachians. RAINFALL: 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 20 inches. This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Numerous significant landslides are expected 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. For a list of rainfall observations (and wind reports) associated this storm, see the companion storm summary at WBCSCCNS4 with the WMO header ACUS44 KWBC or at the following link: www.wpc.ncep.noaa.gov/discussions/nfdscc4.html. TORNADOES: The risk for several tornadoes continues through tonight over much of Florida, southeast Georgia, central and southern South Carolina, and southern North Carolina. The tornado risk will continue Friday across the Carolinas and southern Virginia. SURF: Swells generated by Helene will affect much of Florida and the coasts of Georgia and the Carolinas during the next couple of days. 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 800 PM EDT. Next complete advisory at 1100 PM EDT. $$ Forecaster Cangialosi

5-Day Uncertainty Track last updated Thu, 26 Sep 2024 20:54:33 GMT


Wind Speed Probabilities last updated Thu, 26 Sep 2024 21:31:28 GMT

Issued at 500 PM AST Thu Sep 26 2024 000 WTNT45 KNHC 262052 TCDAT5 Tropical Storm Isaac Discussion Number 4 NWS National Hurricane Center Miami FL AL102024 500 PM AST Thu Sep 26 2024 Little change with the structure of Isaac has been noted this afternoon. Episodic bursts of deep convection have been observed over the western semi-circle throughout the day, but cloud tops have largely failed to break -60C. There remains a relative void of thunderstorms over the eastern half of Isaac's circulation as it traverses across 26C water. ASCAT passes, combined with a blend of subjective Dvorak estimates from TAFB and SAB, plus objective estimates from UW-CIMSS collectively support maintaining an initial intensity of 45 kt for this advisory. For the next couple of days, the track guidance is tightly clustered as Isaac continues on a general east to east-northeast heading, remaining embedded within a well established mid-latitude trough. Beyond Saturday, there has been a large change in the dynamic model suite. A vast majority of the the guidance, including the deterministic ECMWF and several of its ensemble members, have shown a rather dramatic poleward shift, similar to previous runs of the GFS. This is ultimately induced by a slight decrease in forward speed, which in turn allows Isaac to be steered by a strong closed mid-latitude trough digging out of eastern Canada into the north Atlantic. This would force Isaac to the northeast and eventually northward. Isaac's medium range track confidence is quite low, owing to lack of model consistency during the past several runs. To avoid making too large of a change, the forecast track after Day 3 has shifted to the left for this advisory. However, it falls well to the east of the guidance envelope and further large changes may be needed. Despite the longer range track uncertainty, Isaac appears to be in an environment that should be generally conducive for some strengthening, especially during the next day or two. After that, unusually cold upper-tropospheric temperatures should help sustain the tropical cyclone for a while, even as it moves over colder SSTs in the 24-25 deg C range. By the end of the forecast period, much colder SSTs and a dramatic increase in shear should cause Isaac to become post-tropical. This transition could occur more quickly than forecast if the system takes a more northerly turn early next week. No changes of note were made to the official intensity forecast, which still shows Isaac reaching hurricane strength during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 37.5N 50.6W 45 KT 50 MPH 12H 27/0600Z 37.6N 48.7W 50 KT 60 MPH 24H 27/1800Z 38.2N 45.5W 60 KT 70 MPH 36H 28/0600Z 39.2N 42.0W 65 KT 75 MPH 48H 28/1800Z 40.5N 38.7W 65 KT 75 MPH 60H 29/0600Z 41.9N 35.9W 60 KT 70 MPH 72H 29/1800Z 43.0N 33.8W 60 KT 70 MPH 96H 30/1800Z 44.2N 27.8W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 01/1800Z 45.5N 22.5W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster D. Zelinsky/Bookbinder

Issued at 2100 UTC THU SEP 26 2024 000 FONT15 KNHC 262051 PWSAT5 TROPICAL STORM ISAAC WIND SPEED PROBABILITIES NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102024 2100 UTC THU SEP 26 2024 AT 2100Z THE CENTER OF TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE 37.5 NORTH...LONGITUDE 50.6 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 45 KTS...50 MPH...85 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 THU 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 THU 06Z FRI 18Z FRI 06Z SAT 18Z SAT 18Z SUN 18Z MON PERIODS TO TO TO TO TO TO TO 06Z FRI 18Z FRI 06Z SAT 18Z SAT 18Z SUN 18Z MON 18Z TUE FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT SANTA CRUZ AZO 34 X X( X) X( X) 1( 1) 11(12) 3(15) X(15) $$ FORECASTER D. ZELINSKY

...ISAAC CONTINUING EASTWARD WITH NO CHANGE IN STRENGTH... As of 5:00 PM AST Thu Sep 26 the center of Isaac was located near 37.5, -50.6 with movement E at 10 mph. The minimum central pressure was 995 mb with maximum sustained winds of about 50 mph.

Issued at 500 PM AST Thu Sep 26 2024 231 WTNT35 KNHC 262051 TCPAT5 BULLETIN Tropical Storm Isaac Advisory Number 4 NWS National Hurricane Center Miami FL AL102024 500 PM AST Thu Sep 26 2024 ...ISAAC CONTINUING EASTWARD WITH NO CHANGE IN STRENGTH... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...37.5N 50.6W ABOUT 1285 MI...2070 KM W OF THE AZORES ABOUT 880 MI...1415 KM ENE OF BERMUDA MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H PRESENT MOVEMENT...E OR 80 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 500 PM AST (2100 UTC), the center of Tropical Storm Isaac was located near latitude 37.5 North, longitude 50.6 West. Isaac is moving toward the east near 10 mph (17 km/h), and a turn toward the east-northeast is expected by the weekend. Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Strengthening is forecast, and Isaac is expected reach or be near hurricane strength by late Friday or early Saturday. Tropical-storm-force winds extend outward up to 60 miles (95 km) from the center. The estimated minimum central pressure is 995 mb (29.39 inches). HAZARDS AFFECTING LAND ---------------------- SURF: Swells generated by Isaac and a large wind fetch from a deep-layer trough are affecting portions of the coast of Bermuda and could spread into the Azores by this weekend. 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 1100 PM AST. $$ Forecaster D. Zelinsky/Bookbinder

Issued at 2100 UTC THU SEP 26 2024 000 WTNT25 KNHC 262050 TCMAT5 TROPICAL STORM ISAAC FORECAST/ADVISORY NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102024 2100 UTC THU SEP 26 2024 TROPICAL STORM CENTER LOCATED NEAR 37.5N 50.6W AT 26/2100Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE EAST OR 80 DEGREES AT 9 KT ESTIMATED MINIMUM CENTRAL PRESSURE 995 MB MAX SUSTAINED WINDS 45 KT WITH GUSTS TO 55 KT. 34 KT....... 30NE 40SE 50SW 40NW. 12 FT SEAS.. 60NE 120SE 180SW 210NW. 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 37.5N 50.6W AT 26/2100Z AT 26/1800Z CENTER WAS LOCATED NEAR 37.4N 51.2W FORECAST VALID 27/0600Z 37.6N 48.7W MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 0NE 30SE 0SW 0NW. 34 KT... 40NE 50SE 50SW 40NW. FORECAST VALID 27/1800Z 38.2N 45.5W MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 0NE 40SE 30SW 0NW. 34 KT... 50NE 70SE 60SW 50NW. FORECAST VALID 28/0600Z 39.2N 42.0W MAX WIND 65 KT...GUSTS 80 KT. 64 KT... 0NE 20SE 0SW 0NW. 50 KT... 30NE 40SE 40SW 30NW. 34 KT... 80NE 90SE 80SW 60NW. FORECAST VALID 28/1800Z 40.5N 38.7W MAX WIND 65 KT...GUSTS 80 KT. 64 KT... 0NE 20SE 0SW 0NW. 50 KT... 40NE 50SE 40SW 40NW. 34 KT...110NE 130SE 90SW 100NW. FORECAST VALID 29/0600Z 41.9N 35.9W MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 50NE 50SE 40SW 50NW. 34 KT...150NE 130SE 110SW 130NW. FORECAST VALID 29/1800Z 43.0N 33.8W MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 50NE 60SE 50SW 50NW. 34 KT...160NE 120SE 110SW 140NW. 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 30/1800Z 44.2N 27.8W...POST-TROP/EXTRATROP MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 0NE 50SE 50SW 0NW. 34 KT...130NE 100SE 90SW 120NW. OUTLOOK VALID 01/1800Z 45.5N 22.5W...POST-TROP/EXTRATROP MAX WIND 40 KT...GUSTS 50 KT. 34 KT...110NE 90SE 80SW 120NW. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 37.5N 50.6W NEXT ADVISORY AT 27/0300Z $$ FORECASTER D. ZELINSKY

Issued at 2100 UTC THU SEP 26 2024 007 WTNT24 KNHC 262040 TCMAT4 HURRICANE HELENE FORECAST/ADVISORY NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 2100 UTC THU SEP 26 2024 HURRICANE CENTER LOCATED NEAR 27.9N 84.6W AT 26/2100Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTH-NORTHEAST OR 25 DEGREES AT 20 KT ESTIMATED MINIMUM CENTRAL PRESSURE 951 MB MAX SUSTAINED WINDS 110 KT WITH GUSTS TO 135 KT. 64 KT....... 50NE 50SE 30SW 40NW. 50 KT.......100NE 100SE 50SW 50NW. 34 KT.......240NE 270SE 100SW 120NW. 12 FT SEAS..120NE 310SE 390SW 210NW. 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 27.9N 84.6W AT 26/2100Z AT 26/1800Z CENTER WAS LOCATED NEAR 26.7N 84.9W FORECAST VALID 27/0600Z 31.5N 83.7W...INLAND MAX WIND 90 KT...GUSTS 110 KT. 64 KT... 40NE 40SE 30SW 0NW. 50 KT...100NE 100SE 50SW 40NW. 34 KT...240NE 270SE 120SW 90NW. FORECAST VALID 27/1800Z 35.8N 85.0W...POST-TROP/EXTRATROP MAX WIND 40 KT...GUSTS 60 KT. 34 KT...120NE 330SE 0SW 0NW. FORECAST VALID 28/0600Z 37.0N 86.5W...POST-TROP/EXTRATROP MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 28/1800Z 37.1N 87.0W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 29/0600Z 37.1N 87.3W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 29/1800Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 27.9N 84.6W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 27/0000Z NEXT ADVISORY AT 27/0300Z $$ FORECASTER CANGIALOSI

5-Day Uncertainty Track last updated Thu, 26 Sep 2024 20:47:23 GMT


Wind Speed Probabilities last updated Thu, 26 Sep 2024 20:47:23 GMT