5-Day Uncertainty Track last updated Fri, 27 Sep 2024 14:38:14 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2024 15:23:05 GMT

Issued at 1100 AM EDT Fri Sep 27 2024 000 WTNT44 KNHC 271436 TCDAT4 Tropical Storm Helene Discussion Number 17 NWS National Hurricane Center Miami FL AL092024 1100 AM EDT Fri Sep 27 2024 Helene has been racing northward and the low-level center is now located over the southern Appalachians. Strong bands of heavy rain and very gusty winds continue off and along the South Carolina coast. In addition, wind gusts to around hurricane force have been occurring this morning in portions of northeastern Georgia and the western portions of the Carolinas, especially in areas of higher terrain. The initial intensity is set at 40 kt, and these sustained winds are likely occurring off the south Carolina coast and over the Appalachians. The main hazard is the very heavy rainfall ongoing over portions of the southeastern U.S., which is causing historic and life-threatening flooding. Helene is expected to move slower to the northwest later today and then stall over the Tennessee Valley tonight and through the weekend as it merges with a mid- to upper-level low. This merger will also lead to extratropical transition, which is expected to occur later today. The expected slow motion could result in significant flooding over the Ohio and Tennessee Valleys, and over the southern Appalachians through the weekend. KEY MESSAGES: 1. Historic, catastrophic and life-threatening flash and urban flooding, including numerous significant landslides, will continue across portions of the Southern Appalachians through this evening. Widespread significant river flooding is ongoing, some of which will be major to record breaking. 2. Damaging wind gusts will continue over portions of Georgia, the Carolinas, Tennessee, and Kentucky today, particularly over the higher terrain of the southern Appalachians. 3. There is a possibility of long-duration power outages in portions of the southeast U.S. 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. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 35.1N 83.8W 40 KT 45 MPH 12H 28/0000Z 37.3N 85.6W 30 KT 35 MPH...POST-TROP/EXTRATROP 24H 28/1200Z 37.5N 86.5W 25 KT 30 MPH...POST-TROP/EXTRATROP 36H 29/0000Z 37.5N 86.4W 20 KT 25 MPH...POST-TROP/EXTRATROP 48H 29/1200Z 37.5N 86.1W 20 KT 25 MPH...POST-TROP/EXTRATROP 60H 30/0000Z 37.6N 85.7W 20 KT 25 MPH...POST-TROP/EXTRATROP 72H 30/1200Z...DISSIPATED $$ Forecaster Cangialosi/Rosado

Issued at 1500 UTC FRI SEP 27 2024 000 FONT14 KNHC 271436 PWSAT4 TROPICAL STORM HELENE WIND SPEED PROBABILITIES NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 1500 UTC FRI SEP 27 2024 AT 1500Z THE CENTER OF TROPICAL STORM HELENE WAS LOCATED NEAR LATITUDE 35.1 NORTH...LONGITUDE 83.8 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 40 KTS...45 MPH...75 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 12Z FRI 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 12Z FRI 00Z SAT 12Z SAT 00Z SUN 12Z SUN 12Z MON 12Z TUE PERIODS TO TO TO TO TO TO TO 00Z SAT 12Z SAT 00Z SUN 12Z SUN 12Z MON 12Z TUE 12Z WED FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT CHARLOTTE NC 34 99 X(99) X(99) X(99) X(99) X(99) X(99) FLORENCE SC 34 99 X(99) X(99) X(99) X(99) X(99) X(99) COLUMBIA SC 34 99 X(99) X(99) X(99) X(99) X(99) X(99) GEORGETOWN SC 34 99 X(99) X(99) X(99) X(99) X(99) X(99) CHARLESTON SC 34 99 X(99) X(99) X(99) X(99) X(99) X(99) BEAUFORT MCAS 34 99 X(99) X(99) X(99) X(99) X(99) X(99) ATLANTA GA 34 19 X(19) X(19) X(19) X(19) X(19) X(19) AUGUSTA GA 34 99 X(99) X(99) X(99) X(99) X(99) X(99) SAVANNAH GA 34 99 X(99) X(99) X(99) X(99) X(99) X(99) MACON GA 34 28 X(28) X(28) X(28) X(28) X(28) X(28) $$ FORECASTER CANGIALOSI

...HELENE PRODUCING HISTORIC AND CATASTROPHIC FLOODING OVER PORTIONS OF THE SOUTHEAST AND SOUTHERN APPALACHIANS... ...FLASH FLOOD EMERGENCIES IN EFFECT FOR METROPOLITAN ATLANTA, AND MUCH OF UPSTATE SOUTH CAROLINA AND WESTERN NORTH CAROLINA... As of 11:00 AM EDT Fri Sep 27 the center of Helene was located near 35.1, -83.8 with movement N at 32 mph. The minimum central pressure was 975 mb with maximum sustained winds of about 45 mph.

Issued at 1100 AM EDT Fri Sep 27 2024 000 WTNT34 KNHC 271436 TCPAT4 BULLETIN Tropical Storm Helene Advisory Number 17 NWS National Hurricane Center Miami FL AL092024 1100 AM EDT Fri Sep 27 2024 ...HELENE PRODUCING HISTORIC AND CATASTROPHIC FLOODING OVER PORTIONS OF THE SOUTHEAST AND SOUTHERN APPALACHIANS... ...FLASH FLOOD EMERGENCIES IN EFFECT FOR METROPOLITAN ATLANTA, AND MUCH OF UPSTATE SOUTH CAROLINA AND WESTERN NORTH CAROLINA... SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...35.1N 83.8W ABOUT 30 MI...50 KM SW OF BRYSON CITY NORTH CAROLINA ABOUT 105 MI...165 KM NNE OF ATLANTA GEORGIA MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...N OR 350 DEGREES AT 32 MPH...52 KM/H MINIMUM CENTRAL PRESSURE...975 MB...28.80 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Tropical Storm Warning for the Georgia coast has been discontinued. All Storm Surge Warnings have been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Savannah River northward to Little River Inlet A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 1100 AM EDT (1500 UTC), the center of Tropical Storm Helene was located near latitude 35.1 North, longitude 83.8 West. Helene is moving toward the north near 32 mph (52 km/h). A slowdown in forward speed is expected soon, and the storm is forecast to stall over the Tennessee Valley tonight and through the weekend. Maximum sustained winds have decreased to near 45 mph (75 km/h) with higher gusts. Continued weakening is expected, and Helene is forecast to become extratropical later today. Tropical-storm-force winds extend outward up to 345 miles (555 km) east of the center. The estimated minimum central pressure based on surface observations is 975 mb (28.80 inches). A weather station on Sassafras Mountain reported a sustained wind of 41 mph (67 km/h) with a gust of 61 mph (98 km/h). A coastal observation at Murrells Inlet recently reported a sustained wind of 38 mph (61 km/h) with a gust of 46 mph (74 km/h). 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: Water levels will continue to receed along the Florida Gulf Coast and portions of the southeast U.S. coast throughout the day. WIND: Tropical storm conditions are occurring along much of the South Carolina coast, and these conditions will continue for the next several hours. Strong, damaging winds, especially in gusts, will also continue as far inland as the higher terrain of the southern Appalachians. RAINFALL: Over portions of the Central and Southern Appalachians, Helene is expected to produce additional rainfall amounts of 3 to 6 inches leading to total rain accumulations of 6 to 12 inches, with isolated totals around 20 inches. This rainfall will result in catastrophic and potentially life-threatening flash and urban flooding, along with significant and record river flooding. Numerous significant landslides are expected in steep terrain across the Southern Appalachians. For a complete depiction of forecast rainfall associated with Tropical Storm 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: Tornadoes are possible today across eastern South Carolina, central and eastern North Carolina, and southern Virginia. SURF: Swells generated by Helene will affect the coasts of Georgia and the Carolinas during the next day or so. 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 200 PM EDT. Next complete advisory at 500 PM EDT. $$ Forecaster Cangialosi/Rosado

Issued at 1500 UTC FRI SEP 27 2024 000 WTNT24 KNHC 271436 TCMAT4 TROPICAL STORM HELENE FORECAST/ADVISORY NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 1500 UTC FRI SEP 27 2024 TROPICAL STORM CENTER LOCATED NEAR 35.1N 83.8W AT 27/1500Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE NORTH OR 350 DEGREES AT 28 KT ESTIMATED MINIMUM CENTRAL PRESSURE 975 MB MAX SUSTAINED WINDS 40 KT WITH GUSTS TO 60 KT. 34 KT.......120NE 300SE 0SW 0NW. 12 FT SEAS.. 0NE 420SE 510SW 0NW. 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 35.1N 83.8W AT 27/1500Z AT 27/1200Z CENTER WAS LOCATED NEAR 34.4N 83.2W FORECAST VALID 28/0000Z 37.3N 85.6W...POST-TROP/EXTRATROP MAX WIND 30 KT...GUSTS 50 KT. FORECAST VALID 28/1200Z 37.5N 86.5W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 29/0000Z 37.5N 86.4W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 29/1200Z 37.5N 86.1W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 30/0000Z 37.6N 85.7W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 30/1200Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 35.1N 83.8W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 27/1800Z NEXT ADVISORY AT 27/2100Z $$ FORECASTER CANGIALOSI

Issued at 1500 UTC FRI SEP 27 2024 000 FONT11 KNHC 271435 PWSAT1 TROPICAL STORM JOYCE WIND SPEED PROBABILITIES NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112024 1500 UTC FRI SEP 27 2024 AT 1500Z THE CENTER OF TROPICAL STORM JOYCE WAS LOCATED NEAR LATITUDE 18.1 NORTH...LONGITUDE 42.9 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 35 KTS...40 MPH...65 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 12Z FRI 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 12Z FRI 00Z SAT 12Z SAT 00Z SUN 12Z SUN 12Z MON 12Z TUE PERIODS TO TO TO TO TO TO TO 00Z SAT 12Z SAT 00Z SUN 12Z SUN 12Z MON 12Z TUE 12Z WED FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT $$ FORECASTER BUCCI

...TROPICAL STORM JOYCE FORMS OVER THE CENTRAL TROPICAL ATLANTIC OCEAN... As of 11:00 AM AST Fri Sep 27 the center of Joyce was located near 18.1, -42.9 with movement NW at 13 mph. The minimum central pressure was 1006 mb with maximum sustained winds of about 40 mph.

Issued at 1100 AM AST Fri Sep 27 2024 000 WTNT31 KNHC 271435 TCPAT1 BULLETIN Tropical Storm Joyce Advisory Number 1 NWS National Hurricane Center Miami FL AL112024 1100 AM AST Fri Sep 27 2024 ...TROPICAL STORM JOYCE FORMS OVER THE CENTRAL TROPICAL ATLANTIC OCEAN... SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...18.1N 42.9W ABOUT 1325 MI...2130 KM E OF THE NORTHERN LEEWARD ISLANDS MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 1100 AM AST (1500 UTC), the center of Tropical Storm Joyce was located near latitude 18.1 North, longitude 42.9 West. Joyce is moving toward the northwest near 13 mph (20 km/h) and this general motion is expected to continue through Sunday with a gradually slower forward speed. On Monday, a gradual turn to the north is forecast. Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Gradual strengthening is expected through Saturday, followed by gradual weakening through early next week. Tropical-storm-force winds extend outward up to 70 miles (110 km) from the center. The estimated minimum central pressure is 1006 mb (29.71 inches). HAZARDS AFFECTING LAND ---------------------- None NEXT ADVISORY ------------- Next complete advisory at 500 PM AST. $$ Forecaster Bucci

Issued at 1500 UTC FRI SEP 27 2024 000 WTNT21 KNHC 271435 TCMAT1 TROPICAL STORM JOYCE FORECAST/ADVISORY NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112024 1500 UTC FRI SEP 27 2024 TROPICAL STORM CENTER LOCATED NEAR 18.1N 42.9W AT 27/1500Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE NORTHWEST OR 310 DEGREES AT 11 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1006 MB MAX SUSTAINED WINDS 35 KT WITH GUSTS TO 45 KT. 34 KT....... 60NE 0SE 0SW 0NW. 12 FT SEAS.. 30NE 0SE 0SW 30NW. 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 18.1N 42.9W AT 27/1500Z AT 27/1200Z CENTER WAS LOCATED NEAR 17.8N 42.4W FORECAST VALID 28/0000Z 18.8N 44.3W MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 80NE 30SE 0SW 30NW. FORECAST VALID 28/1200Z 19.4N 46.1W MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 20NE 10SE 0SW 10NW. 34 KT... 80NE 30SE 20SW 50NW. FORECAST VALID 29/0000Z 19.8N 47.7W MAX WIND 45 KT...GUSTS 55 KT. 34 KT... 80NE 40SE 20SW 50NW. FORECAST VALID 29/1200Z 20.7N 48.8W MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 80NE 40SE 20SW 50NW. FORECAST VALID 30/0000Z 21.6N 49.4W MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 70NE 50SE 20SW 30NW. FORECAST VALID 30/1200Z 22.6N 49.4W MAX WIND 35 KT...GUSTS 45 KT. 34 KT... 60NE 50SE 0SW 0NW. 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 01/1200Z 23.9N 48.8W...POST-TROP/REMNT LOW MAX WIND 30 KT...GUSTS 40 KT. OUTLOOK VALID 02/1200Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 18.1N 42.9W NEXT ADVISORY AT 27/2100Z $$ FORECASTER BUCCI

Issued at 1100 AM AST Fri Sep 27 2024 505 WTNT45 KNHC 271434 TCDAT5 Hurricane Isaac Discussion Number 7 NWS National Hurricane Center Miami FL AL102024 1100 AM AST Fri Sep 27 2024 Isaac is holding steady this morning. Geostationary satellite data has shown consistent periodic bursts of convection wrapping around a small eye. Subjective and objective Dvorak estimates range widely from 35 kt to 73 kt and the initial intensity is held at 65 kt for this advisory, closest to the SAB classification. The hurricane is moving eastward at 12 kt. Isaac is moving along the northern periphery of a mid-level ridge and should gradually turn to the east-northeast over the next couple of days. Models are more in agreement this cycle and show a more northeastward turn on days 4 and 5 as Isaac interacts with an upper-level trough located to its east. The latest track forecast is similar to the previous forecast through 72 h and slightly to the north at forecast periods beyond. Isaac could still strengthen further over the next day or so. While the vertical wind shear is expected to be strong-to-moderate, the upper-level divergence is forecast to increase and sea surface temperature should be relatively sufficient. Beyond a day or so, oceanic and environmental conditions become less conducive, which should begin to weaken Isaac by Saturday night or Sunday. The official intensity forecast is very similar to previous advisory, with a peak intensity of 75 kt by Saturday and the cyclone becoming extratropical by early next week. However, global models show the system losing its deep convection by Monday, and the official forecast now predicts Isaac becoming a post-tropical cyclone at that point. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 37.4N 46.8W 65 KT 75 MPH 12H 28/0000Z 38.1N 44.2W 70 KT 80 MPH 24H 28/1200Z 39.4N 40.9W 75 KT 85 MPH 36H 29/0000Z 41.0N 38.4W 75 KT 85 MPH 48H 29/1200Z 42.4N 36.6W 70 KT 80 MPH 60H 30/0000Z 43.7N 35.1W 60 KT 70 MPH 72H 30/1200Z 44.8N 33.0W 55 KT 65 MPH...POST-TROPICAL 96H 01/1200Z 48.0N 29.6W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 02/1200Z 52.1N 25.0W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Bucci

Issued at 1500 UTC FRI SEP 27 2024 927 FONT15 KNHC 271433 PWSAT5 HURRICANE ISAAC WIND SPEED PROBABILITIES NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102024 1500 UTC FRI SEP 27 2024 AT 1500Z THE CENTER OF HURRICANE ISAAC WAS LOCATED NEAR LATITUDE 37.4 NORTH...LONGITUDE 46.8 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 65 KTS...75 MPH...120 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 12Z FRI 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 12Z FRI 00Z SAT 12Z SAT 00Z SUN 12Z SUN 12Z MON 12Z TUE PERIODS TO TO TO TO TO TO TO 00Z SAT 12Z SAT 00Z SUN 12Z SUN 12Z MON 12Z TUE 12Z WED FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT SANTA CRUZ AZO 34 X X( X) 1( 1) 3( 4) 3( 7) X( 7) X( 7) $$ FORECASTER BUCCI

Issued at 1500 UTC FRI SEP 27 2024 000 WTNT25 KNHC 271432 TCMAT5 HURRICANE ISAAC FORECAST/ADVISORY NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102024 1500 UTC FRI SEP 27 2024 HURRICANE CENTER LOCATED NEAR 37.4N 46.8W AT 27/1500Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE EAST-NORTHEAST OR 65 DEGREES AT 16 KT ESTIMATED MINIMUM CENTRAL PRESSURE 981 MB MAX SUSTAINED WINDS 65 KT WITH GUSTS TO 80 KT. 64 KT....... 0NE 15SE 0SW 0NW. 50 KT....... 20NE 40SE 30SW 20NW. 34 KT....... 40NE 60SE 60SW 60NW. 12 FT SEAS.. 70NE 150SE 150SW 240NW. 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 37.4N 46.8W AT 27/1500Z AT 27/1200Z CENTER WAS LOCATED NEAR 37.1N 47.7W FORECAST VALID 28/0000Z 38.1N 44.2W MAX WIND 70 KT...GUSTS 85 KT. 64 KT... 0NE 20SE 15SW 0NW. 50 KT... 30NE 50SE 40SW 30NW. 34 KT... 60NE 80SE 70SW 60NW. FORECAST VALID 28/1200Z 39.4N 40.9W MAX WIND 75 KT...GUSTS 90 KT. 64 KT... 15NE 20SE 15SW 10NW. 50 KT... 40NE 50SE 40SW 40NW. 34 KT...120NE 120SE 100SW 100NW. FORECAST VALID 29/0000Z 41.0N 38.4W MAX WIND 75 KT...GUSTS 90 KT. 64 KT... 15NE 20SE 15SW 10NW. 50 KT... 40NE 55SE 50SW 40NW. 34 KT...170NE 130SE 110SW 120NW. FORECAST VALID 29/1200Z 42.4N 36.6W MAX WIND 70 KT...GUSTS 85 KT. 64 KT... 0NE 20SE 15SW 10NW. 50 KT... 40NE 60SE 55SW 50NW. 34 KT...180NE 130SE 110SW 160NW. FORECAST VALID 30/0000Z 43.7N 35.1W MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 40NE 55SE 45SW 45NW. 34 KT...180NE 130SE 110SW 180NW. FORECAST VALID 30/1200Z 44.8N 33.0W...POST-TROPICAL MAX WIND 55 KT...GUSTS 65 KT. 50 KT... 0NE 50SE 35SW 30NW. 34 KT...180NE 130SE 110SW 160NW. 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 01/1200Z 48.0N 29.6W...POST-TROP/EXTRATROP MAX WIND 45 KT...GUSTS 55 KT. 34 KT...190NE 110SE 90SW 110NW. OUTLOOK VALID 02/1200Z 52.1N 25.0W...POST-TROP/EXTRATROP MAX WIND 35 KT...GUSTS 45 KT. 34 KT...190NE 180SE 80SW 0NW. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 37.4N 46.8W NEXT ADVISORY AT 27/2100Z $$ FORECASTER BUCCI

Storm Surge Watch/Warning Map last updated Fri, 27 Sep 2024 12:00:59 GMT

Issued at 800 AM EDT Fri Sep 27 2024 000 WTNT34 KNHC 271152 TCPAT4 BULLETIN Tropical Storm Helene Intermediate Advisory Number 16A NWS National Hurricane Center Miami FL AL092024 800 AM EDT Fri Sep 27 2024 ...HELENE PRODUCING DAMAGING GUSTY WINDS AND LIFE-THREATENING FLOODING OVER PORTIONS OF THE SOUTHEAST AND SOUTHERN APPALACHIANS... ...FLASH FLOOD EMERGENCY IN EFFECT FOR METROPOLITAN ATLANTA... SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...34.2N 83.0W ABOUT 35 MI...60 KM SSW OF CLEMSON SOUTH CAROLINA ABOUT 80 MI...130 KM ENE OF ATLANTA GEORGIA MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H PRESENT MOVEMENT...N OR 360 DEGREES AT 30 MPH...48 KM/H MINIMUM CENTRAL PRESSURE...972 MB...28.70 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Tropical Storm Warning along the Florida Gulf Coast from the mouth of the Suwannee River to Indian Pass has been discontinued. The Tropical Storm Warning along the east coast of Florida and extreme southeastern Georgia from the Flagler/Volusia County Line to Altamaha Sound has been discontinued. The Storm Surge Warning for the Florida coast has been discontinued south of the Middle of Longboat Key. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Indian Pass to Middle of Longboat Key, Florida * Tampa Bay A Tropical Storm Warning is in effect for... * Altamaha Sound northward 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. 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. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning 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 AM EDT (1200 UTC), the center of Tropical Storm Helene was located near latitude 34.2 North, longitude 83.0 West. Helene is moving toward the north near 30 mph (48 km/h). Helene is expected to turn northwestward and slow down over the Tennessee Valley later today and Saturday. Maximum sustained winds have decreased to near 60 mph (95 km/h) with higher gusts. Continued weakening is expected, and Helene is expected to become a post-tropical low this afternoon or tonight. However, damaging wind gusts will penetrate far inland across the southeastern United States, including over the higher terrain of the southern Appalachians. Tropical-storm-force winds extend outward up to 275 miles (445 km) mainly to the east of the center. An observation in Brasstown Bald, Georgia recently reported a wind gust of 72 mph (116 km/h). An observation in Dewees Island, South Carolina, recently reported a sustained wind of 46 mph (74 km/h) and a gust of 62 mph (100 km/h). The minimum central pressure based on surface observations is 972 mb (28.70 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... Aucilla River, FL to Chassahowitzka, FL...5-10 ft Indian Pass, FL to Aucilla River, FL...3-6 ft Chassahowitzka, FL to Anclote River, FL...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: Tropical storm conditions are occurring along much of the Georgia and South Carolina coasts, and these conditions will continue for the next several hours. Strong, damaging winds, especially in gusts, will also continue 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 and record 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: Tornadoes are possible this morning over parts of eastern Georgia, and through this afternoon over the Carolinas and southern Virginia. SURF: Swells generated by Helene will affect the coasts of Georgia and the Carolinas during the next day or so. 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 AM EDT. $$ Forecaster Cangialosi/Harrigan

000
ABNT20 KNHC 271146
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Fri Sep 27 2024

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

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm Helene, located inland over northeast Georgia and on recently
upgraded Hurricane Isaac, located over the central Subtropical
Atlantic Ocean.

Central Tropical Atlantic (AL98):
Showers and thunderstorms associated with an area of low pressure
located midway in between the Cabo Verde Islands and the Lesser
Antilles continues to become better organized. This disturbance is
already producing gale-force winds. Environmental conditions are
conducive for further development and a tropical depression or storm
could form today while the system moves generally westward to
west-northwestward at 10 to 15 mph. The system is then forecast to
slow down and turn north-northwestward by this weekend. Additional
information on this system, including gale warnings, can be found in
High Seas Forecasts issued by the National Weather Service.
* 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, potentially entering the Gulf of Mexico by
the end of next week.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...30 percent.

Eastern Tropical Atlantic:
An area of low pressure could form over the eastern tropical
Atlantic by the early to middle part of next week. Environmental
conditions are expected to be conducive for slow development
thereafter while the system moves generally northwestward at 10 to
15 mph.
* Formation chance through 48 hours...low...near 0 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/Rosado

Potential Storm Surge Flooding Map last updated Fri, 27 Sep 2024 09:57:12 GMT

Probabilistic Storm Surge Graphics last updated Fri, 27 Sep 2024 09:31:33 GMT

Issued at 430 AM CDT Fri Sep 27 2024

5-Day Uncertainty Track last updated Fri, 27 Sep 2024 09:00:12 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2024 09:00:12 GMT