National Hurricane Center (NHC) Atlantic Map

Issued at 2100 UTC FRI SEP 27 2024 000 WTNT25 KNHC 272033 TCMAT5 HURRICANE ISAAC FORECAST/ADVISORY NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102024 2100 UTC FRI SEP 27 2024 HURRICANE CENTER LOCATED NEAR 37.8N 45.3W AT 27/2100Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE EAST OR 80 DEGREES AT 14 KT ESTIMATED MINIMUM CENTRAL PRESSURE 976 MB EYE DIAMETER 20 NM MAX SUSTAINED WINDS 75 KT WITH GUSTS TO 90 KT. 64 KT....... 0NE 15SE 10SW 0NW. 50 KT....... 20NE 40SE 30SW 20NW. 34 KT....... 40NE 80SE 70SW 60NW. 12 FT SEAS.. 90NE 180SE 180SW 90NW. 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 37.8N 45.3W AT 27/2100Z AT 27/1800Z CENTER WAS LOCATED NEAR 37.5N 46.2W FORECAST VALID 28/0600Z 38.8N 42.7W MAX WIND 80 KT...GUSTS 100 KT. 64 KT... 10NE 20SE 15SW 10NW. 50 KT... 30NE 50SE 40SW 30NW. 34 KT... 80NE 100SE 80SW 80NW. FORECAST VALID 28/1800Z 40.3N 39.8W 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 29/0600Z 41.8N 37.9W MAX WIND 70 KT...GUSTS 85 KT. 64 KT... 0NE 20SE 15SW 0NW. 50 KT... 40NE 55SE 50SW 40NW. 34 KT...170NE 130SE 110SW 120NW. FORECAST VALID 29/1800Z 43.1N 36.3W MAX WIND 65 KT...GUSTS 80 KT. 64 KT... 0NE 0SE 20SW 0NW. 50 KT... 40NE 60SE 55SW 50NW. 34 KT...180NE 130SE 110SW 160NW. FORECAST VALID 30/0600Z 44.4N 34.5W...POST-TROPICAL MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 40NE 55SE 45SW 45NW. 34 KT...180NE 130SE 110SW 180NW. FORECAST VALID 30/1800Z 45.7N 32.7W...POST-TROPICAL MAX WIND 50 KT...GUSTS 60 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 01/1800Z 50.1N 29.9W...POST-TROP/EXTRATROP MAX WIND 45 KT...GUSTS 55 KT. 34 KT...190NE 110SE 90SW 110NW. OUTLOOK VALID 02/1800Z 52.9N 27.3W...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 37.8N 45.3W NEXT ADVISORY AT 28/0300Z $$ FORECASTER BUCCI

Issued at 228 PM EDT Fri Sep 27 2024

Issued at 205 PM EDT Fri Sep 27 2024

Issued at 159 PM EDT Fri Sep 27 2024

Issued at 153 PM EDT Fri Sep 27 2024

000
ABNT20 KNHC 271752
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM 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
Depression Helene, located inland over the southern Appalachians,
on Hurricane Isaac, located over the central Subtropical Atlantic
Ocean, and on recently-formed Tropical Storm Joyce, located over
the central Tropical Atlantic Ocean.

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...30 percent.

&&
Public Advisories on Tropical Storm Joyce are issued under WMO
header WTNT31 KNHC and under AWIPS header MIATCPAT1.
Forecast/Advisories on Tropical Storm Joyce are issued under WMO
header WTNT21 KNHC and under AWIPS header MIATCMAT1.

$$
Forecaster Bucci/Rosado

5-Day Uncertainty Track last updated Fri, 27 Sep 2024 17:48:15 GMT


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

Issued at 200 PM EDT Fri Sep 27 2024 000 WTNT34 KNHC 271746 TCPAT4 BULLETIN Tropical Depression Helene Intermediate Advisory Number 17A NWS National Hurricane Center Miami FL AL092024 200 PM EDT Fri Sep 27 2024 ...HELENE STILL PRODUCING HISTORIC AND CATASTROPHIC FLOODING OVER PORTIONS OF THE SOUTHEAST AND SOUTHERN APPALACHIANS... SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...36.6N 84.6W ABOUT 125 MI...205 KM SSE OF LOUISVILLE KENTUCKY MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...NNW OR 330 DEGREES AT 28 MPH...44 KM/H MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: All Tropical Storm Warnings have been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: There are no coastal watches or warnings in effect. For storm information specific to your area, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 200 PM EDT (1800 UTC), the center of Tropical Depression Helene was located near latitude 36.6 North, longitude 84.6 West. Helene is moving toward the north-northwest near 28 mph (44 km/h). A slowdown in forward speed is expected, and the depression is forecast to stall over the Tennessee Valley tonight and through the weekend. Maximum sustained winds have decreased to near 35 mph (55 km/h) with higher gusts. Continued slow weakening is expected, and Helene is forecast to become extratropical later this afternoon. The estimated minimum central pressure based on surface observations is 982 mb (29.00 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: Water levels will continue to recede along the Florida Gulf Coast and portions of the southeast U.S. coast throughout the day. WIND: Gusts to tropical-storm-force are still occurring in portions of the Appalachians and off the South Carolina coast, but they should subside by this evening. 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 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 complete advisory at 500 PM EDT. $$ Forecaster Cangialosi

...HELENE STILL PRODUCING HISTORIC AND CATASTROPHIC FLOODING OVER PORTIONS OF THE SOUTHEAST AND SOUTHERN APPALACHIANS... As of 2:00 PM EDT Fri Sep 27 the center of Helene was located near 36.6, -84.6 with movement NNW at 28 mph. The minimum central pressure was 982 mb with maximum sustained winds of about 35 mph.

Issued at 1146 AM EDT Fri Sep 27 2024

5-Day Uncertainty Track last updated Fri, 27 Sep 2024 14:41:53 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2024 15:37:27 GMT

5-Day Uncertainty Track last updated Fri, 27 Sep 2024 14:39:39 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2024 15:30:31 GMT

...HURRICANE ISAAC HEADING EASTWARD OVER THE NORTH CENTRAL ATLANTIC OCEAN... As of 11:00 AM AST Fri Sep 27 the center of Isaac was located near 37.4, -46.8 with movement ENE at 18 mph. The minimum central pressure was 981 mb with maximum sustained winds of about 75 mph.

Issued at 1100 AM AST Fri Sep 27 2024 535 WTNT35 KNHC 271438 CCA TCPAT5 BULLETIN Hurricane Isaac Advisory Number 7...Corrected NWS National Hurricane Center Miami FL AL102024 1100 AM AST Fri Sep 27 2024 Correct headline ...HURRICANE ISAAC HEADING EASTWARD OVER THE NORTH CENTRAL ATLANTIC OCEAN... SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...37.4N 46.8W ABOUT 1080 MI...1740 KM W OF THE AZORES MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H PRESENT MOVEMENT...ENE OR 65 DEGREES AT 18 MPH...30 KM/H MINIMUM CENTRAL PRESSURE...981 MB...28.97 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 Hurricane Isaac was located near latitude 37.4 North, longitude 46.8 West. Isaac is moving toward the east-northeast near 18 mph (30 km/h). A gradual turn to the east-northeast with a slight acceleration in forward speed is expected over the few days. Maximum sustained winds are near 75 mph (120 km/h) with higher gusts. Additional strengthening is expected during the next day or so followed by gradual weakening by the end of this weekend. Hurricane-force winds extend outward up to 15 miles (30 km) from the center and tropical-storm-force winds extend outward up to 70 miles (110 km). The estimated minimum central pressure is 981 mb (28.97 inches). HAZARDS AFFECTING LAND ---------------------- SURF: Swells generated by Isaac and a large wind fetch from a deep-layer trough 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 500 PM AST. $$ Forecaster Bucci

Issued at 1100 AM AST Fri Sep 27 2024 000 WTNT41 KNHC 271438 TCDAT1 Tropical Storm Joyce Discussion Number 1 NWS National Hurricane Center Miami FL AL112024 1100 AM AST Fri Sep 27 2024 Tropical Storm Joyce has formed over the central tropical Atlantic Ocean, becoming the tenth named storm in the basin this season. First-light visible satellite imagery showed low-level clouds moving westward, indicating the surface circulation has closed. Deep, organized convection has been persistent for the past day or so with decent outflow noted in the northern semicircle of the circulation. This initial intensity is set to 35 kt, representing the subjective satellite estimates from both TAFB and SAB. Joyce has a short window for potential intensification. For the next day or so, deep-layer vertical wind shear should be moderate-to-low with warm sea surface temperatures along the forecast track. Mid-level humidities around Joyce are sufficient, but expected to dry in the coming days. Global models predict the vertical wind shear should increase and the storm will likely experience dry air intrusions. The official forecast shows Joyce strengthening to a peak of 50 kt on Saturday, followed by gradual weakening through next week. Deep convection should be stripped away by Tuesday and Joyce is expected to become a remnant low at that point before opening into a trough. However, the GFS suggests this could happen even sooner. The storm is moving northwestward at 11 kt. A weak mid-level ridge centered over the eastern Atlantic Ocean is expected to steer Joyce generally northwestward for the next day or so, followed by a gradual turn to the north-northwest and north with a slowing forward speed. Model guidance is in relatively good agreement about this evolution and the NHC track forecast follows the various simple and corrected consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 18.1N 42.9W 35 KT 40 MPH 12H 28/0000Z 18.8N 44.3W 40 KT 45 MPH 24H 28/1200Z 19.4N 46.1W 50 KT 60 MPH 36H 29/0000Z 19.8N 47.7W 45 KT 50 MPH 48H 29/1200Z 20.7N 48.8W 40 KT 45 MPH 60H 30/0000Z 21.6N 49.4W 40 KT 45 MPH 72H 30/1200Z 22.6N 49.4W 35 KT 40 MPH 96H 01/1200Z 23.9N 48.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 02/1200Z...DISSIPATED $$ Forecaster Bucci

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 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

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

...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 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