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Tropical Storm Helene Public Advisory Number 16
2024-09-27 10:53:51| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Fri Sep 27 2024 467 WTNT34 KNHC 270853 TCPAT4 BULLETIN Tropical Storm Helene Advisory Number 16 NWS National Hurricane Center Miami FL AL092024 500 AM EDT Fri Sep 27 2024 ...HELENE WEAKENS TO A TROPICAL STORM AS IT MOVES FARTHER INLAND OVER GEORGIA... ...LIFE-THREATENING STORM SURGE, WINDS, AND HEAVY RAINS CONTINUE... SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...32.8N 83.0W ABOUT 40 MI...65 KM E OF MACON GEORGIA ABOUT 100 MI...165 KM SE OF ATLANTA GEORGIA MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...N OR 360 DEGREES AT 30 MPH...48 KM/H MINIMUM CENTRAL PRESSURE...968 MB...28.59 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: All Hurricane and Tropical Storm warnings have been discontinued along the Florida east coast south of the Flagler/Volusia county line, and along the Florida west coast south of the mouth of the Suwannee River. The Hurricane Warning for the Florida coast from the mouth of the Suwannee Rover to Mexico Beach has been changed to a Tropical Storm Warning. The Tropical Storm Warning has been discontinued for the Florida Gulf coast west of Indian Pass. The Storm Surge Warning for the Florida coast has been discontinued west of Indian Pass and south of Bonita Beach. The Hurricane Watch for the Florida West coast has been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Indian Pass to Bonita Beach * Tampa Bay A Tropical Storm Warning is in effect for... * The mouth of the Suwannee River to Indian Pass * The Flagler/Volusia county line 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. 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 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 500 AM EDT (0900 UTC), the center of Tropical Storm Helene was located near latitude 32.8 North, longitude 83.0 West. Helene is moving toward the north near 30 mph (48 km/h). A turn toward the north is expected this morning, taking the center over central and northeastern Georgia. After that, Helene is expected to turn northwestward and slow down over the Tennessee Valley later today and Saturday. Maximum sustained winds have decreased to near 70 mph (110 km/h) with higher gusts. Continued weakening is expected, and Helene is expected to become a post-tropical low this afternoon or tonight. However, 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. Tropical-storm-force winds extend outward up to 275 miles (445 km) mainly to the east of the center. The Marine Corp Air Station at Beaufort, South Carolina, recently reported a wind gust of 75 mph (120 km/h). The minimum central pressure based on surface observations is 968 mb (28.59 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 Chassahowitzka, FL to Anclote River, FL...4-7 ft Indian Pass, FL to Aucilla River, FL...3-6 ft Anclote River, FL to Englewood, FL...3-5 ft Tampa Bay...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 from northern Florida through eastern Georgia into southern South Carolina, and these conditions will continue spreading northward across the tropical storm warning areas in the Southeastern U.S. through today. 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 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 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 AM EDT. Next complete advisory at 1100 AM EDT. $$ Forecaster Beven
Category:Transportation and Logistics
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Tropical Storm Helene Forecast Advisory Number 16
2024-09-27 10:53:21| National Hurricane Center (Atlantic)
Issued at 0900 UTC FRI SEP 27 2024 000 WTNT24 KNHC 270853 TCMAT4 TROPICAL STORM HELENE FORECAST/ADVISORY NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 0900 UTC FRI SEP 27 2024 TROPICAL STORM CENTER LOCATED NEAR 32.8N 83.0W AT 27/0900Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTH OR 360 DEGREES AT 26 KT ESTIMATED MINIMUM CENTRAL PRESSURE 968 MB MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 80 KT. 50 KT....... 30NE 50SE 30SW 0NW. 34 KT.......240NE 240SE 100SW 60NW. 12 FT SEAS..240NE 380SE 390SW 0NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 32.8N 83.0W AT 27/0900Z...INLAND AT 27/0600Z CENTER WAS LOCATED NEAR 31.3N 83.3W...INLAND FORECAST VALID 27/1800Z 36.4N 84.5W...POST-TROP/INLAND MAX WIND 35 KT...GUSTS 50 KT. 34 KT...120NE 0SE 0SW 120NW. FORECAST VALID 28/0600Z 36.9N 87.3W...POST-TROP/EXTRATROP MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 28/1800Z 36.7N 87.3W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 29/0600Z 36.7N 87.0W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 29/1800Z 36.9N 86.0W...POST-TROP/EXTRATROP MAX WIND 20 KT...GUSTS 30 KT. FORECAST VALID 30/0600Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 32.8N 83.0W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 27/1200Z NEXT ADVISORY AT 27/1500Z $$ FORECASTER BEVEN
Category: Transportation and Logistics
Hurricane Isaac Forecast Discussion Number 6
2024-09-27 10:52:49| National Hurricane Center (Atlantic)
Issued at 500 AM AST Fri Sep 27 2024 256 WTNT45 KNHC 270852 TCDAT5 Hurricane Isaac Discussion Number 6 NWS National Hurricane Center Miami FL AL102024 500 AM AST Fri Sep 27 2024 Isaac has continued to become better organized since the prior advisory. The earlier warm spot noted on IR satellite imagery has persisted and warmed further, with sufficently cold -55 to -60 C convective cloud tops encircling the feature. A helpful AMSR2 pass that became available after the prior advisory also showed an eye feature on both the 89-GHz and 37-GHz channels, the latter showing a cyan ring. These features suggest that Isaac has become a hurricane, and the initial intensity has been raised to 65 kt for this advisory. Isaac still is moving generally eastward this morning, estimated at 090/10 kt. This motion with a gradual turn to the east-northeast should occur over the next couple of days as the hurricane remains steered mostly by deep-layer flow along the northern periphery of a mid-level ridge centered to the southeast of Isaac. Once again, how quick this forward motion ends up being will be critical for its ultimate track down the road, with a track bifurcation continuing between the GFS and ECMWF solutions occuring beyond 60 h as to how much the upstream trough located to its east is able to interact and pick up the cyclone. Despite the spread in the guidance, the consensus aids are not that much altered from the prior cycle, and the NHC track forecast is quite similar to the prior advisory. Additional intensification is expected while the vertical wind shear remains only low to moderate and Isaac continues to be over sufficently warm sea-surface temperatures (SSTs) with instability being aided by cold upper-level temperatures. After 36 h, SSTs drop to 24 C and lower as shear increases markedly, which should induce a gradual weakening trend. Both the GFS and ECMWF suggest the cyclone should lose its deep convection sometime in the 72-96 h period, marking its transition to post-tropical in that time frame. The NHC intensity forecast is on the high side of the guidance, but is generally in line with the latest GFS-based SHIPS and LGEM guidance. FORECAST POSITIONS AND MAX WINDS INIT 27/0900Z 37.0N 48.5W 65 KT 75 MPH 12H 27/1800Z 37.5N 45.9W 70 KT 80 MPH 24H 28/0600Z 38.8N 42.4W 75 KT 85 MPH 36H 28/1800Z 40.4N 39.3W 75 KT 85 MPH 48H 29/0600Z 41.8N 37.3W 70 KT 80 MPH 60H 29/1800Z 43.1N 35.9W 60 KT 70 MPH 72H 30/0600Z 44.0N 34.3W 55 KT 65 MPH 96H 01/0600Z 46.9N 30.4W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 02/0600Z 50.4N 26.2W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Papin
Category: Transportation and Logistics