479 WTNT34 KNHC 242351 TCPAT4 BULLETIN Tropical Storm Helene Intermediate Advisory Number 6A NWS National Hurricane Center Miami FL AL092024 800 PM EDT Tue Sep 24 2024 ...HELENE STRENGTHENING... SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION ---------------------------------------------- LOCATION...19.8N 85.3W ABOUT 115 MI...185 KM ESE OF COZUMEL MEXICO ABOUT 145 MI...235 KM S OF THE WESTERN TIP OF CUBA MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...991 MB...29.26 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Indian Pass southward to Flamingo * Tampa Bay * Charlotte Harbor A Hurricane Warning is in effect for... * Anclote River to Mexico Beach, Florida * Cabo Catoche to Tulum, Mexico A Hurricane Watch is in effect for... * Cuban province of Pinar del Rio * Englewood to Anclote River, including Tampa Bay A Tropical Storm Warning is in effect for... * Dry Tortugas * Lower and Middle Florida Keys west of the Channel 5 Bridge * Flamingo to Anclote River, including Tampa Bay * West of Mexico Beach to the Walton/Bay County Line * Rio Lagartos to Cabo Catoche, Mexico * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth A Tropical Storm Watch is in effect for... * Lake Okeechobee * Palm Beach/Martin County Line northward to the Savannah River A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within the next 36 hours. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area. Additional watches or warnings may be required for portions of Florida and the southeastern United States tonight or on Wednesday. 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 800 PM EDT (0000 UTC), the center of Tropical Storm Helene was located near latitude 19.8 North, longitude 85.3 West. Helene is moving toward the west-northwest near 12 mph (19 km/h). A turn toward the northwest is expected later tonight, followed by a general northward motion beginning on Wednesday and continuing through Friday. On the forecast track, the center of Helene will pass near the northeastern coast of the Yucatan Peninsula on Wednesday, move across the eastern Gulf of Mexico on Wednesday and Thursday, and reach the Big Bend coast of Florida late Thursday. Maximum sustained winds have increased to near 60 mph (95 km/h) with higher gusts. Additional strengthening is forecast, and Helene is expected to become a hurricane on Wednesday. The storm is forecast to rapidly strengthen over the eastern Gulf of Mexico and become a major hurricane on Thursday. Tropical-storm-force winds extend outward up to 175 miles (280 km) to the east of the center. The minimum central pressure based on Hurricane Hunter aircraft observations is 991 mb (29.26 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 RAINFALL: Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba and the Cayman Islands with isolated totals around 12 inches. Over the eastern Yucatan Peninsula, 4 to 6 inches of rain are expected with isolated totals over 8 inches. This rainfall brings a risk of considerable flooding. Over the Southeastern U.S., Helene is expected to produce total rain accumulations of 4 to 8 inches with isolated totals around 12 inches. This rainfall will likely result in areas of considerable flash and urban flooding, with areas of significant river flooding likely, including the risk of landslides in areas of steep terrain in the southern Appalachians. For a complete depiction of forecast rainfall associated with Helene, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero. STORM SURGE: The combination of a dangerous 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... Ochlockonee River, FL to Chassahowitzka, FL...10-15 ft Chassahowitzka, FL to Anclote River, FL...6-10 ft Indian Pass, FL to Ochlockonee River, FL...5-10 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 Englewood, FL to Flamingo, FL...3-5 ft Charlotte Harbor...3-5 ft For a complete depiction of areas at risk of storm surge inundation, please see the National Weather Service Peak Storm Surge Graphic, available at hurricanes.gov/graphics_at4.shtml?peakSurge. Storm surge could raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore winds along the southern coast of Pinar del Rio, Cuba, including the Isle of Youth. Storm surge could raise water levels by as much as 2 to 4 feet above ground level in areas of onshore winds within the warning area along the east coast of the Yucatan Peninsula. WIND: Hurricane conditions are expected in the hurricane warning area in Mexico on Wednesday. Hurricane conditions are expected within the U.S. hurricane warning area late Thursday. Tropical storm conditions are expected to begin in the tropical storm warning area in Florida on Wednesday and spread northward through Thursday. Tropical storm conditions are possible within the tropical storm watch area beginning Thursday. SURF: Swells generated by Helene will affect the southern coast of Cuba and the Yucatan Peninsula of Mexico during the next couple of days. Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast on Wednesday and Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next complete advisory at 1100 PM EDT. $$ Forecaster Pasch