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Hurricane Helene Public Advisory Number 12
2024-09-26 10:51:51| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Thu Sep 26 2024 000 WTNT34 KNHC 260851 TCPAT4 BULLETIN Hurricane Helene Advisory Number 12 NWS National Hurricane Center Miami FL AL092024 400 AM CDT Thu Sep 26 2024 ...HELENE STRENGTHENING AND EXPECTED TO BRING CATASTROPHIC WINDS AND STORM SURGE TO THE NORTHEASTERN GULF COAST... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION... SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...24.2N 86.2W ABOUT 350 MI...560 KM SW OF TAMPA FLORIDA ABOUT 385 MI...625 KM S OF APALACHICOLA FLORIDA MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H PRESENT MOVEMENT...NNE OR 15 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...966 MB...28.53 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 * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth 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 Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. 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. 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 400 AM CDT (0900 UTC), the center of Hurricane Helene was located near latitude 24.2 North, longitude 86.2 West. Helene is moving toward the north-northeast near 12 mph (19 km/h). This general motion is expected to continued with a significant increase in forward speed during the next 24 hours. On the forecast track, Helene will move across the eastern Gulf of Mexico today and cross the Florida Big Bend coast this evening or early Friday morning. 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 90 mph (150 km/h) with higher gusts. Strengthening is forecast, and Helene is expected to be a major hurricane when it reaches the Florida Big Bend coast this evening. Weakening is expected after landfall, but Helene's 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 345 miles (555 km). The Key West Naval Air Station recently reported sustained winds of 41 mph (66 km/h) and a wind gust of 64 mph (103 km/h). The estimated minimum central pressure based on Air Force Reserve Hurricane Hunter aircraft data is 966 mb (28.53 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 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. WIND: Hurricane conditions are expected within the U.S. hurricane warning area late today, with tropical storm conditions beginning this morning. Tropical storm conditions are spreading across the Florida Keys at this time, and they are expected to spread northward across the rest of Florida, Georgia, and South Carolina through tonight. Tropical storm conditions are expected over portions of the warning area in western Cuba during the next few hours. RAINFALL: Hurricane Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba, the Cayman Islands and the northeast Yucatan Peninsula, with isolated totals around 12 inches. This rainfall brings a risk of considerable flooding. 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 18 inches. This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Numerous 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. TORNADOES: The risk for several tornadoes will gradually increase today through tonight. The greatest threat is expected from parts of northern Florida into southeast Georgia, the Midlands and Low Country of South Carolina, and southern North Carolina. 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 today. 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 700 AM CDT. Next complete advisory at 1000 AM CDT. $$ Forecaster Beven
Category:Transportation and Logistics
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Tropical Storm Isaac Graphics
2024-09-26 10:43:02| National Hurricane Center (Atlantic)
5-Day Uncertainty Track last updated Thu, 26 Sep 2024 08:43:02 GMT Wind Speed Probabilities last updated Thu, 26 Sep 2024 09:29:24 GMT
Category: Transportation and Logistics
Tropical Storm Isaac Forecast Discussion Number 2
2024-09-26 10:40:23| National Hurricane Center (Atlantic)
Issued at 500 AM AST Thu Sep 26 2024 000 WTNT45 KNHC 260840 TCDAT5 Tropical Storm Isaac Discussion Number 2 NWS National Hurricane Center Miami FL AL102024 500 AM AST Thu Sep 26 2024 Isaac's structure on satellite looks fairly healthy for a high-latitude tropical cyclone. There are plenty of curved banding features rotating around the estimated center on IR satellite, matched by a recent AMSR2 microwave pass also showing convective banding. While the cloud top temperatures are not that cold, only -50 to -60 C, that is rather typical for a tropical cyclone along the axis of an upper-level trough with a depressed tropopause. Based on the earlier scatterometer wind data, plus a DMINT estimate from the AMSR2 pass of 46 kt, the initial intensity is held at 45 kt this advisory. The tropical storm is continuing eastward this morning at 90/10 kt. This general motion, albeit with a gradual turn more east-northeastward is expected over the next several days as Isaac slowly accelerates under the influence of mid-level ridging to the southeast of the storm. The track guidance is in pretty good agreement in the short-term. However, differences primarily in the along-track direction begin to be evident beyond 48 h, which could ultimately play a role in more notable across-track differences shown between the GFS and ECMWF solutions by early next week. For now, the NHC track forecast is very similar to the previous track forecast, and favors a solution very similar to the HFIP corrected consensus approach (HCCA) and ECMWF track. Given the storm's healthy current structure, there is an opportunity for it to intensify over the next couple of days. During this time span, sea-surface temperatures (SSTs) hover between 26-27 C, colder than normal upper-level temperatures should aid tropospheric instability, and vertical wind shear is forecast to remain in the 15-20 kt range, in the same direction as the storm motion. The simulated IR imagery from the latest ECMWF and GFS runs also show Isaac attempting to clear out an eye occasionally in the 36-60 h period. These signals suggest that Isaac could become a hurricane, and that is now explicitly reflected in the latest NHC forecast, which is very close to the latest HCCA consensus aid. After 60 h, shear increases markedly as SSTs also decrease, which should lead to weakening, and Isaac is forecast to become post-tropical sometime near the end of the forecast as it passes by to the north of the Azores. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 37.1N 52.8W 45 KT 50 MPH 12H 26/1800Z 37.2N 50.9W 50 KT 60 MPH 24H 27/0600Z 37.6N 48.1W 55 KT 65 MPH 36H 27/1800Z 38.3N 44.9W 60 KT 70 MPH 48H 28/0600Z 39.4N 41.2W 65 KT 75 MPH 60H 28/1800Z 40.5N 37.9W 65 KT 75 MPH 72H 29/0600Z 41.8N 34.0W 60 KT 70 MPH 96H 30/0600Z 43.0N 27.2W 55 KT 65 MPH 120H 01/0600Z 43.4N 19.4W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Papin
Category: Transportation and Logistics