| 125mph peak forecast now. All four regional hurricane models show at least that strength or higher. (from NHC discussion) 10 to 15 feet of surge near landfall point, up from 8 to 12 feet. Track: https://www.nhc.noaa.gov/refresh/graphics_at5+shtml/?cone#contents Satellite Floater: https://www.star.nesdis.noaa.gov/GOES/floater.php?stormid=AL102023 Southeast US Satellite: https://www.star.nesdis.noaa.gov/GOES/sector_band.php?sat=G16§or=se&band=13&length=24 Radar: https://www.sfwmd.gov/weather-radar/current-weather-conditions/west-central-florida/large-scale-loop Hurricane Idalia Discussion Number 12 NWS National Hurricane Center Miami FL AL102023 1100 AM EDT Tue Aug 29 2023 WSR-88D radar data from Key West shows that Idalia's eye is becoming better defined at an elevation of 30,000 feet, although an eye has not yet become apparent in visible satellite imagery. A NOAA Hurricane Hunter aircraft reported a closed eye 20-25 n mi in diameter, SFMR winds as high as 70 kt, and a central pressure down to 976 mb. This pressure, and assuming some undersampling of the SFMR, supports an initial intensity of 75 kt. Idalia is moving just east of due north, or 005/12 kt, between a mid-level trough over the Gulf of Mexico and subtropical ridging over the Greater Antilles. A faster motion toward the north or north-northeast is expected while Idalia approaches the Florida coast through Wednesday morning. Confidence is increasing that Idalia will reach the coast of Florida adjacent to Apalachee Bay Wednesday morning, with all of the reliable deterministic track models honed in on that area. Track spread remains low during Idalia's expected turn toward the northeast and east-northeast in 48-60 hours, bringing the storm's center near or along the coast of the Carolinas. On days 3 through 5, there is significant uncertainty on whether Idalia will turn out to sea (as shown by the COAMPS-TC and HAFS models) or turn southward (as suggested by the global models). For now, the official forecast shows a slow motion at the end of the forecast period until the scenario becomes clearer. Idalia is currently over a maximum of oceanic heat content associated with the Loop Current, and water temperatures remain 30-31 degrees Celsius along the forecast path up until landfall. Vertical shear is also expected to be low for the next 18-24 hours, and these conditions are expected to foster rapid intensification before Idalia reaches the coast of Florida. The 06 UTC runs of all 4 regional hurricane models (HAFS-A, HAFS-B, HWRF, and HMON) show Idalia potentially reaching an intensity of 110-120 kt in 24 hours, and as a result, the new NHC intensity forecast indicates a peak intensity of 110 kt just before landfall. Weakening is forecast while the center of Idalia moves over land, but the system is expected to be a tropical storm while it moves near or along the coasts of Georgia and the Carolinas through Thursday. KEY MESSAGES: 1. Catastrophic impacts from storm surge inundation of 10 to 15 feet above ground level and destructive waves are expected somewhere between Aucilla River and Yankeetown, Florida. Life-threatening storm surge inundation is likely elsewhere along portions of the Florida Gulf Coast where a Storm Surge Warning is in effect. Residents in these areas should follow any advice or evacuation orders given by local officials. 2. There is the potential for destructive life-threatening winds where the core of Idalia moves onshore in the Big Bend region of Florida, with hurricane conditions expected elsewhere in portions of the Hurricane Warning area along the Florida Gulf Coast. Strong winds will also spread inland across portions of northern Florida and southern Georgia near the track of the center of Idalia where Hurricane Warnings are in effect. Residents in these areas should be prepared for long-duration power outages. 3. Areas of flash and urban flooding, some of which may be locally significant, are expected across portions of the west coast of Florida, the Florida Panhandle, and southern Georgia Tuesday into Wednesday, spreading into portions of the eastern Carolinas Wednesday into Thursday. 4. Heavy rainfall from Tropical Storm Idalia is expected across portions western Cuba and may produce areas of flash and urban flooding as well as landslides. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 24.6N 84.8W 75 KT 85 MPH 12H 30/0000Z 26.5N 84.6W 90 KT 105 MPH 24H 30/1200Z 29.3N 83.7W 110 KT 125 MPH 36H 31/0000Z 31.8N 81.7W 55 KT 65 MPH...INLAND 48H 31/1200Z 33.5N 78.8W 45 KT 50 MPH...OVER WATER 60H 01/0000Z 34.1N 75.6W 45 KT 50 MPH 72H 01/1200Z 33.8N 73.0W 45 KT 50 MPH 96H 02/1200Z 32.5N 70.2W 45 KT 50 MPH 120H 03/1200Z 32.0N 68.8W 45 KT 50 MPH $$ Forecaster Berg Hurricane Idalia Advisory Number 12 NWS National Hurricane Center Miami FL AL102023 1100 AM EDT Tue Aug 29 2023 ...IDALIA STRENGTHENING... ...LIFE-THREATENING STORM SURGE AND HURRICANE CONDITIONS EXPECTED ALONG PORTIONS OF THE GULF COAST OF FLORIDA TONIGHT AND WEDNESDAY... SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION ----------------------------------------------- LOCATION...24.6N 84.8W ABOUT 120 MI...190 KM W OF THE DRY TORTUGAS ABOUT 275 MI...440 KM SSW OF TAMPA FLORIDA MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H PRESENT MOVEMENT...N OR 5 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...976 MB...28.82 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Warning has been issued from Altamaha Sound, Georgia, northward to South Santee River, South Carolina. A Tropical Storm Watch has been issued from South Santee River northward to Surf City, North Carolina. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Englewood northward to Indian Pass, including Tampa Bay A Hurricane Warning is in effect for... * Cuban province of Pinar del Rio * Middle of Longboat Key northward to Indian Pass, including Tampa Bay A Tropical Storm Warning is in effect for... * Isle of Youth Cuba * Dry Tortugas Florida * Chokoloskee northward to the Middle of Longboat Key * West of Indian Pass to Mexico Beach * Sebastian Inlet Florida to South Santee River South Carolina A Storm Surge Watch is in effect for... * Chokoloskee northward to Englewood, including Charlotte Harbour * Mouth of the St. Mary's River to South Santee River South Carolina A Hurricane Watch is in effect for... * Englewood to the Middle of Longboat Key A Tropical Storm Watch is in effect for... * Lower Florida Keys west of the west end of the Seven Mile Bridge * South Santee River northward to Surf City North Carolina A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should be rushed to completion. 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 Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. 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 Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests elsewhere along the southeastern U.S. coast should monitor the progress of this system. Additional watches and warnings will likely be required later today. 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 1100 AM EDT (1500 UTC), the center of Hurricane Idalia was located near latitude 24.5 North, longitude 84.8 West. Idalia is moving toward the north near 14 mph (22 km/h). A faster motion toward the north and north-northeast is expected through early Wednesday while Idalia approaches the Gulf coast of Florida. A turn toward the northeast and east-northeast is forecast late Wednesday and Thursday, bringing the center of Idalia near or along the coasts of Georgia and the Carolinas. Maximum sustained winds have increased to near 85 mph (140 km/h) with higher gusts. Rapid intensification is expected before landfall, and Idalia is forecast to be a major hurricane when it reaches the Gulf coast of Florida Wednesday morning. Hurricane-force winds extend outward up to 15 miles (30 km) from the center and tropical-storm-force winds extend outward up to 160 miles (260 km). The estimated minimum central pressure from NOAA Hurricane Hunter aircraft data is 976 mb (28.82 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Idalia can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT5 and WMO header WTNT45 KNHC, and on the web at hurricanes.gov/text/MIATCDAT5.shtml 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... Aucilla River, FL to Yankeetown, FL...10-15 ft Yankeetown to Chassahowitzka, FL...7-11 ft Chassahowitzka, FL to Anclote River, FL...6-9 ft Ochlockonee River, FL to Aucilla River, FL...6-9 ft Anclote River, FL to Middle of Longboat Key, FL...4-7 ft Tampa Bay...4-7 ft Carrabelle, FL to Ochlockonee River, FL...4-7 ft Middle of Longboat Key, FL to Englewood, FL...3-5 ft Englewood, FL to Chokoloskee, FL...2-4 ft Charlotte Harbor...2-4 ft Indian Pass, FL to Carrabelle, FL...3-5 ft Mouth of the St. Mary's River to South Santee, SC...2-4 ft South Santee, SC to Surf City, NC...1-3 ft Chokoloskee, FL to East Cape Sable, FL...1-3 ft Flagler/Volusia County Line, FL to Mouth of St. Mary's River...1-3 ft Indian Pass to Mexico Beach...1 to 3 ft. Florida Keys...1-2 ft The deepest water will occur along the immediate coast in areas of onshore winds, 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. Elevated water levels along the southern coast of Pinar del Rio, Cuba will gradually subside today. WIND: Hurricane and tropical storm conditions are expected to continue within the warning areas in western Cuba for the next few hours. Hurricane conditions are expected within the hurricane warning area in Florida by tonight or early Wednesday, with tropical storm conditions beginning today. Tropical storm conditions are likely beginning in the Dry Tortugas and will begin within the tropical storm warning area along the Florida Gulf coast and the Florida west coast later today. Tropical storm conditions are expected to begin on Wednesday in the warning area along the east coast of Florida, Georgia, and South Carolina. Tropical storm conditions are possible within the watch area in South and North Carolina Wednesday night and Thursday. RAINFALL: Idalia is expected to produce the following rainfall amounts: Western Cuba: 4 to 7 inches, with isolated higher totals of 10 inches. Portions of the west coast of Florida, the Florida Panhandle, southeast Georgia and the eastern Carolinas: 4 to 8 inches from Tuesday into Thursday. Isolated higher totals of 12 inches possible, primarily near landfall in northern Florida. This rainfall may lead to flash and urban flooding, and landslides across western Cuba. Areas of flash and urban flooding, some of which may be locally significant, are expected across portions of the west coast of Florida, the Florida Panhandle, and southern Georgia Tuesday into Wednesday, spreading into portions of the eastern Carolinas Wednesday into Thursday. SURF: Swells generated by Idalia are affecting portions of the southern coast of Cuba and eastern Yucatan. These swells will spread northward along the eastern United States Gulf Coast during the next day or two. These swells are likely to cause life- threatening surf and rip current conditions. Please consult products from your local weather office. TORNADOES: A few tornadoes will be possible along the west central Florida coast through tonight. The tornado threat will also spread northward into the Florida Big Bend tonight, and toward southeast Georgia and the coastal Carolinas Wednesday. NEXT ADVISORY ------------- Next intermediate advisory at 200 PM EDT. Next complete advisory at 500 PM EDT. $$ Forecaster Berg |