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| #1149751 (Received by flhurricane at: 11:06 PM 27.Aug.2023) TCDAT5 Tropical Storm Idalia Discussion Number 6 NWS National Hurricane Center Miami FL AL102023 1000 PM CDT Sun Aug 27 2023 Idalia`s center has become embedded beneath a large burst of deep convection, with overshooting cloud-top temperatures as cold as -82 degrees Celsius. NOAA buoy 42056, located just to the east of the center, has reported maximum 1-minute sustained winds as high as 45 kt within the past hour or two. The anemometer height of the buoy is 4 meters, so converting the wind to a standard 10-meter height indicates that Idalia`s intensity is now up to at least 50 kt, which is the initial intensity for this advisory. An Air Force Reserve reconnaissance aircraft is scheduled to investigate Idalia in a few hours. The center has been moving erratically since earlier today, and may have even sagged southward, pulled toward the recently developed deep convection. A northward motion is expected to begin on Monday and continue through Tuesday as Idalia moves between a mid-level trough over the central Gulf of Mexico and strengthening ridging over the Greater Antilles. After 48 hours, a gradual turn toward the northeast and then east is anticipated due to a deeper trough that is expected to swing across the Great Lakes. No significant changes were required for the updated NHC track forecast compared to the previous prediction. The spread among the track models remains relatively low, and the official track continues to lie closest to the ECMWF and HCCA consensus aid. Idalia is sitting over very warm waters of about 30 degrees Celsius, and when it moves northward, it will be over the even deeper warm waters of the Loop Current in 24-36 hours. Although the trough over the Gulf could impart some shear over the system, this is likely to be offset by upper-level diffluence. Idalia has already strengthened more than anticipated, and the environment looks ripe for additional intensification, possibly rapid. The NHC intensity forecast has been increased and lies at the upper bound of the guidance. The new prediction now shows a 95-kt hurricane over the eastern Gulf of Mexico at 48 hours, but it should be stressed that additional strengthening to major hurricane strength is becoming increasingly likely before Idalia reaches the Gulf coast of Florida. Interests within the storm surge and hurricane watch areas are urged to prepare for possible significant impacts and monitor future updates to the forecast. KEY MESSAGES: 1. Idalia is forecast to become a hurricane by the time it reaches the southeastern Gulf of Mexico, and it could be near or at major hurricane strength when it reaches the Gulf coast of Florida. The risk continues to increase for a life-threatening storm surge and hurricane-force winds along portions of the west coast of Florida and the Florida Panhandle beginning as early as Tuesday. Storm surge and hurricane watches are in effect for portions of the west coast of Florida and the coast of the Florida Panhandle, and residents in these areas should monitor updates to the forecast and follow any advice given by local officials. 2. Scattered flash and urban flooding is expected across portions of the west coast of Florida, the Florida Panhandle, and southern Georgia late Tuesday night through Wednesday. Heavy rainfall may lead to flash flooding across portions of the Carolinas Wednesday into Thursday. 3. Hurricane-force winds are expected across portions of far western Cuba late Monday. Heavy rainfall is expected across portions of the eastern Yucatan and western Cuba and may produce areas of flash and urban flooding as well as landslides across western Cuba. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 19.8N 85.3W 50 KT 60 MPH 12H 28/1200Z 20.7N 85.1W 60 KT 70 MPH 24H 29/0000Z 22.2N 85.0W 70 KT 80 MPH 36H 29/1200Z 24.2N 84.9W 80 KT 90 MPH 48H 30/0000Z 26.8N 84.3W 95 KT 110 MPH 60H 30/1200Z 29.6N 82.8W 85 KT 100 MPH...INLAND 72H 31/0000Z 32.0N 80.1W 55 KT 65 MPH...OVER WATER 96H 01/0000Z 34.3N 73.4W 50 KT 60 MPH 120H 02/0000Z 34.4N 67.8W 50 KT 60 MPH $$ Forecaster Berg |
