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| #1109070 (Received by flhurricane at: 4:59 PM 26.Sep.2022) TCDAT4 Hurricane Ian Special Discussion Number 15 NWS National Hurricane Center Miami FL AL092022 500 PM EDT Mon Sep 26 2022 Ian continues to strengthen over the northwestern Caribbean Sea. The last report from the Air Force Hurricane Hunters around 1630 UTC found 700-mb flight-level winds of 79 kt. The inner core appears better organized, and the eyewall structure has greatly improved in radar imagery from the Cayman Islands. The 18 UTC satellite classifications from SAB and TAFB were a consensus T4.5/77 kt, but the continued improvement in satellite structure warrants raising the initial intensity to 85 kt for this advisory. Atmospheric and oceanic conditions remain very favorable for additional intensification during the next 24 h or so, as Ian moves over the very warm waters of the northwestern Caribbean Sea and the southeastern Gulf of Mexico while the shear remains quite low. The NHC intensity forecast calls for Ian to become a major hurricane before it reaches western Cuba early Tuesday. It is then forecast to reach its peak intensity over the southeastern Gulf of Mexico in 36 h. After that, southwesterly shear in association with a deep-layer trough over the eastern U.S. is forecast to significantly increase over the hurricane on Wednesday and Thursday, which will likely disrupt the vertical structure and import drier air into its circulation. Despite these less favorable conditions, Ian is still forecast to remain at or near major hurricane strength as it passes near the west-central coast of Florida on Wednesday and Thursday. The NHC intensity forecast agrees well with the latest IVCN and HCCA aids. Ian has made an expected turn toward the north-northwest, and its initial motion is 330/11 kt. The hurricane will move north-northwestward to northward over the next day or so as it is steered by a mid-level ridge to the east. A turn to the north-northeast with a decrease in forward speed is forecast on Wednesday and Thursday as the center of Ian moves near the west coast of Florida. The slower forward motion is likely to prolong the storm surge, wind, and rainfall impacts, especially along the west coast of Florida. The latest track guidance has come into better agreement on this scenario, although it is noted that small deviations to the shore-parallel track could have large implications on the impacts at particular locations along the west coast of Florida. The NHC track forecast has again been adjusted slightly eastward at 48-72 h, which follows the latest trends in the global model guidance and lies near but just west of the multi-model consensus aids. Based on the latest forecast and timing of expected impacts, Hurricane and Storm Surge Warnings have been issued along the west coast of Florida. Key Messages: 1. Life-threatening storm surge, hurricane-force winds, flash floods and possible mudslides are expected in portions of western Cuba beginning this evening and continuing into Tuesday. Devastating wind damage is possible where the core of Ian moves across western Cuba. Efforts to protect life and property should be rushed to completion. 2. There is the danger of life-threatening storm surge along much of the Florida west coast where a storm surge warning has been issued, with the highest risk from Fort Myers to the Tampa Bay region. Residents in these areas should listen to advice given by local officials. 3. Hurricane-force winds are expected in the hurricane warning area in west-central Florida beginning Wednesday morning with tropical storm conditions expected by late Tuesday. 4. Heavy rainfall will increase across the Florida Keys and south Florida Tuesday, spreading to central and northern Florida Wednesday and Thursday, potentially causing flash, urban and small stream flooding. Significant prolonged river flooding is likely across central Florida. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 20.3N 83.2W 85 KT 100 MPH 12H 27/0600Z 21.7N 83.8W 105 KT 120 MPH 24H 27/1800Z 23.6N 84.0W 115 KT 130 MPH 36H 28/0600Z 25.3N 83.9W 120 KT 140 MPH 48H 28/1800Z 26.7N 83.5W 115 KT 130 MPH 60H 29/0600Z 27.5N 83.2W 100 KT 115 MPH 72H 29/1800Z 28.1N 82.9W 75 KT 85 MPH 96H 30/1800Z 30.1N 82.3W 45 KT 50 MPH...INLAND 120H 01/1800Z 33.5N 82.0W 25 KT 30 MPH...INLAND $$ Forecaster Reinhart |
