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| #1109032 (Received by flhurricane at: 10:59 AM 26.Sep.2022) TCDAT4 Hurricane Ian Discussion Number 14 NWS National Hurricane Center Miami FL AL092022 1100 AM EDT Mon Sep 26 2022 The satellite presentation of Ian has improved this morning. Deep convection has increased within the inner core during the past several hours, with an expanding central dense overcast noted in recent satellite imagery. The inner core structure continues to take shape in radar data, although the eyewall still has a banded appearance and remains open on the west side. Dropsonde data from the NOAA and Air Force Hurricane Hunter aircraft indicate that the minimum pressure has gradually fallen to about 980 mb, and the initial intensity is raised slightly to 70 kt for this advisory. The intensity of Ian has increased by 30 kt during the past 18 h. Further rapid intensification (RI) is expected during the next 24-36 h as Ian crosses the high oceanic heat content of the northwestern Caribbean Sea within a very low vertical wind shear (VWS) environment. The latest SHIPS-RI probabilities continue to highlight the high likelihood of this scenario, with a 73 percent chance of a 35-kt wind speed increase in 24 h and a 79 percent chance of a 45-kt increase in 36 h. The NHC intensity forecast is similar to the previous one, and it shows Ian becoming a major hurricane by the time it reaches western Cuba. Ian is forecast to reach its peak intensity in 36 h over the southeastern Gulf of Mexico. Then, increasing southwesterly shear by 36-48 h is expected to bring an end to the intensification phase. The combination of strong VWS and drier mid-level air will induce weakening thereafter, but Ian is expected to remain at or near major hurricane strength as it passes near the west-central coast of Florida on Wednesday and Thursday. Ian continues to move northwestward at 325/11 kt. A turn toward the north-northwest and north is expected during the next day or so as the hurricane moves around the western extent of a mid-level ridge. Then, an upper-level trough over the eastern U.S. should cause Ian to turn more north-northeastward through Thursday. This track brings the center of Ian close to the west-central coast of Florida during the middle of the week. An even greater concern is the slower forward motion that is forecast during this period, as the upper trough passes north and east of Ian and the steering currents weaken. This would likely prolong the storm surge, wind, and rainfall impacts along the affected portions of the west coast of Florida, although the roughly shore-parallel track still makes it difficult to pinpoint exactly what locations will experience the most severe impacts. The track guidance has come into better agreement during the first 72 h of the forecast period, and only a minor eastward adjustment was made to the NHC track forecast in line with the multi-model consensus aids. The aircraft data indicate that the 34-kt wind radii in the northeastern quadrant were 20-30 n mi larger than previously estimated, and this has been reflected in the latest forecast. Based on these changes, Tropical Storm Watches have been issued for the middle Florida Keys and extended southward along the southwestern 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. Life-threatening storm surge is possible along much of the Florida west coast, 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 possible in the hurricane watch area in west-central Florida beginning Wednesday morning with tropical storm conditions possible by late Tuesday. Residents in this area should ensure that they have their hurricane plan in place. 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 26/1500Z 19.1N 82.7W 70 KT 80 MPH 12H 27/0000Z 20.7N 83.5W 90 KT 105 MPH 24H 27/1200Z 22.7N 84.0W 105 KT 120 MPH 36H 28/0000Z 24.5N 84.0W 120 KT 140 MPH 48H 28/1200Z 26.1N 83.8W 120 KT 140 MPH 60H 29/0000Z 27.2N 83.5W 105 KT 120 MPH 72H 29/1200Z 28.0N 83.2W 90 KT 105 MPH 96H 30/1200Z 29.8N 82.9W 55 KT 65 MPH...INLAND 120H 01/1200Z 32.8N 82.6W 30 KT 35 MPH...INLAND $$ Forecaster Reinhart |
