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| #1109424 (Received by flhurricane at: 7:00 AM 28.Sep.2022) TCDAT4 Hurricane Ian Special Discussion Number 23 NWS National Hurricane Center Miami FL AL092022 700 AM EDT Wed Sep 28 2022 This special advisory is being issued to update Ian's current and forecast intensity. Recent NOAA and Air Force Reserve Hurricane Hunter flight-level winds are as high as 160 kt, with SFMR data around 135 kt, with a central pressure down to 937 mb. This supports a current intensity of 135 kt. The forecast intensity is raised to 135 kt at landfall, and we are now forecasting a catastrophic storm surge of 12 to 16 ft from Englewood to Bonita Beach, Florida. No other significant changes were made to the forecast. Previous discussion -- Ian completed an eyewall replacement cycle during the overnight hours, and very recent data from an Air Force Reserve Hurricane Hunter aircraft indicate that the hurricane has reached category 4 intensity. The plane reported that the central pressure has fallen to 942 mb, down about 10 mb from around midnight. The plane measured a peak 700-mb flight-level wind of 141 kt, and an SFMR wind of 109 kt. A blend of the 700-mb reduced wind and the SFMR yields an initial intensity of 120 kt. Although there is some moderate shear over the hurricane, this is not likely to affect Ian very much due to its large size. Some fluctuations in intensity are possible before the center reaches the coast later today, but Ian is expected to reach the coast as an extremely dangerous category 4 hurricane. Weakening is expected while Ian moves over the Florida peninsula. Ian has jogged a little to the left this morning, but the longer-term motion remains north-northeastward or 015 degrees at 9 kt. The hurricane should continue moving north-northeastward through Thursday between the western side of a subtropical ridge and a broad trough over the eastern United States. This motion is expected to bring the center of Ian onshore along the west coast of Florida later today, and over central Florida tonight and Thursday. A shortwave trough that is forecast to move southward toward the northwestern Gulf in about 24 to 36 hours is expected to sharpen the trough over the eastern U.S. causing Ian to turn northward along coast of northeastern Florida and Georgia Thursday night and Friday. The model envelope did not change much this cycle, and very little cross-track adjustments were needed to the official forecast. The GFS and ECWMF are noticeably slower than the remainder of the dynamical models, and the updated NHC track forecast is a little slower than the previous advisory and slightly slower than the TVCA consensus aid out of respect for those models. Key Messages: 1. Catastrophic storm surge inundation of 12 to 16 feet above ground level along with destructive waves are expected somewhere along the southwest Florida coastline from Englewood to Bonita Beach, including Charlotte Harbor. Residents in these areas should urgently follow any evacuation orders in effect. 2. Catastrophic wind damage is expected along the southwestern coast of Florida beginning in the next few hours where the core of Ian makes landfall. Preparations to protect life and property should be urgently rushed to completion. 3. Heavy rainfall will spread across the Florida peninsula through Thursday and reach portions of the Southeast U.S. later this week and this weekend. Widespread, life-threatening catastrophic flooding is expected across portions of central Florida with considerable flooding in southern Florida, northern Florida, southeastern Georgia and coastal South Carolina. Widespread, prolonged major and record river flooding expected across central Florida. FORECAST POSITIONS AND MAX WINDS INIT 28/1100Z 25.9N 82.8W 135 KT 155 MPH 12H 28/1800Z 26.7N 82.4W 135 KT 155 MPH 24H 29/0600Z 27.7N 81.7W 80 KT 90 MPH...INLAND 36H 29/1800Z 28.7N 81.1W 50 KT 60 MPH...INLAND 48H 30/0600Z 29.8N 80.7W 45 KT 50 MPH...OVER WATER 60H 30/1800Z 31.6N 80.8W 45 KT 50 MPH 72H 01/0600Z 33.6N 81.4W 30 KT 35 MPH...INLAND 96H 02/0600Z 36.1N 82.1W 25 KT 30 MPH...POST-TROP/INLAND 120H 03/0600Z...DISSIPATED $$ Forecaster Blake |
