|
Show Selection: |
| #1109255 (Received by flhurricane at: 5:02 PM 27.Sep.2022) TCDAT4 Hurricane Ian Discussion Number 19 NWS National Hurricane Center Miami FL AL092022 500 PM EDT Tue Sep 27 2022 The pressure on the last Air Force Hurricane Hunter aircraft fix fell to about 952 mb, indicating that Ian is restrengthening over the southeastern Gulf of Mexico. The eye of Ian remains well-defined on visible imagery, although radar data from Key West suggest that an eyewall replacement could be in the initial stages. The initial wind speed is set to 105 kt, matching a blend of earlier SFMR and flight-level wind data. The plane data also showed that the area of hurricane-force winds is growing on the east side of the cyclone. Ian is moving east-of-due-north, or 010/9-kt, with occasional wobbles to the north-northeast. A track toward the north-northeast is expected for the next couple of days while it moves between a ridge over the Bahamas and a trough over the western Gulf of Mexico. There has been some model convergence this afternoon showing Ian remaining stronger and vertically deeper through landfall. This solution results in a faster track, again adjusted to the southeast, and the new forecast is moved in that direction. This new NHC track is close to the corrected model consensus and between the quicker ECMWF and slower GFS models. It should be emphasized that this track remains uncertain, with a typical spread in the steering features leading to big speed and track differences down the line, not to mention the oblique angle of approach to Florida. In a few days, more of the guidance is showing Ian interacting with a shortwave trough over the southeastern United States, causing the system to move back over the northwestern Atlantic in the longer range, before turning northwestward back over land. The day 3-5 track forecast is also shifted eastward, although significant re-strengthening is not expected at long range. The outflow pattern of the hurricane is beginning to be impinged upon in the southwestern quadrant, a sign that upper-level southwesterly flow is starting to affect the outer circulation. While the shear should increase up through landfall, it is just too close-to-call whether it starts to weaken Ian or not, or whether the larger system is able to resist the shear. Additionally, an eyewall replacement cycle could be in its initial phases, although predicting these structural changes is extremely difficult. The new forecast is near the last one, a little higher than the consensus. I should note that whether Ian comes ashore as category 4 hurricane or a large category 3 after an eyewall cycle, avoiding a large and destructive hurricane for Florida seems very unlikely, and residents should heed the advice of local emergency management officials. The new forecast necessitates a Hurricane Warning for portions of extreme southwestern Florida, and a Tropical Storm Warning for the rest of southeastern Florida that wasn't previously under a warning. Users are reminded to not focus on the exact track as some additional adjustments to the track are possible. Significant wind, storm surge, and rainfall hazards will extend far from the center. Key Messages: 1. Life-threatening storm surge is increasingly likely along the Florida west coast where a storm surge warning is in effect, with the highest risk from Naples to the Sarasota region. Residents in these areas should listen to advice given by local officials and follow any evacuation orders for your area. 2. Hurricane-force winds are expected in the hurricane warning area in southwest and west-central Florida beginning Wednesday morning with tropical storm conditions expected overnight. Devastating wind damage is expected near the core of Ian. Residents should rush all preparations to completion. 3. Heavy rainfall will affect most of the Florida Peninsula for the next several days, spreading to the rest of the Southeast U.S. by Thursday and Friday, likely causing flash, urban, and small stream flooding. Considerable flooding is expected with widespread, prolonged moderate to major river flooding expected across central Florida. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 24.0N 83.2W 105 KT 120 MPH 12H 28/0600Z 25.3N 82.9W 115 KT 130 MPH 24H 28/1800Z 26.6N 82.5W 115 KT 130 MPH 36H 29/0600Z 27.6N 82.0W 70 KT 80 MPH...INLAND 48H 29/1800Z 28.5N 81.5W 55 KT 65 MPH...INLAND 60H 30/0600Z 29.4N 81.2W 45 KT 50 MPH...INLAND 72H 30/1800Z 31.0N 81.1W 45 KT 50 MPH...OVER WATER 96H 01/1800Z 34.5N 82.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 120H 02/1800Z...DISSIPATED $$ Forecaster Blake |
