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| #1108957 (Received by flhurricane at: 11:03 PM 25.Sep.2022) TCDAT4 Tropical Storm Ian Discussion Number 12 NWS National Hurricane Center Miami FL AL092022 1100 PM EDT Sun Sep 25 2022 The storm has become better organized-looking on satellite imagery, with strengthening central convection and developing banding features. Upper-level anticyclonic outflow also appears to be increasing over the system. Flight-level winds, Doppler radar velocities, and dropsonde data from a NOAA Hurricane Hunter aircraft indicate that Ian's intensity is now near 55 kt. Ian has turned toward the northwest and the initial motion estimate is now 315/11 kt. During the next 48 hours, the tropical cyclone is expected to turn toward the north as it moves along the western side of a mid-level high pressure area. Later in the forecast period, a broad mid-tropospheric trough over the eastern United States is likely to induce a slightly east of northward motion. However, around 4 days, the steering currents are forecast to weaken as the trough moves to the east of Ian's longitude. Some of the guidance model tracks such as that from the GFS have, again, shifted to the east, mainly after 48 hours. The official track forecast has been shifted somewhat to the east of the previous one and is mainly a blend of the latest ECMWF and GFS predictions. It should again be stressed that there is still significant uncertainty in the track of Ian, especially in the 3-5 day time frame. Users should not focus on the details of the track forecast at longer time ranges. Observations from the aircraft indicate that the tropical cyclone is developing an inner core, so significant intensification is likely to occur during the next couple of days. The SHIPS Rapid Intensification Index indicate a fairly high chance for rapid strengthening during the next 24 to 36 hours, and the official forecast reflects this likelihood, calling for Ian to become a major hurricane over the southeastern Gulf of Mexico. Key Messages: 1. Ian is expected to produce heavy rainfall and instances of flash flooding and possible mudslides in areas of higher terrain, particularly over Jamaica and Cuba. Considerable flooding impacts are possible later this week in west central Florida. Additional flash and urban flooding, and flooding on rivers across the Florida Peninsula and parts of the Southeast cannot be ruled out for later this week. 2. Life-threatening storm surge and hurricane-force winds are expected in portions of western Cuba beginning late Monday, and Ian is forecast to be at or near major hurricane strength when it is near western Cuba. Efforts to protect life and property should be rushed to completion. 3. Ian is expected to be a major hurricane in the eastern Gulf of Mexico during the middle of this week, but uncertainty in the track and intensity forecasts remains higher than usual. Regardless of Ian’s exact track and intensity, there is a risk of dangerous storm surge, hurricane-force winds, and heavy rainfall along the west coast of Florida and the Florida Panhandle by the middle of this week, and residents in Florida should ensure they have their hurricane plan in place. Follow any advice given by local officials and closely monitor updates to the forecast. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 17.3N 81.4W 55 KT 65 MPH 12H 26/1200Z 18.7N 82.3W 65 KT 75 MPH 24H 27/0000Z 20.8N 83.5W 85 KT 100 MPH 36H 27/1200Z 22.7N 84.0W 100 KT 115 MPH 48H 28/0000Z 24.7N 84.1W 105 KT 120 MPH 60H 28/1200Z 26.2N 83.8W 115 KT 130 MPH 72H 29/0000Z 27.6N 83.5W 105 KT 120 MPH 96H 30/0000Z 29.0N 83.2W 80 KT 90 MPH 120H 01/0000Z 32.0N 82.5W 40 KT 45 MPH...INLAND $$ Forecaster Pasch |
