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| #1107648 (Received by flhurricane at: 5:54 PM 17.Sep.2022) TCDAT2 Tropical Storm Fiona Discussion Number 14 NWS National Hurricane Center Miami FL AL072022 500 PM AST Sat Sep 17 2022 After going through a bit of a re-organization this morning, Fiona`s structure appears to be improving again. Visible satellite images show an elongated band of deep convection wrapping around the center from north to east to southwest, and WSR-88D Doppler radar from San Juan, Puerto Rico, suggests that a better-defined center of circulation has developed. A 1707 UTC AMSR-2 microwave pass also shows that a mid-level eye feature may be developing. The last Air Force Reserve reconnaissance mission from a few hours ago found that the central pressure had fallen back down to 1002 mb, but maximum winds still appeared to be around 50 kt. The next reconnaissance mission is scheduled for this evening. Fiona`s motion today has been discontinuous due to the storm`s center re-formation, but the smoothed longer-term motion is now west-northwestward, or 285/8 kt. This general motion is expected to continue through tonight, with Fiona expected to turn northwestward on Sunday as it begins to move around the western periphery of the subtropical ridge. A turn toward the north-northwest is expected by Monday night, followed by a northward and north-northeastward acceleration over the western Atlantic by Thursday. In general, the new NHC forecast is close to the TVCN and HCCA consensus aids, in the middle of the guidance envelope. This prediction is a little bit north of this morning`s forecast during the first 24 to 36 hours, mainly accounting for Fiona`s adjusted initial position. After 36 hours, the track forecast is not too different from earlier. Since the new track forecast has the center of Fiona reaching Puerto Rico in about 24 hours, the window for strengthening is less than it was earlier today. However, the NHC intensity forecast is near the IVCN and HCCA consensus aids and suggests that Fiona will be at or near hurricane intensity before moving across Puerto Rico on Sunday. If the center does cross Puerto Rico, that could halt intensification, or cause some slight weakening, but Fiona is expected to go through a more significant strengthening phase once it`s over the western Atlantic. The forecast shows Fiona just below major hurricane intensity by day 5, although it should be mentioned that this prediction is slightly below the consensus aids. Key Messages: 1. Hurricane conditions are expected across portions of Puerto Rico on Sunday, and are possible across the U.S. Virgin Islands tonight. Tropical storm conditions are now spreading westward across the U.S. and British Virgin Islands and will spread across Puerto Rico this evening and tonight. Tropical storm conditions will reach the Dominican Republic by late Sunday. 2. Heavy rains from Fiona will spread west to the British and U.S. Virgin Islands and Puerto Rico today, the Dominican Republic Sunday, and the Turks and Caicos Monday night. These rainfall amounts are expected to produce life-threatening flash floods and urban flooding, along with mudslides in areas of higher terrain, especially across portions of Puerto Rico and the Dominican Republic. 3. Fiona is forecast to strengthen after moving away from Puerto Rico and past the Dominican Republic on Monday, and interests in the Turks and Caicos Islands and southeastern Bahamas should continue to monitor forecasts for the storm. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 16.7N 64.6W 50 KT 60 MPH 12H 18/0600Z 17.3N 65.5W 60 KT 70 MPH 24H 18/1800Z 18.1N 66.7W 65 KT 75 MPH...OVER PUERTO RICO 36H 19/0600Z 19.0N 68.0W 65 KT 75 MPH...OVER WATER 48H 19/1800Z 20.1N 69.0W 70 KT 80 MPH 60H 20/0600Z 21.4N 69.8W 75 KT 85 MPH 72H 20/1800Z 22.7N 70.5W 80 KT 90 MPH 96H 21/1800Z 25.4N 70.7W 90 KT 105 MPH 120H 22/1800Z 29.9N 68.8W 95 KT 110 MPH $$ Forecaster Berg |
