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| #1107259 (Received by flhurricane at: 10:51 PM 14.Sep.2022) TCDAT2 Tropical Storm Fiona Discussion Number 3 NWS National Hurricane Center Miami FL AL072022 1100 PM AST Wed Sep 14 2022 Although the system still appears ragged-looking in satellite images, a very recent ASCAT-B pass indicated that the tropical cyclone has strengthened. Maximum winds in the pass were around 45 kt and therefore, the initial intensity has been increased to that value. It should be noted that Fiona is an asymmetric storm with all of its thunderstorms and strong winds currently located on the system`s east side. The lopsided structure is due to moderate west-southwesterly vertical wind shear. Fiona continues to move westward at 12 kt. The steering pattern seems relatively straightforward. A low- to mid-level subtropical ridge situated over the central Atlantic should steer the system westward to west-northwestward during the next several days, taking the cyclone across the northern Leeward Islands by Friday night, near the Virgin Islands and Puerto Rico on Saturday, and near Hispaniola on Sunday and Monday. There will likely be a turn to the northwest by the end of the period when the system reaches the western periphery of the ridge. The models all show a similar theme, but there are notable speed differences with the ECMWF model faster than the remainder of the guidance. The NHC track forecast is quite similar to the previous one and near a consensus of the GFS and ECMWF models. Given the current tilted and asymmetric structure, continued influences of shear, and some dry air, any strengthening of the storm will likely be slow to occur during the next day or so. However, some of the models show Fiona moving into a less hostile environment in a couple of days, and it could have an opportunity to become a little stronger this weekend if it avoids the landmasses of Puerto Rico and Hispaniola. Given the uncertainty of the system`s future environment and potential land interaction, little change in strength is shown through most of the period. However, it should be noted that the intensity forecast is of low confidence given those complexities. Key Messages: 1. Tropical storm conditions are possible in portions of the northern Leeward Islands by Friday night, where a Tropical Storm Watch has been issued. 2. Heavy rains will begin to affect the northern Leeward Islands late Friday, spreading into the British and U.S. Virgin Islands and Puerto Rico over the weekend. This rainfall may produce isolated flash and urban flooding, along with isolated mudslides in areas of higher terrain. 3. Fiona is expected to move near the Virgin Islands, Puerto Rico, and Hispaniola this weekend and early next week, and Tropical Storm Watches will likely be issued for some of those areas on Thursday. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 16.7N 52.0W 45 KT 50 MPH 12H 15/1200Z 16.9N 53.8W 45 KT 50 MPH 24H 16/0000Z 17.1N 56.3W 50 KT 60 MPH 36H 16/1200Z 17.2N 58.9W 50 KT 60 MPH 48H 17/0000Z 17.3N 61.5W 50 KT 60 MPH 60H 17/1200Z 17.6N 63.8W 50 KT 60 MPH 72H 18/0000Z 17.8N 65.8W 50 KT 60 MPH 96H 19/0000Z 18.7N 68.6W 50 KT 60 MPH...INLAND 120H 20/0000Z 20.5N 70.6W 50 KT 60 MPH $$ Forecaster Cangialosi |
