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| #1107693 (Received by flhurricane at: 11:00 PM 17.Sep.2022) TCDAT2 Tropical Storm Fiona Discussion Number 15 NWS National Hurricane Center Miami FL AL072022 1100 PM AST Sat Sep 17 2022 Satellite imagery and Doppler radar data from San Juan indicate that Fiona is gradually becoming better organized, with the radar showing increasing banding near the center and a possible decrease in the radius of maximum winds. However, this has not yet resulted in any increase in intensity, with the radar winds and data from an Air Force Reserve Hurricane Hunter aircraft suggesting that the maximum sustained winds remain near 50 kt. The aircraft has reported that the central pressure has fallen to 997 mb. Fiona`s motion has been a bit erratic over the past few hours. However, the longer-term motion is a somewhat uncertain 285/7 kt. A turn toward the northwest is expected in about 12 h, with a general northwestward motion continuing through about 48 h as Fiona is steered by the subtropical ridge to the northeast. After that, the cyclone is expected to move slowly northward through a break in the ridge caused by a mid- to upper-level trough over the Florida Peninsula and the adjacent Atlantic. By the end of the forecast period, a north-northeastward motion at a faster forward speed is expected as Fiona reaches the southern edge of the mid-latitude westerlies. The new forecast track is similar to the previous track and to the consensus models, with the center forecast to move near the southwestern portion of Puerto Rico and the northern coast of the Dominican Republic before passing east of the Turks and Caicos Islands. While the vertical wind shear has diminished since yesterday, Fiona remains in an environment of moderate southwesterly shear, and the model guidance suggests that this is likely to persist through the forecast period. This will limit the intensification, although the storm will pass over warm sea surface temperatures and move into a more moist environment. The new intensity forecast calls for Fiona to reach hurricane strength in about 24 h as it passes near Puerto Rico. After that, development could be interrupted by close proximity to the Dominican Republic. More earnest strengthening appears likely when Fiona moves away from land after 48 h, and the intensity forecast again calls for a peak intensity of 95 kt. It should be noted that the intensity guidance has a large amount of spread, and there are models both stronger and weaker than the official forecast. Key Messages: 1. Hurricane conditions are expected across portions of Puerto Rico on Sunday, and are expected in portions of the Dominican Republic Sunday night and Monday. Hurricane conditions 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 tonight. Tropical storm conditions will reach the Dominican Republic by late Sunday. 2. Heavy rains from Fiona will continue to spread west across the British and U.S. Virgin Islands and Puerto Rico tonight, 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 portions of the eastern 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 18/0300Z 16.6N 64.9W 50 KT 60 MPH 12H 18/1200Z 17.2N 66.0W 60 KT 70 MPH 24H 19/0000Z 18.1N 67.3W 65 KT 75 MPH 36H 19/1200Z 19.1N 68.5W 65 KT 75 MPH 48H 20/0000Z 20.3N 69.4W 70 KT 80 MPH 60H 20/1200Z 21.6N 70.2W 75 KT 85 MPH 72H 21/0000Z 23.0N 70.5W 80 KT 90 MPH 96H 22/0000Z 25.5N 70.5W 90 KT 105 MPH 120H 23/0000Z 31.0N 67.5W 95 KT 110 MPH $$ Forecaster Beven |
