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| #1107731 (Received by flhurricane at: 5:09 AM 18.Sep.2022) TCDAT2 Tropical Storm Fiona Discussion Number 16 NWS National Hurricane Center Miami FL AL072022 500 AM AST Sun Sep 18 2022 Fiona has continued to show signs of better organization in Doppler radar data from San Juan this morning, and earlier data from an Air Force Hurricane Hunter aircraft indicate that the storm has indeed strengthened. The aircraft reported peak flight-level (700 mb) winds of 57 kt, along with several instances of SFMR winds greater than 50 kt and a peak of 57 kt in the northeastern quadrant of the storm. Also, a center dropsonde indicated that the minimum pressure had fallen a few millibars to 994 mb. Based on these data, the initial intensity is raised to 55 kt for this advisory. After a brief northward jog last night, the center of Fiona appears to have resumed a more west-northwestward heading (290/7 kt). The storm is expected to turn northwestward later today, which should bring the center of Fiona near or over the southwestern portion of Puerto Rico this afternoon and near the northern coast of the Dominican Republic early Monday. Then, a mid-level trough over the southwestern Atlantic is forecast to induce a weakness in the steering ridge early next week. This should enable Fiona to turn slowly northward by midweek while it passes near or to the east of the Turks and Caicos Islands. An acceleration to the north and north-northeast is forecast by late in the week as Fiona moves within the flow ahead of an amplifying mid- to upper-level trough. The models are tightly clustered throughout the forecast period and no major changes were made to the NHC track forecast, which still lies close to the consensus aids near the center of the guidance envelope. Moderate southwesterly to westerly shear appears likely to continue affecting Fiona during the next several days. However, very warm sea-surface temperatures and sufficient mid-level moisture are still expected to allow for some intensification as Fiona approaches Puerto Rico and the Dominican Republic. The NHC forecast calls for Fiona to become a hurricane later today before it moves near or over Puerto Rico. Once the cyclone moves away from land and reaches the southwestern Atlantic, more significant strengthening is forecast in agreement with the consensus of the intensity guidance. The latest NHC intensity forecast has been raised from 48 h through the end of the forecast period, but still lies slightly below the IVCN and HCCA aids. Fiona could reach major hurricane strength by late this week over the western Atlantic. Key Messages: 1. Hurricane conditions are expected across portions of Puerto Rico today, and are expected in portions of the Dominican Republic tonight and Monday. Tropical storm conditions are occurring across the U.S. and British Virgin Islands and are spreading westward across Puerto Rico. Tropical storm conditions will reach the Dominican Republic later today and tonight. 2. Heavy rains from Fiona will continue across Puerto Rico through tonight and occur over the Dominican Republic later today into Monday. These rainfall amounts will produce life-threatening flash floods and urban flooding across Puerto Rico and portions of the eastern Dominican Republic, along with mudslides and landslides in areas of higher terrain. 3. Fiona is forecast to strengthen after moving away from Puerto Rico and the Dominican Republic. Tropical storm conditions are possible in the Turks and Caicos Islands and the southeastern Bahamas by late Monday or early Tuesday, and a Tropical Storm Watch has been issued for these locations. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 17.1N 65.8W 55 KT 65 MPH 12H 18/1800Z 17.8N 66.9W 65 KT 75 MPH 24H 19/0600Z 18.7N 68.0W 65 KT 75 MPH 36H 19/1800Z 19.8N 69.0W 70 KT 80 MPH 48H 20/0600Z 21.2N 69.8W 80 KT 90 MPH 60H 20/1800Z 22.6N 70.5W 85 KT 100 MPH 72H 21/0600Z 23.9N 70.7W 90 KT 105 MPH 96H 22/0600Z 27.5N 70.0W 95 KT 110 MPH 120H 23/0600Z 33.0N 66.0W 95 KT 110 MPH $$ Forecaster Reinhart |
