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| #1193522 (Received by flhurricane at: 5:06 PM 12.Aug.2024) TCDAT5 Tropical Storm Ernesto Discussion Number 5 NWS National Hurricane Center Miami FL AL052024 500 PM AST Mon Aug 12 2024 Satellite images and data from the Air Force Hurricane Hunters indicate that a center of circulation has now formed, and deep convection is gradually organizing in bands around that feature. A combination of flight-level wind and SFMR data from the aircraft support increasing the winds to 35 kt. Since the system meets the definition of a tropical cyclone and has winds of tropical storm force, it is now designated Tropical Storm Ernesto. Based on the latest satellite images and aircraft data, the center has formed about 30 n mi north of the previous track. This makes the initial motion uncertain, but our best estimate is 285/24 kt. This fast forward speed is due to a strong low- to mid-level ridge situated just north of the system over the subtropical Atlantic. A fast west-northwestward motion is expected to continue, taking the storm across the northern Leeward Islands overnight and near or over the Virgin Islands and Puerto Rico Tuesday afternoon or Tuesday night. After that time, a significant slowdown and a turn to the north over the Atlantic is expected as a deep-layer trough pushes off the U.S. east coast, causing the ridge to shift eastward. The NHC track forecast is a little to the right of the previous one in the short term and lies on the left edge of the guidance through Ernesto`s track across the Caribbean. This forecast is closer to the middle of the guidance envelope while it is over the western and central Atlantic. Since Ernesto now has a center and a slightly improved circulation, strengthening seems likely. However, the rate of intensification will likely be slow during the next day or two due to the system`s broad structure and ragged convective pattern. More significant strengthening is forecast after Ernesto exits the Caribbean, when nearly all of the environmental conditions appear conducive. The NHC intensity forecast is a little higher than the previous one in the short term, trending toward the latest consensus aids. Key Messages: 1. Ernesto is expected to bring tropical storm conditions to portions of the Leeward Islands late tonight and Tuesday and to the Virgin Islands and Puerto Rico by late Tuesday. Tropical Storm Warnings are in effect for this entire area. 2. Heavy rainfall may result in locally considerable flash flooding and mudslides in areas of the Leeward and Virgin Islands through Wednesday, and over Puerto Rico late Tuesday into Thursday. 3. It is too soon to know what impacts Ernesto could bring to Bermuda late this week, and interests there should monitor the progress of this system. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 16.0N 57.5W 35 KT 40 MPH 12H 13/0600Z 16.2N 60.3W 40 KT 45 MPH 24H 13/1800Z 16.9N 63.4W 45 KT 50 MPH 36H 14/0600Z 18.5N 65.6W 50 KT 60 MPH 48H 14/1800Z 20.9N 67.1W 60 KT 70 MPH 60H 15/0600Z 22.9N 67.8W 70 KT 80 MPH 72H 15/1800Z 25.0N 68.0W 80 KT 90 MPH 96H 16/1800Z 29.4N 66.0W 95 KT 110 MPH 120H 17/1800Z 32.5N 64.3W 95 KT 110 MPH $$ Forecaster Cangialosi |
