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| #1153132 (Received by flhurricane at: 4:42 PM 16.Sep.2023) TCDAT5 Tropical Depression Fifteen Discussion Number 6 NWS National Hurricane Center Miami FL AL152023 500 PM AST Sat Sep 16 2023 The tropical depression remains poorly organized this afternoon. However, visible satellite imagery continues to indicate a broad region of low- and mid-level rotation, and deep convection has increased somewhat in the northern semicircle of the disturbance. Subjective Dvorak estimates from SAB and TAFB remain steady at 25 kt and 35 kt, respectively. Based on the current structure and the various intensity estimates, the intensity is held at 30 kt for this advisory. The initial motion is estimated at 330/14 kt. This general motion is expected to continue for the next couple days as the depression moves along the southern periphery of a mid-level ridge. Consensus track guidance, as well as the global and regional hurricane models, are in general agreement during the early portion of the forecast period. Early next week, the track forecast uncertainty increases somewhat as the system will begin to interact with a deep-layer trough. This trough interaction is expected to induce a more poleward shift in the track and eventually recurve the system toward the northeast after 96 hours. The NHC track forecast is in agreement with the consensus aids, TVCN and HCCA, and slightly faster than the prior forecast. Environmental conditions remain favorable for intensification during the next several days, with low vertical wind shear and warm sea surface temperatures expected to persist along the forecast track. The timing of intensification will depend on how quickly the system is able to consolidate into a more compact structure. The current intensity forecast assumes that it will take 24-36 hours for this to happen, with the system expected to become a hurricane in 48 hours. The current forecast reaches 95 kt by 72 h, although the regional hurricane models HWRF and HAFS indicate that a major hurricane is not out of the question. ECMWF-SHIPS guidance continues to indicate the possibility of rapid intensification in the next 72 hours. By mid-week, as the system recurves to the northeast, it is expected to gradually weaken as southwesterly shear increases. The NHC forecast is in the middle of the guidance envelope and is similar to both the prior forecast and HCCA. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 20.8N 47.1W 30 KT 35 MPH 12H 17/0600Z 22.3N 48.2W 35 KT 40 MPH 24H 17/1800Z 24.2N 49.7W 45 KT 50 MPH 36H 18/0600Z 25.6N 51.1W 55 KT 65 MPH 48H 18/1800Z 26.9N 52.9W 65 KT 75 MPH 60H 19/0600Z 28.3N 54.8W 80 KT 90 MPH 72H 19/1800Z 30.0N 56.4W 95 KT 110 MPH 96H 20/1800Z 34.6N 57.3W 90 KT 105 MPH 120H 21/1800Z 39.6N 52.0W 80 KT 90 MPH $$ Forecaster Hogsett/Bucci |
