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| #1019634 (Received by flhurricane at: 11:09 AM 02.Oct.2020) TCDAT5 Tropical Depression Twenty-Five Discussion Number 1 NWS National Hurricane Center Miami FL AL252020 1100 AM EDT Fri Oct 02 2020 Visible satellite images show that cloudiness and showers associated with the low pressure area over the northwestern Caribbean Sea have become significantly better organized since yesterday, with convective banding features becoming prominent. Moreover, low cloud motions suggest that a closed circulation has become better defined. Therefore, advisories are being initiated on Tropical Depression Twenty-Five at this time. The initial intensity estimate is 30 kt based on Dvorak T-numbers, but an Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the system later today to provide a better intensity estimate. Sea surface temperatures are very warm, near 30 deg C, and vertical shear should remain low for at least the next couple of days, so the cyclone is likely to become a tropical storm by the time it nears the Yucatan Peninsula tomorrow. The main impediment to strengthening over the next few days should be the interaction with land. Given the uncertainties about how far offshore the center will be over the next several days, the official intensity forecast is conservative. Since there is still a lot of scatter in the center fixes, the initial motion estimate, 315/8 kt, is rather uncertain. For the next couple of days, the system is expected to move northwestward to north-northwestward on the southwestern edge of a mid-level high pressure area. This would take the center near or over the northeastern Yucatan Peninsula. After about 48 hours, the steering currents are not well-defined and there is considerable spread in the track models. At this time, it appears the cyclone should move slowly westward over the latter part of the forecast period in response to weak ridging over the north-central Gulf of Mexico. The official forecast is near or a little north of the corrected and simple model consensus predictions. Tropical Storm Warnings and Watches have been issued for a portion of the Yucatan Peninsula. KEY MESSAGES: 1. The system is expected to produce heavy rainfall that could result in life-threatening flash flooding over portions of the Yucatan Peninsula, far western Cuba and well away from the center in the Mexican states of Campeche, Tabasco, and northern Chiapas. 2. The depression is forecast to become a tropical storm and bring tropical storm conditions to portions of the Yucatan Peninsula on Saturday, where a Tropical Storm Warning is in effect. FORECAST POSITIONS AND MAX WINDS INIT 02/1500Z 18.1N 84.7W 30 KT 35 MPH 12H 03/0000Z 18.9N 85.6W 30 KT 35 MPH 24H 03/1200Z 19.8N 86.6W 35 KT 40 MPH 36H 04/0000Z 20.6N 87.2W 40 KT 45 MPH...INLAND 48H 04/1200Z 21.4N 87.5W 40 KT 45 MPH...INLAND 60H 05/0000Z 22.0N 87.6W 40 KT 45 MPH 72H 05/1200Z 22.0N 88.2W 45 KT 50 MPH 96H 06/1200Z 21.5N 90.5W 45 KT 50 MPH 120H 07/1200Z 21.5N 92.5W 45 KT 50 MPH $$ Forecaster Pasch |