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Tropical Storm Vicente Forecast Discussion Number 2
2018-10-19 22:37:00| National Hurricane Center (East Pacific)
Issued at 400 PM CDT Fri Oct 19 2018 000 WTPZ43 KNHC 192036 TCDEP3 Tropical Storm Vicente Discussion Number 2 NWS National Hurricane Center Miami FL EP232018 400 PM CDT Fri Oct 19 2018 Although tiny, the cyclone continues to display well-defined convective banding. The system's quick formation and small size make it difficult to have high confidence in its current intensity, and the various subjective and objective estimates range from T1.8/28 kt from the ADT to T3.0/45 kt from SAB. As a compromise, the intensity is set at 35 kt, which is closest to the TAFB estimate and the most recent SATCON number, and the depression is upgraded to Tropical Storm Vicente. As noted this morning, warm waters and low shear should induce further strengthening during the next 48 hours. On one hand, this intensification could be more than what is being indicated by the models, since small systems can have a tendency to gain strength quickly. On the other hand, Vicente will be interacting with a Gulf of Tehuantepec gap wind event during the next 48 hours, and the storm could end up ingesting some drier, more stable air into its circulation. The NHC intensity forecast favors the former scenario and is a little above the guidance envelope for the first 2-3 days. After day 3, an increase in shear, interaction with another possible tropical cyclone to the west, and possible interaction with land could all conspire to arrest the intensification trend, and weakening is expected by the end of the forecast period. It is also possible that Vicente could dissipate before the end of the 5-day period. This scenario is reminiscent of, and has similarities to, the interaction of Tropical Storm Ileana and Hurricane John back in early August. Vicente is moving very slowly northwestward, or 305/2 kt. The track models are indicating that the ongoing gap winds over the Gulf of Tehuantepec may have a greater influence of Vicente than previously thought, forcing the storm to turn west-southwestward in the next 24-48 hours. After 48 hours, Vicente should gradually enter the flow between mid-level ridging over Mexico and low pressure west of Mexico, causing it to turn back to the west and northwest on days 3 through 5. The new NHC track forecast is not too different from the morning forecast during that period, and it's closest to the paths shown by the GFS, HCCA, and FSSE guidance, which would bring the center close to the coast of Mexico later in the forecast period. There are considerable speed differences, however, and the NHC forecast splits the difference between the fast ECMWF solution and the slow GFS scenario. Even though Vicente should begin to slowly pull away from the coast tonight and on Saturday, heavy rainfall, with possible life-threatening flash flooding, is expected over portions of El Salvador, Guatemala, and southeastern Mexico during the next few days. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 13.3N 92.2W 35 KT 40 MPH 12H 20/0600Z 13.6N 93.3W 45 KT 50 MPH 24H 20/1800Z 13.3N 94.2W 50 KT 60 MPH 36H 21/0600Z 12.9N 95.2W 55 KT 65 MPH 48H 21/1800Z 12.7N 96.5W 55 KT 65 MPH 72H 22/1800Z 13.7N 99.8W 55 KT 65 MPH 96H 23/1800Z 16.5N 103.0W 55 KT 65 MPH 120H 24/1800Z 20.0N 106.0W 45 KT 50 MPH $$ Forecaster Berg
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