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Tropical Storm Alvin Forecast Discussion Number 5
2019-06-26 22:31:53| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Wed Jun 26 2019 295 WTPZ41 KNHC 262031 TCDEP1 Tropical Storm Alvin Discussion Number 5 NWS National Hurricane Center Miami FL EP012019 300 PM MDT Wed Jun 26 2019 Alvin is a small tropical storm as indicated by a recent scatterometer pass that showed tropical storm force winds extending only about 30 n mi from the center in the northern semicircle. This scatterometer data as well as an average of satellite intensity estimates from TAFB and SAB support an initial intensity of 40 kt. Alvin has continued to move south of due west throughout the day, and the initial motion estimate remains 260/12 kt. Through 24 hours, little change was made to the NHC forecast track, as the cyclone is expected to move westward and then west-northwestward around the southwestern periphery of a subtropical ridge through dissipation. The latest forecast track is on the southern edge of the guidance envelope through 36 hours, and has been shifted a little northward closer to the consensus aids from 48 to 72 hours. Although dry air has been trying to entrain into the storm's circulation today, deep convection continues to develop over the center. Some additional strengthening is still expected through 24 hours as the cyclone moves over warm SSTs in a low-shear and sufficiently moist environment. After 36 hours, the forecast track takes Alvin over progressively cooler waters and into a drier and higher-shear environment. This should result in steady weakening, with the cyclone likely becoming a remnant low by 72 hours, and dissipating by 96 hours. The new NHC forecast is near or a little below the latest dynamical and consensus intensity guidance. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 14.3N 110.3W 40 KT 45 MPH 12H 27/0600Z 14.3N 112.1W 45 KT 50 MPH 24H 27/1800Z 15.0N 114.3W 50 KT 60 MPH 36H 28/0600Z 16.0N 116.4W 50 KT 60 MPH 48H 28/1800Z 17.1N 118.5W 45 KT 50 MPH 72H 29/1800Z 18.3N 121.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 30/1800Z...DISSIPATED $$ Forecaster Latto/Brennan
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