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Tropical Storm Alvin Forecast Discussion Number 9
2019-06-27 22:32:09| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Thu Jun 27 2019 000 WTPZ41 KNHC 272032 TCDEP1 Tropical Storm Alvin Discussion Number 9 NWS National Hurricane Center Miami FL EP012019 300 PM MDT Thu Jun 27 2019 A pair of timely ASCAT passes just before 1800 UTC indicate that Alvin has strengthened a little more. Multiple 45-50 kt wind vectors were present in the northwest quadrant of the cyclone in both passes. The intensity of the tropical storm has been increased to 55 kt since the ASCAT instrument is likely undersampling the strongest winds of this small tropical storm. Most of the intensity models indicate that Alvin has reached its peak intensity, however, the HWRF and GFS suggest that Alvin could still squeak out a little more intensification during the next 12 h or so. While I can't rule out that Alvin could get a little stronger tonight, its window for strengthening is likely closing soon. The cyclone's infrared cloud signature has already taken on a shear pattern, and GFS- and ECMWF-based SHIPS diagnostics suggest that the shear should steadily increase during the next 48 h. Furthermore, the tropical storm is quickly approaching cooler waters. Nearly all of the models show Alvin degenerating into a remnant low within about 48 h and dissipating soon thereafter, and the NHC forecast reflects this. The initial motion of Alvin is still 300/12 kt. No changes of significance were made to the NHC track forecast which continues to closely follow HCCA and TVCN. Alvin should continue on this general heading for another 24 hours or so, before gradually turning westward as it degenerates into a remnant low over the weekend. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 16.6N 114.2W 55 KT 65 MPH 12H 28/0600Z 17.7N 115.9W 55 KT 65 MPH 24H 28/1800Z 19.3N 118.0W 45 KT 50 MPH 36H 29/0600Z 20.3N 119.9W 35 KT 40 MPH 48H 29/1800Z 20.9N 121.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 30/1800Z...DISSIPATED $$ Forecaster Zelinsky
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