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Tropical Storm Alvin Forecast Discussion Number 6
2019-06-27 04:32:29| National Hurricane Center (East Pacific)
Issued at 900 PM MDT Wed Jun 26 2019 000 WTPZ41 KNHC 270232 TCDEP1 Tropical Storm Alvin Discussion Number 6 NWS National Hurricane Center Miami FL EP012019 900 PM MDT Wed Jun 26 2019 Alvin's presentation on satellite images consists of a well-defined CDO with very cold cloud tops near/over the center, with very limited banding features. Upper-level outflow is fairly distinct over the western semicircle of the system. The current intensity estimate is boosted slightly, to 45 kt, based on Dvorak CI numbers from both TAFB and SAB. Alvin is likely to strengthen some more during the next 12 to 24 hours since it should be moving over sufficiently warm waters, within low vertical shear, and in a modestly moist air mass for the next day or so. Beyond 24 hours, cooling SSTs and gradually increasing shear should cause a weakening trend to commence. All of the models call for rapid weakening in 2 to 3 days, and the cyclone should degenerate into a remnant low by Saturday. The official intensity forecast is a little below the latest model consensus. Recent center fixes indicate that there is no longer a southward component of motion, and the initial motion estimate is now westward or 270/11 kt. There have been no significant changes to the general track prediction philosophy. Over the forecast period, the cyclone is expected to move along the southwestern periphery of a mid-level ridge extending westward from northwestern Mexico. Most of the track guidance has shifted a little northward on this cycle, and the new official forecast is slightly north of the previous one, but a little south of the simple and corrected dynamical consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 14.4N 111.3W 45 KT 50 MPH 12H 27/1200Z 15.0N 112.9W 50 KT 60 MPH 24H 28/0000Z 16.0N 115.1W 55 KT 65 MPH 36H 28/1200Z 17.0N 117.3W 50 KT 60 MPH 48H 29/0000Z 18.0N 119.2W 40 KT 45 MPH 72H 30/0000Z 19.3N 122.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 01/0000Z...DISSIPATED $$ Forecaster Pasch
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