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