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Tropical Storm ALVIN


Tropical Storm Alvin Discussion Number  11
NWS National Hurricane Center Miami FL       EP012019
200 AM PDT Fri Jun 28 2019

Alvin's satellite presentation has begun to degrade overnight with
the overall cloud pattern becoming elongated from southwest to
northeast. Earlier ASCAT data indicated that the center was located
within the southwestern portion of the main convective mass,
suggesting that southwesterly shear has caused the system to become
less symmetric.  Subjective Dvorak T-numbers from SAB and TAFB have
started to decrease, and a blend of the various satellite intensity
estimates yields an initial wind speed of 60 kt for this advisory.
Increasing southwesterly shear and cooler waters ahead of the storm
are expected to cause rapid weakening during the next 24 to 36
hours.  Since Alvin is a small cyclone, it is likely to suffer
from the affects of the hostile environment more quickly.  As a
result, the NHC intensity forecast calls for a faster rate of
weakening than indicated by the statistical SHIPS/LGEM models and
is closest to the latest Florida State Superensemble.  The cyclone
is forecast to degenerate into a remnant low on Saturday and it
should dissipate shortly thereafter.

The initial motion estimate is 305/13 kt. The track forecast
philosophy remains the same as the previous advisory.  Alvin should
continue to move around the western periphery of a subtropical ridge
during the next couple of days, with the weakening cyclone turning
more westward and decelerating.  The latest NHC track forecast is
near the various consensus aids and is essentially an update of
the previous official forecast.


INIT  28/0900Z 18.0N 116.3W   60 KT  70 MPH
 12H  28/1800Z 19.2N 118.0W   55 KT  65 MPH
 24H  29/0600Z 20.3N 119.8W   40 KT  45 MPH
 36H  29/1800Z 20.9N 121.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  30/0600Z 21.3N 122.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  01/0600Z...DISSIPATED

Forecaster Brown