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Tropical Storm Alvin Discussion Number   8
NWS National Hurricane Center Miami FL       EP012019
900 AM MDT Thu Jun 27 2019

Recent microwave imagery indicates that Alvin's convective structure
has improved over the past several hours, and a 1057 UTC SSMI
overpass showed a closed ring of convection around the mid-level
center of the small tropical storm. However, the infrared
presentation of Alvin has not changed significantly since the last
advisory and satellite intensity estimates are also unchanged. The
initial intensity is therefore held at 50 kt, in deference to ASCAT
data from late last night.

The dynamical models (primarily the HWRF, HMON, and GFS) continue to
indicate that Alvin could strengthen during the next 12 to 24 hours
before it reaches much colder waters to the north. Once the tropical
storm reaches those waters in a day or so, it should quickly weaken,
likely becoming a remnant low around or just after 48 h. The NHC
intensity forecast has not been changed substantially since the
previous advisory and remains close to the intensity consensus aids.
It is worth noting that the small size of Alvin could make it
susceptible to short-term swings of intensity, up or down, and once
weakening begins it could occur even faster than currently
indicated.

The official track forecast has been nudged slightly northward, but
is otherwise unchanged. The initial motion estimate is 300/12 kt,
and Alvin is expected to continue to move west-northwestward or
westward at a similar forward speed for the next 24 to 36 hours.
After that time, the cyclone should turn toward the west as it
weakens and becomes steered by shallow easterly flow to the north
before it dissipates entirely. The NHC forecast closely follows the
HCCA and TVCN aids.

FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 15.8N 113.1W   50 KT  60 MPH
 12H  28/0000Z 16.9N 114.9W   55 KT  65 MPH
 24H  28/1200Z 18.5N 117.0W   50 KT  60 MPH
 36H  29/0000Z 19.7N 119.0W   35 KT  40 MPH
 48H  29/1200Z 20.5N 120.7W   30 KT  35 MPH
 72H  30/1200Z...DISSIPATED

$$
Forecaster Zelinsky

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