[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 082032
TCDAT3

Tropical Storm Gabrielle Discussion Number  22
NWS National Hurricane Center Miami FL       AL082019
500 PM AST Sun Sep 08 2019

The convective structure of Gabrielle now consists of a very well
defined curved band that envelops the center, which is evident by
recent microwave data as well as satellite imagery. An earlier
scatterometer pass partially sampled the eastern semicircle of the
cyclone and indicated the tropical storm force winds had expanded to
90 n mi from the center in the northeastern quadrant. The latest
subjective Dvorak intensity estimate from TAFB has increased to 55
kt, which will the initial intensity for this advisory.

Gabrielle will continue to move over warm SSTs and in a moderately
favorable atmospheric environment for the next 24 hours. Based on
these factors and the improved structure of the cyclone today, some
slight strengthening is expected into tonight. Although not
implicitly shown in the forecast, it is possible that Gabrielle may
reach hurricane intensity sometime tonight or early tomorrow. By
tomorrow afternoon, the cyclone will move over cooler waters and
southwesterly shear will increase, which should cause a weakening
trend to begin. By 48 hours, Gabrielle is expected to merge with a
cold front and become an extratropical cyclone. The official
forecast is essentially an update of the previous one, and is near
the corrected consensus HCCA.

The anticipated recurvature has begun and the initial motion is now
350/14 kt. Gabrielle will turn to the northeast by Monday as the
system rounds the western periphery of a mid-level ridge centered
near the Azores. Once Gabrielle turns northeastward, it will become
embedded in the increasing southwesterly flow ahead of the
approaching mid-latitude trough, which will accelerate the cyclone's
forward motion. The official forecast was nudged a little west from
the previous advisory due to a slight westward shift in the
tightly clustered track guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  08/2100Z 35.3N  49.4W   55 KT  65 MPH
 12H  09/0600Z 37.3N  48.7W   60 KT  70 MPH
 24H  09/1800Z 40.0N  46.3W   60 KT  70 MPH
 36H  10/0600Z 42.5N  42.4W   55 KT  65 MPH
 48H  10/1800Z 45.2N  37.1W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  11/1800Z 52.3N  21.9W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  12/1800Z...DISSIPATED

$$
Forecaster Latto
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