[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 091451
TCDAT3

Tropical Storm Gabrielle Discussion Number  25
NWS National Hurricane Center Miami FL       AL082019
Issued by the NWS Weather Prediction Center College Park MD
1100 AM AST Mon Sep 09 2019

Satellite images indicate that deep convection has increased
overnight and become more symmetric around the center of Gabrielle.
Still, ASCAT data show maximum winds of only about 40 kt,
suggestive that this convective burst hasn't changed the intensity
much.  The initial wind speed is set to 45 kt, near the TAFB
satellite estimate and a little above the ASCAT data to account for
undersampling.

Gabrielle has turned northeastward and picked up some speed.
The system is expected to move at an increasing pace in a similar
direction over the next few days as it is picked up by a
mid-latitude trough.  Model guidance is tightly clustered around
the previous NHC prediction, and no significant changes were made
to the prior NHC track forecast.

The storm has about a day over marginally warm waters before it
crosses the north wall of the Gulf Stream into much colder waters.
Gabrielle is forecast to transition into an extratropical low by
Tuesday due to an increase in shear and baroclinicity from an
approaching cold front.  The intensity forecast was reduced
slightly from the previous one and is in close agreement with a
blend of the GFS/ECMWF wind speed forecasts, which should best
handle this extratropical transition scenario.


FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 39.0N  47.3W   45 KT  50 MPH
 12H  10/0000Z 40.9N  44.7W   45 KT  50 MPH
 24H  10/1200Z 43.4N  40.2W   45 KT  50 MPH
 36H  11/0000Z 46.4N  34.7W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  11/1200Z 50.1N  26.9W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  12/1200Z 57.5N   5.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 96H  13/1200Z...DISSIPATED

$$
Forecaster Taylor/Blake
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