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Tropical Storm Gabrielle Discussion Number 27
NWS National Hurricane Center Miami FL AL082019
1100 PM AST Mon Sep 09 2019
Gabrielle's convection has waned considerably since the previous
advisory, and the cloud pattern now has a disheveled appearance that
is becoming more reminiscent of an extratropical low pressure
system. However, a recent 2246Z ASCAT-A scatterometer pass indicated
that the tropical storm has maintained a very robust surface wind
field, with peak winds still at 45 kt and a radius of maximum winds
of 45-50 nmi.
The initial motion estimate is 055/21 kt, based primarily on passive
microwave and scatterometer satellite fixes. Gabrielle is now well
embedded in the high-latitude westerlies, and an additional increase
in forward speed toward the northeast or east-northeast is expected
over the next 2 days. By 72 hours, Gabrielle is forecast to
dissipate near the northern British Isles.
Gabrielle is currently located over sub-25 deg C sea-surface
temperatures and within a strong vertical wind shear regime of near
30 kt. With much colder water and stronger southwesterly shear ahead
of the cyclone, extratropical transition now appears likely to occur
within the next 12 hours. The intensity forecast is similar to the
previous advisory, and is a blend of the statistical SHIPS intensity
models, and the GFS and ECMWF dynamical model wind fields.
FORECAST POSITIONS AND MAX WINDS
INIT 10/0300Z 42.1N 43.1W 45 KT 50 MPH
12H 10/1200Z 44.0N 39.5W 45 KT 50 MPH...POST-TROP/EXTRATROP
24H 11/0000Z 46.6N 34.6W 40 KT 45 MPH...POST-TROP/EXTRATROP
36H 11/1200Z 50.1N 27.1W 35 KT 40 MPH...POST-TROP/EXTRATROP
48H 12/0000Z 54.0N 16.6W 30 KT 35 MPH...POST-TROP/EXTRATROP
72H 13/0000Z...DISSIPATED
$$
Forecaster Stewart
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