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Hurricane Gert Discussion Number  19
NWS National Hurricane Center Miami FL       AL082017
1100 AM AST Thu Aug 17 2017

The convective structure of Gert has rapidly deteriorated during
the morning hours due to very cold SSTs and vertical wind shear
exceeding 40 kt. The hurricane still has a little deep convection
in the northeast quadrant, but the low-level circulation appears to
have become somewhat elongated along a south-southwest,
north-northeast axis. Subjective Dvorak classifications from TAFB
and SAB have decreased, and the initial intensity has been decreased
accordingly, to 70 kt. Since there is a lack of recent
scatterometer or buoy observations near the center, the intensity
estimate is a little more uncertain than normal.

Gert continues to accelerate toward the northeast and the initial
motion estimate is 060/35 kt. Very little change has been made to
the track or intensity forecast. The cyclone is quickly becoming
extratropical, and the transition process should complete later
today. Gert should continue to steadily spin down while moving
quickly toward the northeast for the next day or so ahead of a large
extratropical low currently centered near the Gulf of St. Lawrence.
An interaction of the two cyclones should result in the eventual
absorption or dissipation of Gert shortly after 48 h. The track,
intensity, and wind radii forecasts have incorporated guidance from
NOAA's Ocean Prediction Center.

Swells from Gert should continue to affect the coast of the
northeastern U.S. and Atlantic Canada through tonight. These swells
are likely to produce dangerous surf and rip current conditions.
Please consult products from your local weather forecast office for
more information.


FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 43.2N  50.0W   70 KT  80 MPH
 12H  18/0000Z 46.0N  43.6W   55 KT  65 MPH...POST-TROP/EXTRATROP
 24H  18/1200Z 49.3N  37.4W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  19/0000Z 51.3N  35.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  19/1200Z 52.4N  34.3W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  20/1200Z...DISSIPATED

$$
Forecaster Zelinsky

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