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TROPICAL STORM FAY DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072014
1100 PM AST SUN OCT 12 2014

Fay's cloud pattern has rapidly deteriorated in organization since
this afternoon due to strong southwesterly vertical wind shear.
Microwave and last-light visible satellite imagery indicate that the
low-level center has become exposed to the southwest of a large mass
of very cold-topped convection. The same satellite data also
indicate that the center has become increasingly deformed, making
the initial position more uncertain than normal.  This uncertainty
has resulted in a large scatter in Dvorak intensity estimates. The
initial intensity is lowered to 55 kt, in agreement with the latest
Dvorak estimate from SAB, which was closest to the estimated center
position.

Even stronger west-southwesterly shear should affect Fay during the
next couple of days.  Meanwhile, much drier and more stable air
behind a cold front impinging on the storm from the northwest should
become entrained within Fay's circulation.  The combination of these
factors should lead to additional steady weakening, with global
models showing extratropical transition occurring in about 24 hours
(or perhaps sooner). The NHC intensity forecast is similar to the
previous one and in excellent agreement with the latest statistical-
dynamical model consensus.

The exposed center in the last few visible images was south of
previous estimates, and as a result the initial motion estimate is
now more sharply toward the east, or 080/21. Fay is expected to
continue racing eastward or east-southeastward at the base of a
potent shortwave trough moving through eastern Atlantic Canada and
the north Atlantic.  The NHC track forecast has been adjusted toward
the right of the previous one, based primarily on the new center
position and motion.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 34.1N  58.2W   55 KT  65 MPH
 12H  13/1200Z 34.4N  53.6W   50 KT  60 MPH
 24H  14/0000Z 33.9N  48.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  14/1200Z 33.4N  42.6W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  15/0000Z 33.0N  37.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  16/0000Z...DISSIPATED

$$
Forecaster Kimberlain

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