000
WTNT43 KNHC 160258
TCDAT3

HURRICANE GONZALO DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082014
1100 PM AST WED OCT 15 2014

Although satellite images have recently shown increased
organization, aircraft data suggest that Gonzalo has actually
slightly weakened.  An Air Force Reserve Hurricane Hunter aircraft
measured peak flight-level winds of 118 kt and a peak SFMR value of
99 kt.  These data support an initial intensity of 105 kt.

The plane did report that the concentric eyewall cycle has finished,
suggesting that the weakening trend is probably over.  Little
change in strength is shown for the next 24 hours since the shear
expected to be weak or moderate while the hurricane traverses warm
waters. Gradual weakening is shown after that time due to the
cyclone moving across cooler waters, some of which were upwelled by
the recent passage of Fay near Bermuda.  The official NHC forecast
is a little lower than the previous one, although is on the higher
side of the guidance during the first 36 hours.  Transition to a
post-tropical cyclone is expected in about 72 hours with most of
the models showing Gonzalo becoming a large warm-seclusion low.

Gonzalo is turning northward as it feels the effects of a strong
trough over the eastern United States.  There is good agreement on
the cyclone moving toward the north-northeast tomorrow and northeast
on Friday, accelerating as it is steered by the trough.  The NHC
forecast virtually unchanged over the first couple of days of the
prediction, with most of the models showing Gonzalo near Bermuda in
a little over 36 hours.  At longer range, the extratropical cyclone
should move more to the east-northeast as it moves within the fast
mid-latitude flow to the north of a central Atlantic ridge.  Only
small changes were made to the previous forecast, which ends up
being slightly slower at days 4 and 5.



FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 24.6N  68.7W  105 KT 120 MPH
 12H  16/1200Z 25.8N  68.7W  105 KT 120 MPH
 24H  17/0000Z 28.1N  68.0W  105 KT 120 MPH
 36H  17/1200Z 30.7N  66.6W  100 KT 115 MPH
 48H  18/0000Z 33.8N  64.8W   90 KT 105 MPH
 72H  19/0000Z 43.8N  57.4W   80 KT  90 MPH...POST-TROPICAL
 96H  20/0000Z 52.0N  37.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  21/0000Z 55.0N  17.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Blake