Hurricane GONZALO

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HURRICANE GONZALO DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082014
1100 PM AST MON OCT 13 2014

The eye of Gonzalo moved just north of St. Maarten and over Anguilla
earlier this evening. St. Maarten reported a peak 2-minute wind of
55 kt and a gust of 65 kt with a minimum pressure of 994 mb. Data
from the Hurricane Hunter aircraft earlier indicated peak 700-mb
flight-level winds of around 85 kt, which support an intensity of 75
kt for this advisory. This intensity is also supported by the latest
Dvorak classification of T4.5 from TAFB. The next Hurricane Hunter
aircraft will be investigating Gonzalo around 0600 UTC.

Gonzalo appears to be poised to intensify, perhaps rapidly, in the
next day or so. The inner-core features are quite distinct in
recent microwave imagery and a warm spot has recently developed in
infrared imagery with a more symmetric cloud pattern. Given these
trends and the overall favorable environment, the intensity
forecast has been adjusted upward and is close to the the SHIPS
model on the high end of the intensity guidance through the first 48
hours, showing Gonzalo becoming a major hurricane in about 36 hours.
As Gonzalo gains latitude later in the period, southwesterly shear
ahead of a mid-latitude trough and cooler SSTs should result in
gradual weakening.

The eye of Gonzalo is now evident in WSR-88D imagery from San Juan,
and the initial motion estimate is 315/10. Overall, the track
forecast reasoning remains unchanged, as the hurricane will
move northwestward into a weakness in the subtropical ridge and
then accelerate northward and northeastward ahead of a mid-latitude
trough moving off the east coast of the United States. The new NHC
track forecast has been shifted a little to the right in the first
48 hours due to the initial position and motion and an adjustment
and toward the latest multi-model consensus. Beyond that time, the
new NHC forecast is largely and update of the previous one and is
close to but a bit slower than a blend of the GFS and ECMWF models,
especially by day 5.

FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 18.7N  63.4W   75 KT  85 MPH
 12H  14/1200Z 19.8N  64.7W   85 KT 100 MPH
 24H  15/0000Z 21.5N  66.1W   95 KT 110 MPH
 36H  15/1200Z 23.1N  67.4W  100 KT 115 MPH
 48H  16/0000Z 24.5N  68.1W  105 KT 120 MPH
 72H  17/0000Z 27.3N  67.9W  100 KT 115 MPH
 96H  18/0000Z 31.5N  65.5W   95 KT 110 MPH
120H  19/0000Z 37.0N  61.0W   85 KT 100 MPH

$$
Forecaster Brennan

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