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Tropical Storm GONZALO


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TROPICAL STORM GONZALO DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082014
1100 AM AST MON OCT 13 2014

An Air Force Reserve reconnaissance aircraft investigating Gonzalo
this morning found 850 mb maximum flight-level winds of 64 kt along
with reliable SFMR surface winds near 55 kt in the northeastern
quadrant, plus a central pressure of 992 mb. In addition, the
Antigua-Barbuda Meteorological Service recently reported a sustained
wind of 58 kt and a gust to 76 kt. Based on these data, the
intensity has been increased to 55 kt. Reports from the aircraft
radar and Antigua-Barbuda also indicate the center of Gonzalo passed
over Antigua between 1300-1400 UTC.

The initial motion estimate is 290/9 kt. Gonzalo is expected to
continue to move west-northwestward today, and turn toward the
northwest after 24 hours when the cyclone clears the northern Lesser
Antilles. After that, the mid-level ridge to the north of Gonzalo is
expected to break down as a strong mid-latitude trough moving off of
the U.S. east and southeast coasts approaches the area north of
Puerto Rico and Hispaniola in about 72 hours. The weakening ridge
will allow Gonzalo to move slowly northward, and then turn toward
the northeast and accelerate on Days 4 and 5. The latest NHC model
guidance appears to have stabilized and has no longer made any
eastward shifts, so the official forecast track is just an update of
the previous advisory track, which lies close to a blend of the GFEX
and TVCN consensus models.

The satellite presentation of Gonzalo has continued to improve, and
radar data from Guadeloupe indicates that a small but intense vortex
may have passed over Antigua earlier this morning. Overall, the
improvement in the horizontal and vertical structure of Gonzalo the
past several hours, along with weak vertical wind shear and SSTs
greater than 29C, should allow for at least steady strengthening of
the cyclone through the next 96 hours. By 120 hours, southwesterly
wind shear of around 20 kt is expected to affect Gonzalo, which
should induce a slow weakening trend. The NHC intensity forecast is
similar to the previous forecast and the SHIPS intensity model.

Gonzalo is forecast to be reaching hurricane strength by the time it
passes near the British Virgin Islands, and so a hurricane warning
is in effect there.  Although hurricane conditions are not currently
expected in the U.S. Virgin Islands, only a slight deviation to the
left of the forecast track, or a more rapid strengthening of the
storm, would result in the need to extend the hurricane warning into
those areas. Interests in the hurricane watch area are reminded that
the watch means that hurricane conditions are possible...and in this
case within 24 hours.

FORECAST POSITIONS AND MAX WINDS

INIT  13/1500Z 17.2N  61.9W   55 KT  65 MPH
 12H  14/0000Z 18.0N  63.3W   60 KT  70 MPH
 24H  14/1200Z 19.4N  65.0W   70 KT  80 MPH
 36H  15/0000Z 20.8N  66.4W   75 KT  85 MPH
 48H  15/1200Z 22.4N  67.5W   80 KT  90 MPH
 72H  16/1200Z 24.8N  68.0W   90 KT 105 MPH
 96H  17/1200Z 27.4N  66.9W   95 KT 110 MPH
120H  18/1200Z 31.7N  64.0W   90 KT 105 MPH

$$
Forecaster Stewart

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