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Tropical Storm GONZALO (Text)

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TROPICAL STORM GONZALO DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082014
500 AM AST MON OCT 13 2014

The satellite presentation of Gonzalo has gradually improved
overnight with increased banding features seen in both infrared
satellite images and Guadeloupe radar.  The small inner core has
also become a little better defined in the radar imagery.  Dvorak
data T-numbers from SAB and TAFB are 3.0 and 3.5, respectively, and
the initial wind speed has been increased to 50 kt. An Air Force
Reserve Hurricane Hunter aircraft is scheduled to investigate the
cyclone in a few hours, which should provide a better assessment of
Gonzalo's intensity and size.  Although some mid-level dry air is
noted to the west of the cyclone, low shear and warm water should
favor strengthening during the next several days.  The NHC intensity
forecast calls for steady intensification and Gonzalo is forecast to
become a hurricane in 24 to 36 hours. The updated intensity forecast
is close to the SHIPS model and is very similar to the previous
advisory.

The initial motion estimate is 280/9 kt.  Gonzalo is forecast to
turn west-northwestward, then northwestward during the next day or
so, while it moves around the southwestern periphery of a mid-level
ridge over the central subtropical Atlantic.  Most of the track
guidance has again shifted slightly eastward during the first 48
hours, and the NHC forecast track has been nudged in that direction.
The NHC forecast is along the southern edge of the guidance envelope
during the first couple of days and is close to the GFS and ECMWF
models.  After that time, Gonzalo is forecast to turn northward
then north-northeastward ahead of a deep-layer trough that
approaches the east coast of the United States in about 4 days.
Although the track guidance is in general agreement on this
scenario, there remains large differences in the forward speed
of the cyclone later in the period.  The GFS, UKMET, and HWRF
showing more north-northeastward acceleration than the ECMWF.  The
updated NHC track forecast is near the GFS/ECMWF consensus, which
is faster than the previous advisory.




FORECAST POSITIONS AND MAX WINDS

INIT  13/0900Z 16.8N  60.9W   50 KT  60 MPH
 12H  13/1800Z 17.4N  62.5W   55 KT  65 MPH
 24H  14/0600Z 18.6N  64.3W   60 KT  70 MPH
 36H  14/1800Z 20.2N  65.8W   70 KT  80 MPH
 48H  15/0600Z 21.5N  67.0W   75 KT  85 MPH
 72H  16/0600Z 23.8N  68.1W   85 KT 100 MPH
 96H  17/0600Z 26.0N  67.5W   95 KT 110 MPH
120H  18/0600Z 29.0N  65.5W   90 KT 105 MPH

$$
Forecaster Brown

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