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Hurricane Katia Discussion Number   6
NWS National Hurricane Center Miami FL       AL132017
1000 PM CDT Wed Sep 06 2017

Satellite images indicate that Katia has a small symmetric central
dense overcast with very deep convection near the center.
Subjective and objective Dvorak estimates have risen since the past
advisory and, after accounting for the low bias earlier, support an
initial wind speed of 70 kt.  With wind shear forecast to drop while
the hurricane remains over very warm waters, it is puzzling to see
that most of the regional hurricane guidance is only showing a small
increase in wind speed. Although this area of the Gulf of Mexico is
known for significant upwelling, Katia is a rather small tropical
cyclone that shouldn't stir up as much cool water from below as most
hurricanes would. After considering the potential upwelling and the
extremely favorable upper-level environment, the intensity forecast
is raised from the previous one, but could be conservative since the
SHIPS RI index is showing roughly a 50 percent of rapid
intensification during the next 24 hours.

Katia is drifting east-southeastward, caught in a light steering
area between two ridges.  The hurricane should gradually turn
southwestward during the next 24 hours, then accelerate after that
time due to a strengthening ridge over the northwestern Gulf of
Mexico.  The official forecast is very similar to the previous one,
on the south side on the dynamical model consensus TVCN in the
direction of the corrected consensus.

Given the latest wind radii forecast, the government of Mexico has
extended the hurricane watch northward to Cabo Rojo.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 21.7N  94.8W   70 KT  80 MPH
 12H  07/1200Z 21.5N  94.6W   80 KT  90 MPH
 24H  08/0000Z 21.3N  94.8W   90 KT 105 MPH
 36H  08/1200Z 21.1N  95.4W   95 KT 110 MPH
 48H  09/0000Z 20.6N  96.4W   95 KT 110 MPH
 72H  10/0000Z 19.0N  98.5W   20 KT  25 MPH...POST-TROP/INLAND
 96H  11/0000Z...DISSIPATED

$$
Forecaster Blake

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