Tropical Storm POLO

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TROPICAL STORM POLO DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP172014
800 PM PDT TUE SEP 16 2014

Polo continues to gradually become better organized. The center is
located on the northern edge of an area of deep convection, and a
curved convective band has become better established in the western
semicircle. The initial intensity has been set to 45 kt based on
the latest Dvorak estimate from TAFB. The SHIPS model shows the
shear decreasing below 10 kt during the next 24 hours, which in
combination with very warm SSTs above 29C should allow for
intensification in the short term. In fact, the SHIPS RI index
shows a 66 percent chance of a 25-kt increase in the next 24 hours.
The official forecast has been adjusted upward in the short range,
and shows Polo becoming a hurricane by 24 hours. Easterly shear is
forecast to increase after that time, which should slow the pace
of strengthening. By the end of the period Polo will be moving over
cooler waters in a moderate shear environment, and gradual weakening
is expected. The new NHC intensity forecast is a a little above the
latest IVCN intensity consensus and is close to the SHIPS model
through the period.

A pair of timely SSMIS passes around 00 UTC were helpful in
establishing the initial position and the initial motion of 310/10.
The tropical cyclone will be steered northwestward for the next
several days by a mid-level ridge centered over northern Mexico. By
day 5, the cyclone should turn toward the west as the ridge builds
westward to its north. The new NHC track is a little left of the
previous one through 24 hours due to the initial position and
motion, but is otherwise an update of the previous track. Through
the period, the official forecast is close to the TVCE multi-model
consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 13.8N 101.3W   45 KT  50 MPH
 12H  17/1200Z 14.9N 102.4W   55 KT  65 MPH
 24H  18/0000Z 16.2N 103.8W   70 KT  80 MPH
 36H  18/1200Z 17.2N 105.2W   75 KT  85 MPH
 48H  19/0000Z 18.2N 106.6W   80 KT  90 MPH
 72H  20/0000Z 19.7N 108.7W   75 KT  85 MPH
 96H  21/0000Z 21.3N 111.0W   65 KT  75 MPH
120H  22/0000Z 22.0N 113.5W   50 KT  60 MPH

$$
Forecaster Brennan

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