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Tropical Storm POLO (Text)

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TROPICAL STORM POLO DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP172014
200 PM PDT THU SEP 18 2014

An Air Force reconnaissance plane just traversed the core of Polo,
and although a dropsonde measured a pressure of 983 mb with 25 kt
winds in the center, neither the flight-level nor SFMR-winds in any
quadrant support keeping Polo at hurricane intensity. The
maximum winds have been lowered to 60 kt in this advisory. This
is also reflected in the cloud pattern, which has become a little
bit disrupted in the past few hours. Polo had the opportunity to
strengthen, but it appears that the northeasterly shear increased
earlier than anticipated, halting the intensification. Little
change in strength is expected for the next 12 hours or so, but
a gradual weakening trend is forecast to begin in 24 hours, as
indicated by most of the guidance.

There is no change in the forecast track, and as in previous runs,
most of the guidance maintains Polo moving toward the northwest or
west-northwest around the periphery of an amplifying mid-level ridge
centered over Mexico. On the forecast track, the cyclone will pass
well south of the southwestern coast of Mexico and well south of the
southern Baja California peninsula.  The confidence in the track
forecast is relatively high since both the multi-model consensus
TVCN and the average of the GFS and the ECMWF models, GFEX, are
keeping Polo well removed from land.  However, any unexpected
deviation to the right of the track could require the issuance of a
tropical storm watch for the southern portion of the Baja
California peninsula.

FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 17.8N 105.9W   60 KT  70 MPH
 12H  19/0600Z 18.5N 106.7W   60 KT  70 MPH
 24H  19/1800Z 19.2N 107.6W   55 KT  65 MPH
 36H  20/0600Z 20.0N 108.5W   50 KT  60 MPH
 48H  20/1800Z 20.8N 110.0W   45 KT  50 MPH
 72H  21/1800Z 21.5N 112.5W   40 KT  45 MPH
 96H  22/1800Z 22.0N 115.0W   30 KT  35 MPH
120H  23/1800Z 22.0N 117.0W   25 KT  30 MPH...POST-TROP/EXTRATROP

$$
Forecaster Avila

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