Tropical Storm POLO
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TROPICAL STORM POLO DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
200 AM PDT FRI SEP 19 2014
Polo is showing a sheared cloud pattern this morning, with the
low-level center located near the northern or northeastern edge of
the convection. This is consistent with analyses of 20-25 kt of
easterly vertical wind shear impacting the cyclone. Satellite
intensity estimates are 55 kt from TAFB and 65 kt from SAB, and a
04Z ASCAT overpass showed 50-55 kt winds. Based on these, the
initial intensity remains 60 kt.
The initial motion is 315/7. Global models continue to forecast a
ridge of high pressure to develop westward from northern Mexico
during the next several days. This should cause the track of Polo
to gradually bend toward the west-northwest. By late in the forecast
period, the weakening cyclone should be drifting westward and
southwestward in the shallow low-level flow. The track guidance
shows little change from the previous advisory through 96 hours, and
then shows a more southwestward drift than forecast earlier. The
new official forecast follows this, and it is in best agreement with
the consensus model TVCE.
The large-scale models forecast the shear to continue through the
forecast period as Polo moves over progressively cooler sea surface
temperatures. This should lead to a gradual weakening as shown by
all of the intensity guidance. The new intensity forecast is
similar to that of the previous advisory, calling for Polo to
weaken to a tropical depression by 96 hours and to degenerate to a
remnant low by 120 hours.
FORECAST POSITIONS AND MAX WINDS
INIT 19/0900Z 18.9N 107.1W 60 KT 70 MPH
12H 19/1800Z 19.6N 107.9W 55 KT 65 MPH
24H 20/0600Z 20.4N 108.9W 55 KT 65 MPH
36H 20/1800Z 21.0N 110.1W 50 KT 60 MPH
48H 21/0600Z 21.7N 111.5W 45 KT 50 MPH
72H 22/0600Z 22.5N 114.0W 35 KT 40 MPH
96H 23/0600Z 22.5N 116.5W 30 KT 35 MPH
120H 24/0600Z 22.0N 117.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
Forecaster Beven
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