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Tropical Depression Fifteen-E Discussion Number 16
NWS National Hurricane Center Miami FL EP152017
800 AM PDT Fri Sep 15 2017
The depression has not really improved in organization, and there
still appears to be east-northeasterly shear displacing the deep
convection to the southwest of the center. The intensity remains 30
kt based on a blend of TAFB and SAB Dvorak estimates. The shear
over the depression is expected to decrease soon, reaching a minimum
in about 24-36 hours. Therefore, some strengthening appears
reasonable, and the depression may finally be able to become a
tropical storm on Saturday. An increase in easterly shear should
lead to weakening by the end of the forecast period. Some of the
models contained in ICON seem overblown on the cyclone's
intensification, so the NHC forecast is lower than the intensity
consensus and lies closest to the SHIPS model and HCCA.
The subtropical ridge to the north of the depression is expected to
push the cyclone slowly west-southwestward through 24 hours. After
that time, a break in the ridge will develop, which should cause
the cyclone to drift northward through days 3 and 4. A
re-establishment of the ridge by day 5 should impart a faster
westward motion by the end of the forecast period. Based on the
latest model guidance, the new NHC forecast is a little west of and
faster than the previous official forecast, especially on days 4
and 5.
FORECAST POSITIONS AND MAX WINDS
INIT 15/1500Z 15.9N 125.0W 30 KT 35 MPH
12H 16/0000Z 15.7N 125.4W 30 KT 35 MPH
24H 16/1200Z 15.5N 125.8W 35 KT 40 MPH
36H 17/0000Z 15.6N 126.1W 40 KT 45 MPH
48H 17/1200Z 16.1N 126.1W 40 KT 45 MPH
72H 18/1200Z 17.5N 126.0W 45 KT 50 MPH
96H 19/1200Z 18.2N 126.7W 40 KT 45 MPH
120H 20/1200Z 18.0N 128.7W 30 KT 35 MPH
$$
Forecaster Berg
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