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000
WTPZ43 KNHC 260243
TCDEP3

TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182016
800 PM PDT SUN SEP 25 2016

The cloud pattern of the depression has not changed much during the last several hours. The center of the system is partially exposed on the west side of a convective band. Satellite images also show a pronounced dry slot to the west and northwest of the center. The Dvorak classifications remain T2.5/35 kt from TAFB and T1.5/25 kt from SAB, and based on these estimates, the initial wind speed is held at 30 kt.

Some slight strengthening is possible overnight or on Monday while the system remains over warm water and in an environment of light to moderate shear. After that time, the environment should become less conducive with southwesterly shear increasing to more than 20 kt in about 24 hours, which will likely end the opportunity for strengthening. The system is forecast to cross the 26-deg-C isotherm in 36 to 48 hours, and as a result, it should become a remnant low by day 3. The global models show the remnant low dissipating by the end of the forecast period, and that is reflected in the official forecast. The new intensity forecast is a little lower than the previous one and is in good agreement with the latest intensity model consensus.

The center of the depression has wobbled a bit to the west of the previous track, and the current motion estimate is 345/6 kt. A large cut-off mid- to upper-level low over northwestern Mexico is expected to drift southwestward during the next day or two. This should cause the system to turn north-northeastward to northeastward on Monday, and continue in that general direction through mid-week. Once the system becomes a shallow remnant low, a turn to the west-northwest is predicted, following the low-level trade wind flow. The NHC track forecast is not too different from the previous one, and is in best agreement with the GFS ensemble mean and a consensus of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0300Z 16.7N 120.1W 30 KT 35 MPH 12H 26/1200Z 17.2N 119.8W 35 KT 40 MPH 24H 27/0000Z 17.8N 119.4W 35 KT 40 MPH 36H 27/1200Z 18.7N 118.7W 35 KT 40 MPH 48H 28/0000Z 19.9N 118.0W 30 KT 35 MPH 72H 29/0000Z 22.6N 117.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 30/0000Z 24.6N 119.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/0000Z...DISSIPATED

$$ Forecaster Cangialosi

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