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000
WTPZ43 KNHC 252032
TCDEP3

TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182016
200 PM PDT SUN SEP 25 2016

The overall organization of the depression has not changed much since this morning. The center is exposed to the north of the main area of thunderstorm activity, with some banding noted over the northeastern quadrant. Visible imagery shows that there are several smaller swirls rotating around the mean center. Dvorak intensity estimates are T2.5/35 kt from TAFB and T1.5/25 kt from SAB, so the initial intensity remains 30 kt for this advisory.

The depression is forecast to remain over warm water and to be in a low-shear environment during the next 12 to 24 hours, but the large and sprawling nature of the system suggests that any intensification should be slow to occur. By late Monday, the cyclone will be moving into an area of increasing southwesterly shear, and by Tuesday the system will be moving over cooler waters and into a more stable air mass. These conditions should result in weakening within 48 hours, and the system is expected to become a remnant low in about 3 days. The NHC intensity forecast is unchanged from the previous advisory and is once again in best agreement with the IVCN consensus model.

The depression is moving northward or 360/6 kt. The track forecast reasoning is unchanged from the previous advisory. The cyclone should move north-northeastward around the western portion of a weak ridge that extends southwestward from southern Mexico. Although most of the track models agree with this scenario, the GFS and GFDL take a stronger and deeper cyclone more northeastward, and northward around the aforementioned upper-level low later in the period. The NHC track favors the ECMWF and GFS ensemble mean solutions, which show a weaker and more shallow system turning northwestward well west of the Baja California peninsula. The new NHC forecast is essentially an update of the previous advisory.

FORECAST POSITIONS AND MAX WINDS

INIT 25/2100Z 16.1N 119.6W 30 KT 35 MPH 12H 26/0600Z 16.8N 119.4W 35 KT 40 MPH 24H 26/1800Z 17.4N 119.1W 40 KT 45 MPH 36H 27/0600Z 18.2N 118.6W 35 KT 40 MPH 48H 27/1800Z 19.1N 118.0W 30 KT 35 MPH 72H 28/1800Z 21.5N 117.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 29/1800Z 24.0N 118.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 30/1800Z 25.0N 120.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$ Forecaster Brown

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