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WTPZ41 KNHC 311438
TCDEP1

TROPICAL STORM VANCE DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP212014
800 AM PDT FRI OCT 31 2014

There hasn't been a lot of significant change with the structure of Vance during the past several hours. While the central convection has weakened some, the convection associated with a banding feature on the east side has increased. Dvorak estimates are similar to 6 hours ago, so the initial wind speed will remain 40 kt. Vance continues to struggle with southwesterly shear and dry air. Most of the models, however, suggest that the shear should abate over the weekend, with increasing moisture and upper-level divergence expected as well. The latest model guidance generally shows a higher peak intensity, and the NHC forecast is now a bit higher at 48-72 hours. After that time, a significant increase in southwesterly shear is forecast, which will likely cause weakening while the cyclone approaches Mexico.

The center has not been easy to track with this cyclone, but the latest microwave and visible satellite data suggest it has been creeping toward the south-southwest. A ridge over the eastern Pacific is expected to move eastward over the next few days, steering the cyclone more steadily west-southwestward by late today, westward tomorrow, and to the northwest by late this weekend. Vance is then forecast to turn northward and then northeastward ahead of a trough moving over Baja California. While the models are in good agreement on the overall track, there remains some spread in the timing of the turn toward Mexico. The guidance is generally faster than the last cycle, so the updated NHC forecast follows that trend. Overall the forecast is also little east of the previous one, mostly because of the initial motion and position.

FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 10.1N 100.8W 40 KT 45 MPH 12H 01/0000Z 9.7N 101.7W 45 KT 50 MPH 24H 01/1200Z 9.6N 103.2W 50 KT 60 MPH 36H 02/0000Z 10.2N 105.2W 55 KT 65 MPH 48H 02/1200Z 11.4N 107.0W 65 KT 75 MPH 72H 03/1200Z 15.0N 109.3W 75 KT 85 MPH 96H 04/1200Z 19.3N 107.9W 55 KT 65 MPH 120H 05/1200Z 23.5N 105.0W 30 KT 35 MPH...INLAND

$$ Forecaster Blake



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