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WTPZ43 KNHC 270234
TCDEP3

TROPICAL STORM ROSLYN DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182016
800 PM PDT MON SEP 26 2016

Southwesterly shear of about 20 kt is currently affecting Roslyn, and this has caused the associated convection to be confined to the north and northeast portions of the large circulation. The initial wind speed is held at 45 kt, based on the earlier ASCAT data, but the satellite presentation suggests that this could be a little generous. Weakening is expected to begin soon due to a further increase in shear and continued dry air entrainment. Roslyn will likely become a remnant low in 36 to 48 hours when it moves over sea surface temperatures lower than 26 deg C. The NHC intensity forecast is identical to the previous one, and generally follows the global model guidance.

Visible satellite images and microwave data suggest that Roslyn is moving east-northeastward at 4 kt. During the next day or so, the tropical storm is expected to move northeastward in the flow between a large mid- to upper-level cut off low near the northern Baja California peninsula and a ridge over central Mexico. After that time, a turn to the north and northwest is expected when the shallow cyclone becomes influenced by the low-level flow. The NHC track forecast is adjusted a little to the east of the previous one, trending toward the latest consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 17.2N 118.4W 45 KT 50 MPH 12H 27/1200Z 17.9N 117.7W 40 KT 45 MPH 24H 28/0000Z 19.1N 117.0W 35 KT 40 MPH 36H 28/1200Z 20.5N 116.9W 30 KT 35 MPH 48H 29/0000Z 21.7N 117.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 30/0000Z 23.5N 118.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 01/0000Z...DISSIPATED

$$ Forecaster Cangialosi

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