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WTPZ43 KNHC 272032
TCDEP3

TROPICAL STORM ROSLYN DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182016
200 PM PDT TUE SEP 27 2016

Roslyn remains a heavily sheared tropical cyclone. Satellite imagery shows that the cyclone's cloud pattern consists of a plume-shaped burst of deep convection, with the low-level center removed to the southwest of the convection due to 25 kt of southwesterly shear. Dvorak satellite classifications are unchanged since earlier, T2.5 from SAB and T3.0 from TAFB. Thus the initial intensity remains 40 kt.

The vertical shear associated with a mid- to upper-tropospheric cyclone over the northern Baja California peninsula is expected to increase further over Roslyn during the next 24 hours. In addition, SSTs should gradually be decreasing along the cyclone's path while Roslyn encounters a much drier and more stable air mass. These factors suggest that weakening should commence soon, and it could occur rather quickly. Remnant low status is now shown in 24 hours, with dissipation by day 3. The new NHC intensity forecast is a little lower than the previous one, and just below the multi-model consensus.

The initial motion estimate is 050/08. Roslyn should turn northward during the next 12 to 24 hours as it rotates around the large circulation of the cutoff low retrograding into the northeastern Pacific southwest of California. Once the system is sheared off in about 24 hours, the much shallower remnant low should turn northwestward before dissipation. The new track forecast has been shifted some to the right and is close to a blend of the ECMWF and GFS model solutions.

FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 18.8N 116.6W 40 KT 45 MPH 12H 28/0600Z 19.8N 116.3W 30 KT 35 MPH 24H 28/1800Z 21.0N 116.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 29/0600Z 22.0N 117.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 29/1800Z 22.8N 118.2W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 30/1800Z...DISSIPATED

$$ Forecaster Kimberlain

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