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Tropical Storm ROSLYN Forecast Discussion


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000
WTPZ43 KNHC 280232
TCDEP3

TROPICAL STORM ROSLYN DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182016
800 PM PDT TUE SEP 27 2016

Roslyn is weakening this evening.  Strong southwesterly shear of
nearly 30 kt is affecting the tropical storm, and this has caused
the associated deep convection to be well removed to the
north-northeast of the center.  The initial intensity is
lowered a little to 35 kt, based on the latest Dvorak
classifications from TAFB, SAB, and automated values from CIMSS at
the University of Wisconsin.  The shear is expected to persist, or
even increase a little, during the next few days.  These hostile
winds combined with a stable atmosphere and decreasing sea surface
temperatures should cause additional weakening.  Roslyn will likely
weaken to a depression overnight or on Wednesday and become a
remnant low shortly thereafter when it moves over sea surface
temperatures below 26 deg C.  The NHC intensity forecast is the same
as the previous one, and generally follows the global model
guidance.

The initial motion estimate is 040/8 kt.  Roslyn should turn
northward soon as it rotates around a large cut off mid- to
upper-level low near the northern Baja California peninsula.  Once
the cyclone becomes a remnant low, it should turn northwestward in
the low-level flow before it dissipates in 2 to 3 days.  The
new NHC track forecast is a little to the east of the previous one,
and lies closest to a consensus of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 19.5N 115.9W   35 KT  40 MPH
 12H  28/1200Z 20.7N 115.9W   30 KT  35 MPH
 24H  29/0000Z 21.8N 116.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  29/1200Z 22.8N 116.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  30/0000Z 23.6N 117.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  01/0000Z...DISSIPATED

$$
Forecaster Cangialosi