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Hurricane Roslyn Discussion Number  13
NWS National Hurricane Center Miami FL       EP192022
900 PM MDT Sat Oct 22 2022
 
Roslyn remains a formidable hurricane with a symmetrical Central
Dense Overcast containing very intense, deep convection.  An eye has
been occasionally evident on the enhanced IR imagery.  Convective
banding features are most prevalent over the eastern and
southeastern portions of the circulation.  Upper-level outflow is
well-defined over the northern semicircle of the system.  The
current intensity is held at 115 kt in accordance with subjective
Dvorak CI numbers from SAB and TAFB.
 
The hurricane has made its expected turn to the north and the
initial motion is now near 360/10 kt.  The expected steering regime
through Sunday remains about the same as before.  Roslyn should move
around the western periphery of a mid-tropospheric high, and to the
east of a broad trough near the Baja California peninsula. The track
guidance is in good agreement on a north-northeastward motion with
further acceleration, bringing the system ashore over the Mexican
state of Nayarit on Sunday.  The official track forecast is just
slightly to the left of, but not significantly different than, the
previous NHC prediction.  This is also very close to the latest
dynamical model consensus and in between the GFS and ECMWF tracks
which have come into better agreement.
 
Prior to landfall, some increase in southwesterly shear over Roslyn
is predicted by the global models.  Therefore, slight weakening is
possible during the next 12 hours.  Nonetheless, given the conducive
thermodynamic environment including very warm ocean waters with SSTs
of 29 deg C or higher, it is expected that Roslyn will still be near
major hurricane intensity when its center crosses the coastline.
After landfall, rapid weakening will occur over the mountainous
terrain of western Mexico.
 
 
Key Messages:
 
1. Roslyn is forecast to be at or near major hurricane strength
when it passes near and makes landfall along the west-central coast
of Mexico tonight and Sunday, accompanied by damaging winds and a
dangerous storm surge.  Preparations within the Hurricane Warning
area along the west-central coast of Mexico should be rushed to
completion.
 
2. Heavy rainfall could lead to flash flooding and possible
landslides in areas of rugged terrain over coastal southwestern and
west-central Mexico.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/0300Z 20.0N 106.6W  115 KT 130 MPH
 12H  23/1200Z 21.9N 105.7W  100 KT 115 MPH
 24H  24/0000Z 24.9N 103.5W   30 KT  35 MPH...INLAND
 36H  24/1200Z 27.5N 101.5W   15 KT  15 MPH...POST-TROP/REMNT LOW
 48H  25/0000Z...DISSIPATED
 
$$
Forecaster Pasch
 
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