Eastern Pacific Basin Tropical Cyclones

Tropical Storm Roslyn Forecast Discussion


000
WTPZ44 KNHC 211456
TCDEP4

Tropical Storm Roslyn Discussion Number   7
NWS National Hurricane Center Miami FL       EP192022
1000 AM CDT Fri Oct 21 2022

Visible satellite imagery suggests that Roslyn is getting better 
organized, with the formation of a central dense overcast with 
overshooting tops near the center.  A recent GMI overpass indicates 
these tops are related to a partial eyewall that has formed under 
the overcast.  The various subjective and objective satellite 
intensity estimates remain near 55 kt, and based on these data the 
initial intensity is unchanged from the previous advisory.  One note 
is that there seem to be a tongue of dry air wrapping cyclonically 
around the CDO from the northwest to southeast.  It should be noted 
that the Air Force Reserve Hurricane Hunter mission scheduled for 
this afternoon has been canceled due to mechanical issues.

The recent satellite data suggest that the center is a little south 
of the previous track, and the initial motion is a somewhat 
uncertain 300/6 kt.  Despite this shift, there is little change in 
the track forecast philosophy from the previous advisory, as Roslyn 
is still expected to recurve around the western edge of a mid-level 
ridge that will migrate eastward across Mexico during the next 
couple of days.  This will lead to the center passing near or a 
little west of Cabo Corrientes in about 36 h, followed by landfall 
in mainland Mexico.  There is little change to either the forecast 
guidance or the official forecast track since the last advisory, 
and the new track lies near or just east of the various consensus 
models.

Since Roslyn is developing a better defined inner core, its current 
environment of light shear and warm sea surface temperatures could 
allow for rapid intensification. One obstacle to that, though, is 
the dry air currently near the core.  The GFS, HRWF, and HMON models 
forecast this dry air to get mixed out during the next 12-24 h, and 
based on this premise, the new intensity forecast will follow the 
previous forecast in showing rapid strengthening to a peak intensity 
of 95 kt before landfall.  After landfall, Roslyn is expected to 
rapidly weaken over the mountains of Mexico, and although the 
official forecast shows a remnant low over northern Mexico in 72 
hours for continuity, Roslyn will likely dissipate before then.

The new forecast requires a northward extension of the hurricane 
warning along the coast of Mexico.  Additional watches and warnings 
will likely be required on the next advisory.


Key Messages:

1. Roslyn is forecast to be a hurricane when it passes near and
makes landfall along the west-central coast of Mexico late Saturday
and Sunday, accompanied by strong winds and a potentially dangerous
storm surge.  A Hurricane Warning is now in effect for a portion of
the west-central coast of Mexico and will likely be extended
northward later today.

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  21/1500Z 16.4N 104.4W   55 KT  65 MPH
 12H  22/0000Z 17.0N 105.1W   70 KT  80 MPH
 24H  22/1200Z 18.1N 106.0W   85 KT 100 MPH
 36H  23/0000Z 19.6N 106.3W   95 KT 110 MPH
 48H  23/1200Z 21.7N 105.8W   95 KT 110 MPH
 60H  24/0000Z 24.4N 104.4W   45 KT  50 MPH...INLAND
 72H  24/1200Z 27.1N 102.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  25/1200Z...DISSIPATED

$$
Forecaster Beven



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