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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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