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Hurricane Roslyn Discussion Number 9
NWS National Hurricane Center Miami FL EP192022
1000 PM CDT Fri Oct 21 2022
Roslyn has become even better organized on satellite images. The
system has a fairly symmetrical central dense overcast (CDO)
containing extremely deep convection with cloud tops colder than -80
deg C. There are a number of convective bands surrounding the CDO,
and the upper-level outflow pattern is well-defined. Subjective
Dvorak intensity estimates from both TAFB and SAB are now at 77 kt,
so the advisory intensity is increased to 75 kt, making the cyclone
a hurricane. Objective Dvorak estimates are somewhat lower at this
time, but these will likely catch up to the subjective intensity
values soon. Roslyn is a rather compact hurricane, with its
inner-core region covering an area about 30 n mi in diameter.
Center fixes from geostationary and microwave imagery indicate that
the motion continues to be west-northwestward, or about 295/6 kt.
The track forecast scenario is basically unchanged from the previous
advisory package. A mid-level anticyclone to the north of the
hurricane is shifting eastward as a broad trough approaches the Baja
California peninsula. This evolution of the steering pattern should
result in Roslyn turning northward and north-northeastward over the
next 36 hours. The official track forecast is about the same as the
previous one and is near the eastern side of the model guidance
suite. This is also very close to the latest corrected model
consensus, HCCA, prediction.
Roslyn is expected to remain within a low vertical shear environment
into Saturday, with some increase in shear beginning in 24 hours or
so. Further strengthening seems likely during the next 12 to 24
hours. The SHIPS Rapid Intensification index shows a 40 percent
chance for a 25-kt intensity increase in 24 hours. Therefore the
official intensity forecast, although it is above the deterministic
guidance, may be conservative and it is certainly possible that
Roslyn could become a major hurricane before landfall.
Key Messages:
1. Roslyn is forecast to be near major hurricane strength 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 in effect
for a portion of the west-central coast of Mexico.
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 22/0300Z 16.7N 105.6W 75 KT 85 MPH
12H 22/1200Z 17.6N 106.0W 90 KT 105 MPH
24H 23/0000Z 19.3N 106.2W 95 KT 110 MPH
36H 23/1200Z 21.4N 105.6W 95 KT 110 MPH
48H 24/0000Z 24.4N 104.0W 25 KT 30 MPH...INLAND
60H 24/1200Z 27.5N 101.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
72H 25/0000Z...DISSIPATED
$$
Forecaster Pasch
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