Eastern Pacific Basin Tropical Cyclones

Hurricane Roslyn Forecast Discussion

WTPZ44 KNHC 220846

Hurricane Roslyn Discussion Number  10
NWS National Hurricane Center Miami FL       EP192022
300 AM MDT Sat Oct 22 2022

Roslyn has intensified rapidly during the past 24 hours.  A
well-defined eye has formed in infrared satellite imagery since the
time of the previous advisory, with cloud tops in the surrounding
central dense overcast (CDO) as cold as -80 degrees Celsius.  The
satellite presentation has improved significantly enough to yield
Dvorak data-T numbers of 5.5 (102 kt) from TAFB and SAB at 06 UTC.
Since Roslyn's structure has improved a bit since that time, the
initial intensity is set at 105 kt.

The initial motion is now northwestward, or 315/6 kt.  Roslyn is
expected to continue recurving around the western periphery of a
mid-level high centered over Mexico during the next 36 hours.  The
bulk of the track models indicate that the hurricane will pass just
offshore of Cabo Corrientes, Mexico, by tonight, and then
accelerate north-northeastward on Sunday, likely making landfall
on the coast of the Mexican state of Nayarit.  After landfall,
Roslyn's remnants are expected to accelerate toward the northeast
over northern Mexico.  The updated NHC track forecast shows a
slightly wider recurvature than the previous forecast during
the first 24 hours, following the tightly clustered model
solutions, but the expected landfall ends up in the same general
location as before.

Roslyn has roughly another 12 hours before deep-layer southwesterly
shear increases to moderate levels.  But before that happens, the
environment appears conducive for additional strengthening,
possibly still at a rapid rate.  SHIPS Rapid Intensification
indices indicate there is a 50/50 chance of a 20-kt increase in
winds over the next 12 hours, and given the short-term satellite
trends, the NHC intensity forecast now shows Roslyn reaching
category 4 intensity later today.  The increase in shear should
induce some weakening in the last few hours while Roslyn approaches
the coast of Mexico, but the storm could still be at or near major
hurricane strength around the time of landfall on Sunday.  After
landfall, the 5000- to 8000-ft mountains of the Sierra Madre
Occidentals are expected to significantly disrupt Rosalyn's
circulation, and even though a remnant low is shown in the forecast
over the Mexican Plateau at 48 hours, it's likely that Rosalyn will
have dissipated by that time.

Key Messages:

1. Roslyn is forecast to be near or at major hurricane strength
when it passes near and makes landfall along the west-central coast
of Mexico Saturday night 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.


INIT  22/0900Z 17.3N 106.1W  105 KT 120 MPH
 12H  22/1800Z 18.3N 106.4W  120 KT 140 MPH
 24H  23/0600Z 20.1N 106.2W  105 KT 120 MPH
 36H  23/1800Z 22.6N 105.0W   65 KT  75 MPH...INLAND
 48H  24/0600Z 25.7N 102.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  24/1800Z...DISSIPATED

Forecaster Berg

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