Eastern Pacific Basin Tropical Cyclones

Hurricane Roslyn Forecast Discussion


000
WTPZ44 KNHC 220245
TCDEP4

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



Source link