Eastern Pacific Basin Tropical Cyclones

Tropical Storm Orlene Forecast Discussion


000
WTPZ41 KNHC 302032
TCDEP1

Tropical Storm Orlene Discussion Number   8
NWS National Hurricane Center Miami FL       EP162022
300 PM MDT Fri Sep 30 2022

Orlene has become a little better organized since the last advisory, 
with the central convection becoming a little more concentrated.  
Satellite intensity estimates are now in the 45-65 kt range, and 
based on these the initial intensity is nudged upward to 55 kt.  
Although the organization has increased, the cyclone still looks a 
bit ragged, perhaps because the current easterly shear is a little 
stronger than the analyzed 5-10 kt.

As noted in the last advisory, Orlene is forecast to be in a moist, 
low-shear environment and over warm sea surface temperatures for the 
next 24-36 h.  These conducive conditions, combined with the small 
storm size, should allow steady to rapid strengthening as the core 
convection becomes more symmetric and concentrated.  Indeed, the 
rapid intensification indices of the SHIPS model show around a 50 
percent chance of 25-30 kt of strengthening during the next 24.  
Based this and other guidance, the new intensity forecast calls for 
Orlene to reach a peak intensity of 85 kt in 36 h.  After that, the 
global models remain in excellent agreement that the cyclone should 
encounter strong southwesterly shear that should result in quick 
weakening.  The official forecast during the weakening phase, 
including the 60-kt landfall intensity, is at the upper edge of the 
intensity guidance. However, there is still a chance that Orlene 
could be a hurricane at landfall if the shear is lighter than 
expected or the storm moves faster than currently forecast.

The initial motion is now north-northwestward or 335/4 kt.  Orlene 
is on the southwest side of a mid- to upper-level ridge over central 
Mexico, and water vapor imagery shows a developing mid- to 
upper-level trough over northwestern Mexico and the northern Baja 
California peninsula. Orlene should turn northward and north- 
northeastward between these features during the next day or so, with 
this general motion continuing for the rest of the forecast period.  
The new forecast track, which again is similar to the previous 
forecast, calls for the system to pass west of Cabo Corrientes and 
near the Islas Marias in about 48 h and then make landfall on the 
mainland coast of Mexico near 96 h.  This forecast is close to the 
consensus models, but is still slower than the GFS model. As seen 
earlier, some of the ensemble guidance still forecasts the 
possibility that Orlene will get so strongly sheared that the 
northward motion will slow over the southern Gulf of California and 
keep the center offshore through 120 h.

The forecast track and wind radii require a Hurricane Watch for Las 
Islas Marias and a Tropical Storm Watch for a potion of mainland 
Mexico at this time.  Additional watches and warnings will likely 
be required tonight or on Saturday.

Key Messages:

1. Hurricane conditions are possible in the Islas Marias on Sunday, 
where a hurricane watch has been issued.  Tropical storm conditions 
are possible over portions of southwestern and west-central Mexico 
in the tropical storm watch area.

2. Heavy rainfall from Orlene is expected to lead to flash flooding, 
as well as possible landslides in areas of mountainous terrain of 
Southwest Mexico into Monday afternoon.


FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 16.6N 107.1W   55 KT  65 MPH
 12H  01/0600Z 17.2N 107.3W   65 KT  75 MPH
 24H  01/1800Z 18.0N 107.2W   75 KT  85 MPH
 36H  02/0600Z 19.1N 107.0W   85 KT 100 MPH
 48H  02/1800Z 20.6N 106.8W   80 KT  90 MPH
 60H  03/0600Z 21.9N 106.5W   70 KT  80 MPH
 72H  03/1800Z 23.0N 106.4W   60 KT  70 MPH
 96H  04/1800Z 25.5N 106.0W   25 KT  30 MPH...INLAND
120H  05/1800Z...DISSIPATED

$$
Forecaster Beven



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