Eastern Pacific Basin Tropical Cyclones

Tropical Storm Orlene Forecast Discussion


953 
WTPZ41 KNHC 010834
TCDEP1

Tropical Storm Orlene Discussion Number  10
NWS National Hurricane Center Miami FL       EP162022
300 AM MDT Sat Oct 01 2022

Orlene has changed little in organization overnight.  Recent 
microwave satellite imagery revealed Orlene is trying to maintain 
an inner core despite some dry air attempting to wrap in from its 
east. Scatterometer data indicated that the low-level center was 
slightly to the southeast of what was previously estimated.  These 
data suggest that the cyclone may be feeling the affects of some 
southeasterly shear, possibly caused by flow around the ridge to its 
east.  The initial intensity remains unchanged at 55 kt and is based 
off a blend of the latest Dvorak intensity estimates from SAB and 
the UW-CIMSS ADT. 

The storm has about 36 h left to take advantage of the relatively 
low vertical wind shear and moist thermodynamic environment.  After 
36 h, increasing southwesterly shear should cause Orlene to steadily 
weaken before reaching the coast of mainland Mexico early next week. 
The cyclone is then expected to dissipate shortly after moving 
inland.  The overall model guidance continues to back off on the 
peak intensity of Orlene, likely due to the fact the cyclone has not 
been able to strengthen as quickly as expected over the past day or 
so.  The NHC intensity forecast is slightly lower than the previous 
one, and is on the high end of the guidance. 

Orlene is moving slowly northward, at only 4 kt, to the west of a 
mid-level ridge.  By tonight, the cyclone should turn 
north-northeastward in the flow between the ridge and an upper-level 
trough over northwestern Mexico and the northern Baja California 
peninsula. This north-northeastward motion is forecast to continue 
until Orlene dissipates over mainland Mexico.  The latest NHC track 
forecast was nudged just east of the previous one, mainly due to the 
slight southeastward adjustment of the initial position.

Based on the the forecast track, intensity, and wind radii, 
Hurricane or Tropical Storm Warnings will likely be required for 
portions of the Hurricane Watch area later today.


Key Messages:

1. Hurricane conditions are possible in the Islas Marias Sunday 
night, with tropical storm conditions beginning late Sunday.  
Tropical storm conditions are expected within the tropical storm 
warning area along the west-central coast of Mexico on Sunday.  
Tropical storm conditions are possible over other portions of 
southwestern and west-central Mexico in the tropical storm watch 
area tonight or Sunday.

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


FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 17.2N 107.0W   55 KT  65 MPH
 12H  01/1800Z 17.9N 106.9W   65 KT  75 MPH
 24H  02/0600Z 18.9N 106.8W   75 KT  85 MPH
 36H  02/1800Z 20.0N 106.5W   80 KT  90 MPH
 48H  03/0600Z 21.2N 106.2W   70 KT  80 MPH
 60H  03/1800Z 22.5N 105.9W   60 KT  70 MPH
 72H  04/0600Z 23.7N 105.6W   30 KT  35 MPH...INLAND
 96H  05/0600Z...DISSIPATED

$$
Forecaster Latto




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