Eastern Pacific Basin Tropical Cyclones

Hurricane Orlene Forecast Discussion


690 
WTPZ41 KNHC 020851
TCDEP1

Hurricane Orlene Discussion Number  15
NWS National Hurricane Center Miami FL       EP162022
300 AM MDT Sun Oct 02 2022

Orlene has continued to strengthen rapidly over the past several
hours.  On GOES-17 satellite imagery, the system has a
well-defined eye with a temperature near -4 deg C surrounded by
very cold tops to near -80 deg C, particularly over the western
eyewall.  Based on objective T-numbers from UW-CIMSS, the current
intensity estimate is raised to 115 kt.  Subjective Dvorak 
estimates are somewhat lower, but these are constrained by the rules 
of the technique.  Over the 15-h period from 1800 UTC yesterday to 
the time of this advisory, the intensity of the hurricane has 
increased by an estimated 40 kt.  Orlene remains a small tropical 
cyclone, with its destructive core covering an area some 20 n mi in 
diameter.  The system continues to exhibit strong upper-level 
outflow with an outflow jet noted over the northern part of the 
circulation.

In the short term, environmental conditions are expected to be
conducive for further strengthening, with moderate vertical shear
prevailing for the next 12 hours or so.  Thereafter, although
thermodynamic factors should remain conducive, the global models
show a substantial increase in southwesterly vertical shear over
the hurricane.  This is also suggested by water vapor imagery which
depicts a broad upper-level trough north of 20N and west of the
Baja California peninsula.  Since Orlene is a small hurricane, it
should be especially susceptible to the negative effects of the
increasing shear.  Therefore a weakening trend is predicted to
begin after 12 hours.  Nonetheless, given Orlene's recent
strengthening , the official intensity forecast is above all of
the model guidance.  It is anticipated that the system will be at
or near hurricane strength when it reaches the coast of mainland
Mexico.  After landfall, the cyclone will quickly weaken over the
mountainous terrain.

Orlene continues moving northward or at about 005/6 kt.  During
the next 48 hours or so, the hurricane should be steered by the
flow between the mid/upper-level trough near Baja California and
northwestern Mexico and a subtropical ridge to its east.  A slight
bend of the heading toward the north-northeast is likely later
today.  The official forecast track is very close to the previous
NHC track, and is a little to the east of the dynamical model 
consensus.  The GFS model is significantly farther to the right and 
faster than the other track guidance.


Key Messages:

1. Hurricane conditions are expected in the Islas Marias tonight,
with tropical storm conditions beginning later today. A Hurricane
Warning is in effect for a portion of west-central mainland Mexico,
where hurricane conditions are expected on Monday with tropical
storm conditions beginning early Monday.  Preparations to protect
life and property should be rushed to completion.

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


FORECAST POSITIONS AND MAX WINDS

INIT  02/0900Z 19.0N 106.8W  115 KT 130 MPH
 12H  02/1800Z 19.7N 106.6W  125 KT 145 MPH
 24H  03/0600Z 20.9N 106.3W  105 KT 120 MPH
 36H  03/1800Z 22.0N 106.0W   85 KT 100 MPH
 48H  04/0600Z 22.8N 105.7W   65 KT  75 MPH...INLAND
 60H  04/1800Z 23.2N 105.4W   40 KT  45 MPH...INLAND
 72H  05/0600Z...DISSIPATED

$$
Forecaster Pasch




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