Eastern Pacific Basin Tropical Cyclones

Tropical Storm Pamela Forecast Discussion

WTPZ41 KNHC 130237

Tropical Storm Pamela Discussion Number  12
NWS National Hurricane Center Miami FL       EP162021
900 PM MDT Tue Oct 12 2021

Westerly shear has continued to prevent Pamela from restrengthening 
this evening.  Although there was a significant burst of deep 
convection since the previous advisory, the center remains on the 
northwestern edge of the convective cloud mass and more recently the 
cloud tops associated with that burst has begun to warm. A blend of 
subjective Dvorak T- and CI-numbers from SAB and TAFB, and the 
latest UW-CIMSS SATCON estimate stills support an initial intensity 
of 60 kt.  Another Air Force Reserve reconnaissance aircraft is 
scheduled to investigate Pamela overnight, which should provide a 
better assessment of the cyclone's intensity.

Recent center fixes show that Pamela has made its much anticipated 
north-northeastward turn, and it is now moving 020/10 kt. The 
tropical storm should accelerate northeastward during the next 12 to 
24 hours as it gets caught in deep-layer southwesterly flow between 
a mid-level ridge over the western Gulf of Mexico, and an 
approaching mid-latitude trough to the northwest.  This motion 
should bring the center of Pamela to the coast of west-central 
mainland Mexico around 1200 UTC Wednesday morning. After that time, 
Pamela or its remnants should continue moving quickly northeastward 
across central and northern Mexico through Wednesday night.  
Although a 36-h post-tropical cyclone point is shown over southern 
Texas, the low-level center is likely to dissipate over the 
mountainous terrain of Mexico late Wednesday or Wednesday night.

Pamela will be moving over very warm SSTs of around 31C overnight, 
and that combined with a slightly more conducive upper-level wind 
pattern should allow Pamela to restrengthen into a hurricane before 
it reaches the coast of Mexico Wednesday morning.  After landfall, 
rapid weakening will occur as Pamela moves over the rugged terrain 
of west-central Mexico.  The latest NHC intensity forecast is again 
near the higher side of the guidance envelope, but it shows a 
slightly lower peak intensity before landfall than the previous 
official forecast.

Although Pamela is likely to dissipate over the rugged terrain of
Mexico, deep moisture associated with the system's remnants are
likely to spread over north-central and northeastern Mexico on
Wednesday, and then move into portions of the south-central United
States late Wednesday or Thursday.

Key Messages:

1. Pamela is forecast to restrengthen into a hurricane before it
reaches the west-central coast of Mexico on Wednesday morning, and
life-threatening storm surge and dangerous hurricane-force winds
are expected within the Hurricane Warning area.  Residents in this
area should follow any advice given by local officials.

2. Heavy rains associated with Pamela are expected to move into the
Mexican States of Sinaloa and western Durango along with southern
portions of Baja California Sur tonight and Wednesday. This will
pose a threat of significant and life-threatening flash flooding and

3. Heavy rains associated with the remnants of Pamela are expected
across portions of central Texas and southeastern Oklahoma late
Wednesday and Thursday. This may result in considerable flash and
urban flooding impacts.


INIT  13/0300Z 21.9N 108.7W   60 KT  70 MPH
 12H  13/1200Z 23.8N 106.9W   70 KT  80 MPH...NEAR THE COAST
 24H  14/0000Z 26.6N 103.3W   30 KT  35 MPH...INLAND
 36H  14/1200Z 29.7N  99.7W   20 KT  25 MPH...POST-TROP/INLAND
 48H  15/0000Z...DISSIPATED

Forecaster Brown

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