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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 201604

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Tue Oct 20 2020

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1550 UTC. 


A tropical wave axis extends along 88W from 06N to 18N, moving W
at 10 to 15 kt. Scattered moderate convection from 06N-13N between
85W to 91W. 

A tropical wave axis extends along 120W from 04N to 17N, moving 
W at 10 to 15 kt. Scattered moderate convection is noted mainly 
east of the wave from 11N-17N between 114W-119W.


The monsoon trough axis extends from 11N81W across Costa Rica
to a 1008 mb low pres near 10.3N100W to 11N115W, then resumes
west of the trough near 12N121W to 09N135W. The ITCZ continues
from 09N135W to beyond 07N140W. Scattered moderate to strong 
convection is noted near the coast of Costa Rica and from 10N 
to 14N between 90W and 96W.


The pressure gradient between a high pressure ridge to the west 
of Baja California and a 1007 mb low pressure over southern 
California is supporting moderate to fresh NW winds across the 
offshore waters of northern and central Baja California. Farther 
south, including the Gulf of California, except for a small area 
of strong winds across the Gulf of Tehuantepec, gentle to 
moderate breezes persist. Seas are generally in the 4 to 7 ft 
range in mixed N and SW swell, and 3 ft or less across all but 
the mouth of the Gulf of California.

Winds will remain fresh through Tue night offshore the Baja
California peninsula as low pressure deepens over the SW U.S. 
Locally strong winds are expected within 120 nm of Baja 
California Norte and near Punta Eugenia through Tue evening, 
with seas of 6-7 ft. Mostly gentle to moderate breezes and seas
5 ft or less will persist elsewhere. 

Gulf of Tehuantepec: Winds across the Gulf of Tehuantepec are 
expected to remain northerly near 20 kt for the next few days 
with nocturnal pulses of 25-30 kt each late night and early 
morning through Wed, and extend only 90-120 nm downwind in a 
relatively narrow plume. Seas will peak each early morning at
7-9 ft. 

Looking ahead, the first strong cold front of the season will
move across northern Mexico and much of the Gulf of California
Sun night through Mon. This will bring strong northerly winds
spreading across the northern half of the Gulf on Mon, with gale
force wind gusts.


Moderate to fresh SW winds prevail south of the monsoon trough,
along about 09N-10N, and east of 97W. Seas south of Costa Rica 
and Panama are 7 to 9 feet in mixed SW swell. These conditions
will continue with little change through Wed before winds 
subside slightly and long period SW swell begins to slowly fade 
across the region. 

Broad low pressure across the western Caribbean is aiding in
producing the area of fresh winds south of Panama and Costa 
Rica, and is also helping to produce very active weather across 
these eastern waters east of 94W. This active weather is 
expected to continue through Tue night before beginning to 
diminish as the low pressure across the western Caribbean lifts 
NW towards the Gulf of Mexico.


A 1030 mb high pressure near 32N140W extends a ridge SE to near 
19N122W, and is supporting moderate to fresh trade winds from 
roughly 12N to 25N mainly west of 120W. Seas are generally 6-7 
ft across this zone. Expect little change in this pattern through

Scattered showers are noted from 25N to 28N between 132W and 
137W, to the southeast of a deep layered upper trough extending 
across the NW corner of the discussion area. This trough will 
drift NW during the next few days, with weather improving in its 

Farther east, seas will remain 7-8 ft near the monsoon trough 
between 108W and 120W, due in part to moderate SW winds south of
the monsoon trough and longer period SW swell moving through the
area. Look for both winds and seas to diminish slightly across 
this area by late Tue afternoon. Winds will freshen Thu through
Sat to the west of 130W, with seas building 7-8 ft.