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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 261605

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Sun Sep 26 2021

Tropical Weather Discussion for the eastern Pacific Ocean from
03.4S to 30N, east of 120W including the Gulf of California, and
from the Equator to 30N, between 120W and 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
1530 UTC.


A tropical wave is along 97W, from 02N to 15N, moving west at
around 10 kt. Precipitable water animations and wave diagnostics
show a clear wave signal propagating westward off of Central 
America the past couple of days. Associated convection is 
described below.


The monsoon trough extends from northern Colombia near 11.5N72W 
to low pres 1010 mb near 11N83W to 10N87W to 10.5N113W to low
pres 1012 mb near 12N121W to low pres 1014 mb near 12N133.5W. 
The ITCZ extends from 08.5N135W to 07.5N140W. Scattered moderate 
to strong convection is noted N of 04.5N E of 81.5W. Scattered to
locally numerous moderate to strong convection is noted from
07.5N to 14.5N between 93W and 109W, N of 16N to Mexican coast
between 101W and 106W, and from 07.5N to 16.5N between 111W and


Fresh to strong N-NE winds prevail across the Gulf of Tehuantepec
this morning, extending downwind to near 14N96.5W. Associated 
seas across the area are 6 to 8 ft. Moderate NW-N winds are noted
west of Baja California and in the central Gulf of California. 
Light to gentle winds are noted elsewhere. Seas are 4 to 7 ft 
across the remainder of the open waters, and 2 to 4 ft in the 
Gulf of California, except 3 ft or less in the northern Gulf.

Fresh to strong northerly gap winds will continue across the 
Gulf of Tehuantepec through Mon morning. Mainly moderate NW-N 
winds will prevail west of Baja California, pulsing to fresh 
during the afternoon through evening hours. S-SW winds will pulse
to moderate to fresh in the northern Gulf of California. 
Otherwise, gentle to moderate winds will prevail. Large NW swell 
will impact the waters west of Baja California by late Tue. 


Fresh offshore winds prevail across the Papagayo region, with 
light to gentle winds elsewhere north of the monsoon trough. 
Gentle to moderate S-SW winds are south of the monsoon trough. 
Seas are in the 4 to 7 ft range from offshore of Colombia 
northward, and 6 to 8 ft in SW swell offshore of Ecuador.

Moderate to fresh offshore winds will pulse across the Papagayo 
region, occasionally to strong. Otherwise, light to gentle winds 
will prevail north of the monsoon trough, with mainly moderate 
winds south of the monsoon trough. Cross equatorial SW swell will
continue to propagate through the regional waters through early 
Tue, and expected to peak early this evening.


A surface trough extends from 24N130W to 17N131W. Associated 
convection has dissipated. Moderate to locally fresh NE-E winds 
are northwest of the trough. Broad and weak ridging and gentle to
moderate trades dominate the remainder of the open waters north 
of the convergence zone. Gentle to moderate southerly winds 
prevail south of the convergence zone. Seas are in the 5 to 8 ft
range north of 11N, and 6 to 7 ft south of 11N, except to 8 ft 
between 93W and 125W.

Winds associated with the trough along 130W will diminish 
through late Sun as it shifts westward and weakens. A cold front 
is expected to move into the NW waters Mon night into early Tue 
and quickly weaken as it moves southward and gradually dissipates
along 21N by the end of the week. Associated long period NW 
swell is expected to build seas to 8 to 11 ft to the west of 
120W, spreading southward through the middle of this coming week.