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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 221603
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Wed Sep 22 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
1500 UTC.

...SPECIAL FEATURES...

A Gale Warning is in effect for the Gulf of Tehuantepec tonight 
into Thu. High pressure building across the eastern slopes of the
Sierra Madre Mountains, in the wake of an early cold front, 
currently moving across the NW Gulf of Mexico, will support the 
first gap wind event in the Tehuantepec region this season. Winds
are forecast to reach minimal gale force tonight into Thu. Seas 
are expected to build to 9-11 ft with this event. Please, refer 
to the latest NWS High Seas Forecast issued by the National 
Hurricane Center at website 
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details.

A broad and elongated area of low pressure located several hundred 
miles southwest of the southern tip of the Baja California peninsula 
continues to produce disorganized showers and thunderstorms. A
1011 mb low pressure is analyzed on the 1200 UTC surface map near
15N121W. Scattered moderate to isolates strong convection is
noted within about 120 nm NW quadrant of center. Environmental 
conditions are somewhat conducive for development, and a short- 
lived tropical depression could form on Thursday or Friday while 
the low moves generally northwestward at 10 to 15 mph. This 
system is forecast to move over cooler waters and into an 
environment of stable air and strong upper- level winds this 
weekend, which should inhibit further development. The latest 
Tropical Weather Outlook gives this system a medium chance of 
tropical cyclone formation through 48 hours. Please, refer to the
latest Tropical Weather Outlook, at www.hurricanes.gov for more 
details.

...TROPICAL WAVES...

The axis of a tropical wave is along 110W and from 06N to 18N, 
moving west at 10 to 15 kt. Convection is limited near the wave
axis. 

The axis of a tropical wave is along 121W from 06N to 20N, moving
west at 10 to 15 kt. Please, refer to the Special Features section
for more details.

The axis of a tropical wave is along 140W from 05N to 18N, moving
west at 10 to 15 kt. A 1010 low pressure is along the wave axis 
near 09N140W. Scattered moderate to isolated strong convection 
is seen from 08N to 11N W of 137W. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

The monsoon trough extends from 09N85W to 10N100W to 1011 mb low
pressure located near 15N121W. The ITCZ begins near 12N122W and 
continues to beyond 09N140W. Scattered moderate to isolated
strong convection can be found N of 03N E of 84W to the coast of
Colombia, including the Gulf of Panama, from 10N to 13N between 
100W and 104W, within 120 nm NW quadrant of low pressure located
near 15N121W, and from 08N to 11N W of 137W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A ridge will continue to dominate the offshore forecast waters of
Baja California producing gentle to moderate NW to N winds. Seas
are 4 to 6 ft N of Cabo San Lazaro, and 3 to 5 ft elsewhere. In
the Gulf of Tehuantepec N to NE winds of 20-30 kt and seas to 8 
ft are now occurring. Gentle to moderate northerly winds prevail
in the Gulf of California.

For the forecast, please, see the Special Features section for 
more details on the first Tehuantepec wind event of the season.
Surface ridging will continue to dominate the offshore forecast 
waters of Baja California supporting mainly gentle to moderate NW
winds through Sun. Light to gentle winds will prevail over the 
SW Mexico offshore waters. In the northern Gulf of California, a 
surface trough will support fresh to locally strong southerly 
winds Thu night through Fri night. 

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and 
WITHIN 750 NM OF ECUADOR...

Gentle to moderate southerly winds will prevail across the offshore
waters of Costa Rica, Panama, Colombia and Ecuador during the 
forecast period, with seas of 4-6 ft in SW swell. Mainly light 
and variable winds are forecast across the offshore waters from 
Guatemala to northern Costa Rica, with seas of 3-5 ft also in SW
swell.

REMAINDER OF THE AREA...

The northern forecast waters remain under the influence of a 
surface ridge. The pressure gradient between the ridge and lower 
pressures near the monsoon trough/ITCZ supports moderate to 
locally fresh N to NE winds N of 10N and W of 120W, with seas of 
5-7 ft, except for 8 ft W of 137W. Winds across this area will 
diminish over the weekend.

$$
GR