000
AXPZ20 KNHC 220141
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Wed Jul 21 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 0000 UTC surface analysis and satellite imagery through
0100 UTC.

...TROPICAL WAVES...

A tropical wave is along 94W/95W, from 03N northward into 
southern Mexico, moving slowly west around 5 kt. No significant 
convection is noted with this tropical wave.

Another tropical wave is near 99W, from 03N northward into 
southern Mexico, moving slowly west around 5 kt. Scattered
moderate and isolated strong convection is noted from 05N to 13N
between 95W and 102W.

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

The monsoon trough extends from northern Colombia near 10N74W to
07N96W to 11N126W to 10N140W. Scattered moderate and isolated 
strong convection is evident from 02N to 08N between 79W and 91W,
within 300 nm north of the monsoon trough between 10W and 124W,
within 150 nm south of the monsoon trough between 102W and 131W,
and from 10N to 12N between 131W and 140W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Fresh to strong northerly gap winds continue in the Gulf of 
Tehuantepec. This is related to a passing tropical wave, with 
seas estimated to be 4 to 6 ft in this area. Light to gentle 
breezes with 3 to 5 ft seas are evident elsewhere off southern 
Mexico, with a component of SW swell. A few showers and 
thunderstorms are active ahead of the tropical wave beyond 90 nm 
off the coast of Chiapas. Farther north, mainly moderate to 
locally fresh NW winds prevail across the waters off Baja 
California, between weak high pressure west of the region and 
lower pressure across northern Mexico, along with 4 to 6 ft seas 
in this area. Gentle to moderate SE to S winds and slight seas 
are noted over the Gulf of California. Scattered showers and 
thunderstorms are propagating from mainland Mexico into portions 
of the Gulf of California, mainly the northern Gulf early this 
evening.

For the forecast, the fresh to strong N winds will continue to 
pulse across the Tehuantepec region through Sat night. Moderate 
to locally fresh winds offshore of Baja California will diminish 
by early Thu. Moderate to locally fresh SE flow will develop in 
the Gulf of California Thu through Sat. Winds and seas may be 
higher in the Gulf of California in the evenings as showers and 
thunderstorms over mainland Mexico move into the Gulf. 

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

High pressure over the NW Caribbean is helping to funnel fresh to
strong NE to E winds over the Papagayo region with seas to 8 ft.
Elsewhere, moderate or weaker winds prevail. Seas are 4 to 6 ft,
primarily in long period SW swell. Scattered showers and
thunderstorms are active beyond 150 nm off Costa Rica and western
Panama, on the south side of the monsoon trough.

For the forecast, High pressure over the NW Caribbean will  
continue to support fresh to strong NE to E winds over the 
Papagayo region through at least Sat, mainly during the overnight
and early morning hours. Moderate or weaker winds are forecast 
elsewhere. A moderate southerly swell will impact the waters west
of Ecuador by Thu. Winds will freshen south of the monsoon 
trough this weekend allowing for seas to build across the waters 
north of 02N. 

REMAINDER OF THE AREA...

The remnant low pressure of what was Guillermo is near 17N133W,
with an estimated pressure of 1009 mb. There is no thunderstorm 
activity near this feature, and an earlier scatterometer 
satellite pass indicated a large area of moderate to fresh to 
locally fresh NE winds on the northwest side of the low pressure,
between the low and ridging dominating the waters north of 20N 
and west of 120W. Seas are estimating to be 8 to 10 ft related to
this. Seas of 5 to 8 ft prevail elsewhere across the open 
waters.

For the forecast, the remnant low of Guillermo will open up to a
trough with diminishing winds through the end of the week, while
associated seas will be slower to decay. Otherwise, the ridge 
will linger across the waters north of the convergence zone with 
fairly tranquil marine conditions expected as Guillermo spins 
down. A moderate SW swell will build seas to 7 to 9 ft south of
07N and east of 110W by the end of the week, then decaying this
weekend.

$$
Lewitsky