000
AXPZ20 KNHC 282123
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Thu Sep 28 2023

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 1800 UTC surface analysis and satellite imagery through
2100 UTC.

...TROPICAL WAVES...

A tropical wave is along 92W north of 07N to across portions of 
Central America, moving west at around 10 kt. Scattered moderate 
convection is noted from 05N to 12N between 86W and 94W.

A tropical wave is analyzed along 135W from 03N to 17N, moving W
at 10 to 15 kt. Scattered moderate convection is noted from 04N 
to 17N between 130W and 138W.

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

The monsoon trough extends from 09N85W to 10N109W. The ITCZ 
extends from 10N109W to 10N130W. Scattered moderate convection 
is noted from 04N to 02N and E of 110W nd from 03N to 14N and W
of 119W.

...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Surface ridging extends across the region north of 10N, 
supporting moderate NW winds persist off Baja California, which 
is accompanied by 8 to 11 ft seas in NW swell. Light to gentle 
breezes are observed elsewhere with 4 to 5 ft seas over open 
waters in southerly swell. Gentle southerly breezes and slight 
seas are evident in the Gulf of California. 

For the forecast, the long period NW swell in excess of 8 ft 
will persist off Baja California as far south as the 
Revillagigedo Islands into Fri, and will linger off Baja 
California Norte into Sat. Farther south, moderate to fresh N gap
winds will pulse to strong across the Gulf of Tehuantepec during
the early mornings though the weekend. Looking ahead, fresh to 
strong westerly gap winds over the northern Gulf of California 
will start Fri evening, ahead of a weakening cold front, possibly
reaching strong to near-gale force by Sat evening. Expect 
moderate to fresh winds off Baja California Sur early next week 
as high pressure builds in behind the front. 

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

Scattered showers and thunderstorms are noted within 90 nm of 
the coast of Nicaragua and beyond 180 nm off Costa Rica and 
western Panama, south of the monsoon trough following the passage
of a tropical wave now extending through the Yucatan peninsula. 
Light and variable breezes are evident off northern Central 
America, north of the monsoon trough, along with combined seas of
3-5 ft in southerly swell. Gentle to moderate southerly winds 
are noted south of the monsoon trough. Combined seas are 4-7 ft 
there, except 6-9 ft offshore Ecuador, highest south of the 
Galapagos Islands.

For the forecast, gentle to moderate winds will prevail to the north
of 05N with seas 5 ft or less through the weekend, with moderate
SW winds farther south. Seas may build slightly in southerly 
swell early next week. Seas south of 05N will be 6-9 ft in 
southerly swell through Fri evening, with seas highest to the SW 
of the Galapagos. 

...REMAINDER OF THE AREA...

Latest scatterometer satellite data confirm NE trade winds are 
starting to increase from 10N to 20N west of 130W, where fresh 
to strong winds are evident. This is due to high pressure 
building north of 22N, and the passage of a tropical wave over 
the tropical waters west of 130W. Long-period NW swell has been 
propagating across most of the area north of 10N and west of 
120W. The mix of the NW swell with the increasing trade winds 
has resulted in combined seas of 8 to 13 ft from 10N to 20N and 
west of 130W. Farther south, cross-equatorial southerly swell of 
8 to 10 ft is evident south of 07N and west of 105W, with 
moderate to fresh SE winds. Gentle breezes and 5 to 7 ft seas are
noted elsewhere. 

For the forecast, the tropical wave will continue westward, 
approaching 140W Fri morning. Some development of this system is 
possible over the next couple of days while it moves generally 
westward at about 10 to 15 kt. Further development of this 
system is unlikely since it will be moving into an area of 
unfavorable environmental conditions on Friday before it reaches 
the central Pacific basin. At a minimum, fresh to strong seas 
and seas of 8-12 ft will accompany this feature. High pressure 
will dominate the waters elsewhere N of the monsoon trough/ITCZ. 
The pressure gradient will weaken by the end of the week into the
weekend as the tropical wave departs and the high weakens 
leading to improving conditions. Meanwhile, for seas, the 
northerly swell of 8 ft or greater will reach to the Equator and 
west of 112W by the end of the week, while the southerly swell 
of 8 ft or greater lingers near the Equator and southward. Both 
large areas of swell should gradually decay by Sun.

$$
ERA