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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 290838

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Fri Sep 29 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 0600 UTC surface analysis and satellite imagery through
0700 UTC.


A tropical wave is along 94W north of 07N to across the Gulf of 
Tehuantepec, moving west at around 15 kt. Scattered moderate 
isolated strong convection is noted from 06N to 14N between 86W 
and 100W.

A tropical wave is analyzed along 139W from 02N to 17N, moving W
at around 15 kt. Scattered moderate isolated strong convection 
is noted from 04N to 17N between 132W and 140W.


The monsoon trough extends from 10N75W to 10N110W. The ITCZ 
extends from 10N110W to 10N137W. Scattered moderate isolated 
strong convection is noted from 05N to 11N between 105W and 123W,
and from 07N to 14N between 122W and 128W.


Surface ridging extends across the offshore waters of Mexico with
a surface trough along the Baja California Peninsula. Fresh to
strong N winds are noted in the immediate Gulf of Tehuantepec.
Winds are moderate or weaker elsewhere. Seas are 7-10 ft in NW
swell offshore Baja California, and 4-6 ft elsewhere in the open
waters. In the Gulf of California, seas are 1-3 ft except 3-4 ft
near the entrance. A tropical wave is moving across the Gulf of 
Tehuantepec as described above. 

For the forecast, the NW swell offshore Baja California will
decay early this weekend. Otherwise, mainly moderate seas will
prevail. Fresh to strong N winds will pulse in the Gulf of 
Tehuantepec, mainly at night, through the weekend. Fresh to 
strong SW winds will develop in the northern Gulf of California 
this evening through Sun night due to a passing pre-frontal
trough and weakening cold front. Winds may reach near gale force
Sat night. Winds will be moderate or weaker elsewhere.


Mainly gentle winds are N of the monsoon trough with moderate
S-SW winds S of the monsoon trough. Seas are 3-5 ft N of 07N as
well as offshore Colombia to the Azuero Peninsula, and 4-7 ft in
SE-S swell S of 07N, except 6-9 ft offshore Ecuador to the 
Galapagos Islands, highest S of the Galapagos Islands. Scattered 
showers and isolated thunderstorms are offshore Nicaragua 
northward mainly due to a departing tropical wave as described 

For the forecast, winds will be moderate or weaker across the
offshore waters through the next several days. The southerly
swell will gradually decay into the weekend. Otherwise, expect
mainly moderate seas.


A tropical wave along 139W as also described above combined with
high pressure elsewhere N of the monsoon trough/ITCZ is 
supporting fresh to strong winds from roughly 11N to 20N and W of
133W with locally higher winds as shown by a recent ASCAT 
scatterometer pass. Moderate to fresh trades prevail elsewhere N 
of 11N and W of 125W. Winds are moderate or weaker elsewhere. A 
large area of 7-11 ft seas dominates the waters W of 110W in 
mixed SE and NW swell, except up to 10-13 ft in the fresh to 
strong wind area with additional support from NE to E wind waves.
Seas are 7-10 ft in more pure SE-S swell S of 02N. Seas are 4-6 
ft across the remainder of the open waters.

For the forecast, the tropical wave will move W of 140W early
today. Associated fresh to strong winds will diminish by early
Sat. Winds of moderate or weaker will prevail elsewhere through 
the next several days. The elevated seas W of 110W will 
gradually decay through the weekend. A decaying cold front will
push S of 30N this weekend with seas building to around 8 ft 
just S of 30N Sun night into early next week. The southerly 
swell will decay slightly by the end of the weekend, however 7-9 
ft seas will linger S of the Equator through early next week.