000
AXPZ20 KNHC 300805
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Sep 30 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
0710 UTC.

...TROPICAL WAVES...

A tropical wave is along 99W north of 06N, moving west at 5 to 10
kt. Scattered moderate isolated strong convection is noted from
10N to 13N between 96W and 101W.

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

The monsoon trough extends from 09N75W to 11N88W to 10N115W to
11.5N121W to 07.5N128W. The ITCZ extends from 07.5N128W to
09N140W. Scattered moderate isolated strong convection is noted
from 04N to 08N between 81W and 88W, from 09N to 13N between 86W
and 96W, from 06N to 10N between 109W and 113W, and from 05N to 
17N between 124W and 140W.

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

Surface ridging extends across the offshore waters of Mexico with
a surface trough from SW Arizona to across the northern Gulf of
California and Baja California Norte. Fresh to strong S-SW winds
are in the northern Gulf of California due a tightening pressure
gradient, per a recent ASCAT scatterometer pass. Fresh to 
strong N winds are noted in the immediate Gulf of Tehuantepec. 
Winds are moderate or weaker elsewhere. Seas are 6-8 ft in 
decaying NW swell offshore Baja California, and 4-6 ft elsewhere 
in the open waters. In the Gulf of California, seas are 3-5 ft in
the northern Gulf, and 1-3 ft elsewhere, except 3-4 ft near the 
entrance. A tropical wave is moving across portions of southern 
Mexico as described above. 

For the forecast, the NW swell offshore Baja California will
continue to decay today. Otherwise, mainly moderate seas will 
prevail through the middle of next week. Fresh to strong N winds
will pulse in the Gulf of Tehuantepec, mainly at night, through 
the weekend. Fresh to strong SW winds will pulse in the northern 
Gulf of California through Sun night due to a passing pre-frontal
trough and weakening cold front, near gale-force tonight. Winds 
will be moderate or weaker elsewhere. Looking ahead, an area of 
low pressure is expected to form well south of the coast of 
southwestern Mexico early next week. Environmental conditions are
expected to support gradual development of the disturbance, and 
a tropical depression could form during the middle to later part 
of the week while the system moves generally northwestward.

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

Winds are moderate or weaker across the offshore waters. Seas 
are 3-5 ft N of 10N as well as offshore Colombia to the Azuero 
Peninsula, and 4-7 ft in SE-S swell elsewhere S of 10N, except 
5-8 ft offshore Ecuador to the Galapagos Islands, highest S of 
the Galapagos Islands. Widely scattered showers and isolated 
thunderstorms are offshore western Panama northward.

For the forecast, winds will be moderate or weaker across the
offshore waters through the next several days. The southerly
swell will gradually decay this weekend, then may build back 
offshore Ecuador to the Galapagos Islands by the middle of next 
week. Otherwise, expect moderate seas to prevail across the
remainder of the waters.

...REMAINDER OF THE AREA...

High pressure N of the monsoon trough/ITCZ is supporting fresh 
to strong winds from 13N to 17N and W of 136W. Moderate to fresh
trades prevail elsewhere from 12N to 27N and W of 130W. Winds 
are moderate or weaker elsewhere as reported by recent ASCAT 
scatterometer data. A shrinking area of 8-11 ft seas dominates 
the waters from the Equator to 22N and W of 110W in mixed SE and
NW swell. Seas are 8-11 ft in more pure SE-S swell S of the 
10N and W of 95W. Seas are 4-7 ft across the remainder of the 
open waters, except 8-9 ft N of 25N between 119W and 126W in old
N swell.

For the forecast, the fresh to strong winds will diminish early
today. Winds of moderate or weaker will prevail elsewhere and
otherwise 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 by tonight with seas building to around
8 ft just S of 30N Sun afternoon into early next week, with a 
brief accompanying fresh northerly wind shift behind it. 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. 

$$
Lewitsky