000
AXPZ20 KNHC 182004
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Mon Sep 18 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
1900 UTC.

...SPECIAL FEATURE...

A tropical wave extends its axis near 115W S of 18N, moving W at
around 10 kt. Low pressure of 1007 mb is along the tropical wave
near 14N115W. Scattered moderate isolated strong convection is 
noted within 240 nm of the low. Current associated winds are 
around 20 kt per recent ASCAT scatterometer data, with seas to 
around 7 ft. Environmental conditions are expected to remain 
conducive for further development through midweek. A tropical 
depression is likely to form during the next couple of days while
the system moves generally west- northwestward over the central 
and western portions of the basin. There is a high probability of
tropical cyclone development with this system over the next 2 
days. Please refer to the latest NHC Tropical Weather Outlook at 
www.hurricanes.gov for more details.

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

The monsoon trough extends from 10N75W to 10N103W, then resumes
from low pressure near 14N115W to 10N135W. The ITCZ extends 
from 10N135W to 09N140W. Scattered moderate isolated strong 
convection is noted from 03N to 09N between 77W and 86W, from 04N
to 14N between 86W and 100W, from 14N to 18N between 105W and 
110W, and from 07N to 11N between 120W and 127W. Scattered 
moderate convection is noted from 06N to 14N between 129W and 
140W.

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

A surface ridge dominates the offshore forecast waters of Baja 
California supporting moderate to fresh NW winds and seas of 5-7
ft. In the Gulf of California, gentle winds prevail. Seas are 
1-3 ft, except 3-4 ft near the entrance to the Gulf. Fresh to 
strong N-NE winds are likely in the Gulf of Tehuantepec, along 
with seas of 5-8 ft. Light to gentle winds, and seas of 4-6 ft 
in SE to S swell, except NW swell offshore Baja California, 
prevail elsewhere across the Mexican offshore waters.

For the forecast, the surface ridge will remain in control of the
weather pattern across the region over the next several days.
Moderate to fresh NW to N winds will prevail over the waters
west of Baja California through the early part of the week,
locally strong near and south of Punta Eugenia, with seas of 6-7
ft. Fresh to strong winds in the Gulf of Tehuantepec will 
diminish Tue, then may return Thu night into Fri. Fresh to 
locally strong SW winds may develop in the northern Gulf of 
California Wed night through Thu.

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

Moderate to fresh gap winds are noted over and downstream of the
Gulf of Papagayo along with seas of 5-6 ft, with moderate N 
winds are in the Gulf of Panama, and light to gentle winds 
elsewhere north of the monsoon trough. South of the monsoon 
trough, gentle winds prevail, reaching moderate speeds offshore 
southern Colombia and between Ecuador and the Galapagos Islands. 
Seas are 3-5 ft elsewhere, except 5-6 ft offshore Ecuador to the
Galapagos Islands.

For the forecast, gentle to moderate southerly winds over the 
waters between Ecuador and the Galapagos Islands will prevail 
through mid week before diminishing. Moderate to fresh gap winds 
will prevail in the Gulf of Papagayo through Tue before 
diminishing slightly, then fresh to strong Wed night. Elsewhere,
light to gentle winds will prevail. 

...REMAINDER OF THE AREA...

Refer to the Special Features section above for details on the 
developing broad area of low pressure along a tropical wave along
115W.

Moderate to locally fresh winds and seas of 6-8 ft are impacting
the waters from north of the monsoon trough/ITCZ to 22N and west 
of 115W. Gentle to moderate southerly winds are south of 04N 
along with seas of 5-8 ft in long period SE swell. Light to 
gentle anticyclonic winds and 4-5 ft seas are north of 25N and 
west of 120W under a weak pressure pattern. Elsewhere, winds are
moderate or weaker with seas of 4-7 ft. 

For the forecast, winds and seas may increase soon in association
with the broad area of low pressure along the tropical wave 
discussed above. Elsewhere, high pressure will prevail across the
northern waters, particularly north of 15N and west of 110W. 
Under the influence of this system, gentle to moderate 
anticyclonic flow is expected with seas in the 4-7 ft range. NW 
swell of around 8 ft will drop just south of 30N between 120W and
135W by mid-week before decaying. South of 05N, moderate 
southerly winds will prevail, with moderate southerly swell 
persisting through the weekend.

$$
Lewitsky