716 
AXPZ20 KNHC 092143
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Mon Jun 9 2025

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.

...SPECIAL FEATURES...

Hurricane Barbara, the first hurricane of the east Pacific
Hurricane Season, is centered near 18.2N 106.8W at 09/2100 UTC, 
moving northwest at 9 kt, and this motion is expected to continue
for the next couple of days. Estimated minimum central pressure 
is 991 mb. Maximum sustained wind speed is 65 kt with gusts to 80
kt. A weakening trend should begin tonight, and the system is 
forecast to become a remnant low by Wednesday. Seas in excess 
of 12 ft reach as far as 135 nm to the northeast of the center, 
with maximum seas to 25 ft. Swells generated by Barbara will 
affect portions of the coast of southwestern Mexico during the 
next few days. These swells are likely to cause life-threatening 
surf and rip current conditions. Please consult products from 
your local weather office. Gusty winds are likely along coastal 
areas of southwestern Mexico tonight. Scattered moderate to
strong convection can be found within 75 nm NW and 30 nm SE 
semicircles of center.

Tropical Storm Cosme is centered near 15.0N 113.9W at 09/2100 
UTC, moving northwest at 8 kt. A turn toward the north with a 
decease in forward speed is expected by early Tuesday, followed 
by a faster north-northeast motion late Tuesday through 
Wednesday. Estimated minimum central pressure is 992 mb. Maximum 
sustained wind speed is 60 kt with gusts to 75 kt. Some 
additional strengthening is forecast, and Cosme could become a 
hurricane tonight. Rapid weakening is expected late Tuesday and 
Wednesday. Cosme will likely become a post-tropical low in a 
couple of days. Scattered moderate to strong convection is noted 
within 60 nm of center. 
 
Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website - 
https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest 
Barbara and Cosme NHC Forecast/Advisories and Public Advisories 
at www.hurricanes.gov for more details.

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

The monsoon trough extends from a 1009 mb low pressure located
over northern Colombia near 10N75W to 10N92W to 15N102W, then 
continues S of T.S. Cosme from 12N113W to 09N122W. The ITCZ 
stretches from 09N122W to 07N135W to beyond 06N140W. Scattered 
moderate to isolated strong convection is noted from 04N to 09N E
of 87W to the coast of Colombia. Scattered moderate convection 
is seen from 07N to 13N between 89W and 95W, and from 06N to 10N 
between 120W and 124W.

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

Please read the Special Features section for information on
Hurricane Barbara and Tropical Tropical Storm Cosme forecast to
be a hurricane tonight.

High pressure of 1034 mb located well NW of the forecast area
extends a ridge SE reaching the offshore waters of Baja California.
This system is producing moderate to locally fresh NW winds, 
with seas of 4 to 6 ft. Gentle breezes and moderate seas persist 
off southern Mexico outside of the area impacted by Hurricane 
Barbara which is mainly off Colima and Jalisco currently. Gentle
to moderate southerly winds are observed over most of the Gulf 
of California, except N of 30N where winds are mainly light.
Slight seas dominate the Gulf, with seas of 3 to 4 ft near the
entrance to it. 

For the forecast, rough to very rough seas, currently affecting
the offshore waters of Colima and Jalisco will propagate northward
reaching the waters between Los Cabos and Las Maria Islands on 
Tue. Mariners should continue to monitor the latest statements 
from the National Hurricane Center, and plan their routes 
accordingly to avoid the adverse marine conditions. The remnant 
lows of Barbara and Cosme will dissipate near Revillagigedo 
Islands through mid week. Rough seas across the Revillagigedo 
Islands will persist into early Thu. Looking ahead, an area of 
low pressure is forecast to develop later this week south of 
southern Mexico. Environmental conditions appear conducive for 
some gradual development of this system, and a tropical 
depression could form late this week or over the weekend. there
is a medium chance of tropical cyclone formation through 7 days.

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

A weak pressure gradient remains over the area resulting
generally in gentle to moderate southerly winds south of the 
monsoon trough, and light to gentle winds to the north of it. 
Cross-equatorial southwest swell is producing moderate seas 
across the offshore forecast waters. Moderate to fresh winds NE
winds are across the Gulf of Papagayo and downwind to near 87W
based on latest scatterometer pass. 

For the forecast, moderate to fresh winds are expected in the
Papagayo region through Thu night. Winds may increase to strong 
speeds on Fri. Elsewhere, gentle to moderate winds will persist S
of the monsoon trough while light to gentle winds are expected 
to the N of it through Wed. Moderate seas in cross equatorial 
swell will also continue through Wed. Winds may increase to fresh
speeds S of the monsoon trough on Thu, with seas likely building
to 8 ft. Abundant deep tropical moisture will persist across the
region maintaining a high chances of additional showers and 
thunderstorms well into the week as a broad low pressure gyre 
forms west of Central America.

...REMAINDER OF THE AREA...

Please read the Special Features section for information on
Hurricane Barbara and Tropical Tropical Storm Cosme forecast to
be a hurricane tonight.

Outside of the areas impacted by Cosme, a ridge dominates the
waters N of 15N and W of 120W supporting gentle to moderate 
winds. Moderate to locally fresh NE winds are occurring from 10N
to 15N W of 120W due to the pressure gradient between the
southern periphery of the ridge and the ITCZ/Monsoon trough.  
Seas to 8 ft persist from 10N to 15N west of 135W in a combination
of moderate tradewind-induced waves and longer period SW swell. 
An area of fresh to locally strong southerly winds is observed S 
of the monsoon trough between 110W and 122W. Seas are 8 ft within
these winds. Moderate seas are noted elsewhere.

For the forecast, little change is expected through the middle of
week outside of the area near Cosme as described in the Special 
Features section. Looking ahead, SW winds will increase into the 
monsoon trough east of 110W later in the week, with building 
seas. This pattern is associated with broad low pressure that may
develop off Central America and the far eastern Pacific. 
Environmental conditions appear conducive for some gradual 
development of this system, and a tropical depression could form 
late this week or next weekend. 

$$
GR