AXPZ20 KNHC 270831
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed Sep 27 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
A tropical wave is along 85W north of 06N, moving west at 5 to
10 kt. No significant convection is noted near the tropical wave
axis at this time.
A tropical wave is analyzed along 126W from 04N to 17N, moving W
at 10 to 15 kt. Scattered moderate convection is active from 10N
to 13N between 125W and 127W. A recent scatterometer satellite
pass shows a well defined trough at the surface along 126W, with
moderate to fresh easterly winds farther north between the trough
and the subtropical ridge to the north.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough extends from 09N83W to 09N115W. Segments of
the ITCZ extend from 09N115W to 08N123W, and from 06N127W to
09N140W. Scattered moderate convection is noted within 90 nm
south of the ITCZ west of 135W.
...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
A recent scatterometer satellite pass indicated moderate to fresh
NW winds persisting off Baja California, between high pressure
to the northwest and a trough to the east. Wave heights will
build off Baja California due to the arrival of long-period NW
swell. A recent altimeter pass along with a couple of the ship
observations showed combined seas are already 10 to 12 ft mainly
off Baja California Norte. Gentle to moderate breezes farther
south and in the Gulf of California, with 4 to 6 ft seas in open
waters with mixed swell.
For the forecast, the moderate to fresh NW winds will persist
off Baja California north of Cabo San Lazaro through the morning
between high pressure north of the area and a trough over the
Gulf of California. Winds will then gradually diminish through
Fri as the ridge shifts NW. Seas of 8 to 12 ft in NW swell will
persist through Thu offshore Baja California before slowly
subsiding Fri through Sat. Farther south, moderate to fresh N gap
winds will pulse to strong across the Gulf of Tehuantepec
tonight. Looking ahead, expect fresh westerly gap winds over the
northern Gulf of California will start Fri afternoon, ahead of an
approaching cold front, possibly reaching near-gale force by Sat
...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA,
COLOMBIA, AND WITHIN 750 NM OF ECUADOR...
Light and variable breezes are evident off northern Central
America, north of the monsoon trough. Gentle S to SW breezes are
noted farther south, except moderate winds S of 04N. Combined
seas are 4 to 5 ft across the region with southerly swell.
For the forecast, gentle to moderate winds will prevail to the north
of 05N with seas 5 ft or less through Sun night, with moderate SW
winds farther south. Seas south of 05N will build to 6 to 9 ft
in southerly swell through Fri evening, with seas highest to the
SW of the Galapagos.
...REMAINDER OF THE AREA...
The remnant trough that was T.C. Fourteen-E is passing west of
the area. A recent scatterometer satellite data indicated mostly
fresh winds are still accompanying the low within 180 nm in the
northern semicircle, implying a large area of rough seas of 9 ft
there. Farther north, altimeter satellites passes continue to
indicate of long- period NW swell crossing 30N and moving into
the discussion waters. To the south, satellite altimeter data
also showed seas to 8 ft crossing the equator between 110W and
120W. This is part of a large area of southwest cross-equatorial
southerly swell moving into the waters south of 03N and west of
For the forecast, high pressure north of the front will increase
the pressure gradient to the west of 125W, and freshen the winds
through Thu. Large, long-period NW to N swell will continue to
propagate into the waters north of 22N, then cover the area north
of a line from Baja California Sur to 10N120W to 10N130N by late
today. Meanwhile high pressure will build north of the area,
supporting fresh to strong trade winds by Wed from 10N to 20N
west of 120W, with combined seas building to 13 ft in a mix of
NW swell and shorter period NE to E wind waves. Farther south,
southerly swell will continue to move across the equator,
supporting combined seas of 8 to 9 ft south of 03N and west of
115W by Thu.