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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 230322
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Thu Nov 23 2017

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
0315 UTC.

...SPECIAL FEATURE...

Gulf of Tehuantepec Gale Warning: Gale force NW to N winds were 
indicated earlier today southward across the Gulf of Mexico W of
95W behind a cold front now pushing through the Isthmus of 
Tehuantepec. NWP model and gridded marine forecast data suggests
Gale force northerly winds are sweeping through the Chivelas 
Pass and into the Gulf of Tehuantepec. These winds are forecast 
to peak at 35 to 45 kt later tonight into early Thu. Gale force 
winds will spread farther downstream of the coast to about 13N, 
and seas building to 16-17 ft, with winds then diminishing 
slightly early Thu afternoon. Minimal gale conditions will then 
persist through mid morning on Fri then diminish to 20 kt or less
late Sat morning. The resultant NE swell will propagate SW, 
mixing with long-period cross equatorial swell, with seas 8 ft or
higher well downstream of the Gulf of Tehuantepec along 08N 
between 94W and 102W on Fri evening before beginning to subside. 
Looking ahead, Strong N winds are forecast to resume again on Sat
evening with Gale conditions from sunrise Sun and continuing 
through sunrise on Tue. 

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from low pres near 11N76W 1010 MB 
across Panama to 10N90W to 10N102W, then transitions to ITCZ 
near 10N102W and continues through 10N115W to 08N130W to 
09N140W. Scattered moderate convection was across far eastern 
portion of the basin from 07N to the coast of Panama between 80W
and 84W. Scattered moderate to strong convection was noted 
within 60 NM of a line from 20N135W to 18N136W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See Special Features paragraph above for information on the 
developing Gulf of Tehuantepec Gale Warning. 

A NW to SE orientated ridge axis extends from a 1020 MB high 
near 29N128W through 18N110W, or about 250 nm seaward of the 
Pacific coast of Mexico. This ridge will only be interrupted by a
weak surface trough extending S from the central Baja Peninsula 
to near 20N112W, and is expected to persist through Fri night 
before filling. Expect seas of 3 to 4 ft seas at 12 seconds W of 
Baja through Thu morning, except near 2 ft nearshore, then 
building in new NW swell at 14 to 15 seconds Fri, peaking at 4 to
7 ft across the waters W of Baja Fri night. Seas will then 
gradually subside some Sat into Sun. Long- period NW swell in the
form of 7 to 9 ft seas will reach 30N120W on Sun night, and 
spread S across the waters W of Baja with 8 to 13 ft seas at 17 
to 19 seconds forecast W of Baja late Mon night.

Gulf of California: Moderate to locally fresh NW flow prevails 
across across all but southern portions of the gulf this evening
as high pressure is building across N Mexico behind a cold 
front. Winds will diminish slightly tonight through Thu night as
the ridge shifts SE. The pressure gradient will then relax 
further, with light and variable winds on Fri through Mon. Strong
to near gale NW flow expected N of 30N late Mon night, with gale
conditions possible on Tue afternoon with seas building to 10-11
ft across the long fetch waters. 

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

Gulf of Papagayo: Fresh to locally strong NE nocturnal drainage 
flow forecast to begin on Thu night into early Fri afternoon, and
then resume on Fri night and continue through Tue with strong 
winds are expected to reach as far SW as 09N91W.

Light and variable winds, and 3 to 5 ft seas, are expected 
elsewhere through Sun to the N of the monsoon trough which has 
been meandering between 09N and 11N, while moderate southerly 
winds, and 3 to 6 ft seas, are forecast S of the monsoon trough.

REMAINDER OF THE AREA... 

A NE to SW aligned ridge will meander from 29N128W to 25N134W 
for the next several days. SW winds currently across the waters N
of 30N W of 135W have moderated in advance of a cold front has 
entered the far NW portion of the area. This front is expected to
move to near 30N138W to 27N140W and stall through Fri as 
elongated low pressure develops along the front. 

The front will usher in long period NW swell into the far NW
corner of the area tonight and Thu with seas building to 9 to 15
FT at 14 to 16 seconds late tonight. This NW swell, in the form
of 8 to 11 ft seas at 12 to 17 seconds, will propagate across 
the waters W of a line from 32N122W to 14N140W on Thu night 
before beginning to subside. 

Another cold front will move E in to the area reaching from 
32N133W to 25N140W early Sat with 8 to 11 ft seas at 12 to 17 
seconds in the wake of the front. 

$$
Cobb

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Page last modified: Thursday, 23-Nov-2017 03:22:20 UTC