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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 200949
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Nov 20 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 0600 UTC surface analysis and satellite imagery through 
0945 UTC.

...SPECIAL FEATURE...

Gulf of Tehuantepec Gale Warning: Gale force 30 to 40 kt 
northerly winds will continue through sunrise this morning, with 
maximum seas of 17 ft downstream of the gulf waters near 
14N95.5W just before sunrise. Winds will gradually diminish to 
20 kt or less on Tue morning. The associated NE swell will 
propagate SW mixing with long-period cross-equatorial swell, 
resulting in an area of 8 ft and greater seas of across the 
waters from roughly 09N to 13N between 94W and 103W on Mon 
night, with a small area of 8 ft seas subsiding near 10N104W on 
Tue morning. Strong N winds are expected to resume on Wed 
afternoon, with gale conditions on Wed evening through Fri 
morning with max seas of 15 ft near 13N96W on Thu.      

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends W-SW across the southern Gulf of 
Panama from 08N78W to 06N90W to 08N104W where scatterometer 
winds indicate a transition to an ITCZ, which continues W-NW to 
11N114W to 10N131W to beyond 11N140W. Scattered moderate 
isolated strong convection is noted within 240 nm of 11.5N121W, 
and along the ITCZ within 75 nm either side of a line from 
09N128W to 14N140W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See Special Features paragraph for Gulf of Tehuantepec Gale 
Warning. 

A NW to SE orientated ridge just beyond 250 nm seaward will 
maintain moderate NW flow W of the Baja Peninsula through mid 
morning when the pressure gradient will relax, supporting light 
northerly winds through late wed when a trough will form SW from 
the central Baja Peninsula to near 22N116W and continue through 
early Fri before filling. Expect seas in the 3 to 5 ft range 
through Thu building to 5 to 7 ft N of 25N late in the week.  

Gulf of California: Moderate NW flow will diminish to a light 
breeze later this morning and continue through Tue morning when 
moderate to locally fresh conditions will develop, and continue 
through early Wed. Light to moderate NW flow expected on Thu and 
Fri becoming light and variable on Fri night.   

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

Gulf of Papagayo:  Moderate to locally fresh NE drainage winds 
are forecast during the overnight hours tonight, then light 
drainage flow expected during the overnight hours through Thu 
night, with fresh to locally strong nocturnal drainage 
possible on Fri and Sat nights.

Light and variable winds, and 3 to 5 ft seas, are expected 
elsewhere to the N of the monsoon trough which has been 
meandering between 09N and 11N, while moderate to locally fresh 
southerly winds, and 4 to 7 ft seas, are forecast S of the 
monsoon trough this week.  

REMAINDER OF THE AREA...

A NE to SW aligned ridge will meander from 32N125W to beyond 
20N140W for the next several days. Strong to occasionally near 
gale force southerly winds currently across the waters N of 28N 
W of 138W, will spread E across the waters generally W of a line 
from 32N130W to 22N140W through late tonight before the pressure 
gradient relaxes. Associated seas are expected to build to 8 to 
12 ft across the waters S of 30N, while 10 to 14 ft seas are 
forecast from 30N to 32N. A series of cold front will approach, 
but stall just W of 140W through Tue night. Model guidance is 
suggesting a cold front will arrive at 32N140W on Wed, and stall 
from 32N136W to 23N140W on Thu, with seas building 12 to 17 ft W 
of the front through Thu. 

Moderate anticyclonic flow expected across the tropics N of the 
ITCZ and W of 120W through the middle of next week, with seas of 
4 to 7 ft. Long period NW swell will propagate E across the 
discussion waters W of 120W from mid to late week, and subside 
over the upcoming weekend.

$$
Nelson

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Page last modified: Monday, 20-Nov-2017 09:50:13 UTC