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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 241610

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Fri Nov 24 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 1200 UTC surface analysis and satellite imagery through 
1500 UTC.


A gale warning remains in effect for Gulf of Tehuantepec through 
1500 UTC. Minimal gale force winds continue cross the Gulf of 
Tehuantepec and downstream to near 14.5N95.5W with seas of 8 to 
12 ft. Winds are expected to diminish below gale force by late 
morning today, and to 20 kt or less late Sat morning. The NE 
swell generated by this gap wind event is mixing with long-
period cross equatorial SW swell, with seas 8 ft or higher well 
downstream of the Gulf of Tehuantepec along 09N between 94W and 
100W. Expect winds of 20 kt or less and seas of less than 8 ft 
only briefly on Sat afternoon. Strong N winds are forecast to 
resume again on Sat night, with gale conditions expected by mid-
day Sun. The latest computer model guidance is suggesting 
another 30 to 40 kt gap wind event on Sun night, with seas 
building to 16 or 17 ft by early Mon morning. Gale conditions 
should persist through Mon.


The monsoon trough extends from 09N84W to 08N90W to 07N101W. The
ITCZ continues from 07N101W to 11N117W to 10N130W to 09N135W to 
beyond 10N140W. Scattered moderate to strong convection is 
occurring from 05.5N to 10N E of 85.5W to the coast, and from 
07N to 11N between 117W and 134W. 



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

A weak ridge continues across the offshore waters of Baja 
California producing mainly light to gentle NW winds and seas of 
3 to 4 ft. Seas will begin to build late this morning through 
this afternoon in NW swell, and peak at 4 to 7 ft at 13 to 15 
seconds across the waters W of Baja tonight, then subside some 
on Sat into Sun. Long-period NW swell in the form of 7 to 9 ft 
seas will reach 30N120W by early Mon morning, and spread S 
across the offshore forecast waters W of Baja with 8 to 13 ft 
seas at 17 to 19 seconds Mon night and Tue.

Winds will increase very slightly over the weekend, mainly due 
to daytime heating. However early on Monday, stronger high 
pressure will begin to build across the region from the NW and 
act to increase NW winds to 20-25 kt across the waters N of 26N, 
including the Sebastian Vizcaino Bay, by the late afternoon and 
evening hours.

Gulf of California: Overnight scatterometer data indicated 
gentle to locally moderate winds across the entire Gulf. This 
flow will continue through tonight. The pressure gradient will 
relax further, with light and variable winds expected through 
Mon. Strong to near gale force NW flow is expected to develop 
across the northern Gulf Mon night, with fresh to strong winds 
spreading southward across the central and southern portions of 
the Gulf through Tue night. Seas will quickly build to around 8 
ft across the northern Gulf by Tue morning and then 6-8 ft 
through central portions by Tue night. 


Fresh to locally strong NE winds are occurring across and 
downstream of the Gulf of Papagayo this morning, with the 
assistance of the nocturnal drainage flow. Seas have built to 6-
7 ft downstream of the gulf. Expect a typical nocturnal maximum 
of around 25 kt across the region through early Mon morning, 
diminishing to 15-20 kt by mid afternoon. Seas will maximize to 
around 7 ft each morning near sunrise. Moderate to locally fresh 
NE winds are expected across the Gulf of Fonseca each night 
through Mon. 

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


A stationary front is located just NW of the discussion area 
near 31N141W. An elongated surface low will develop along the 
front just W of the area by this evening then move NE of the 
area tonight with the associated cold front entering the 
forecast waters. The front is forecast to reach from 30N136W to 
22N140W tonight, and extend from 30N129W to 20N139W by Sat 
night. Fresh to strong southerly winds are expected ahead of the 
front, but mainly N of 26N. A reinforcing or secondary cold 
front will reach the far NW corner of the area by Sat morning 
followed by fresh to strong NW winds and seas up to 10 or 11 ft.
The fronts are forecast to merge on Sun as they move eastward 
and approach 125W.

Overnight altimeter data indicated seas of 10 to 14 ft from 20N 
to 27N W of 134W while seas of 8 ft or greater in long period NW 
swell are propagating across the waters NW of a line from 
30N121W TO 12N137W TO 12N140W. This swell event will begin to 
subside, with seas 8 ft or greater mainly S of 15N and W of 125W 
by late Sat. At that time, another pulse of NW swell is 
expected to reach the far NW waters.