000
AXPZ20 KNHC 130924
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Fri Oct 13 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
0900 UTC.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from 09N84W to 09N90W to 10N100W to
1008 mb low pressure near 12N111W to 10N116W to 11.5N123W to 
11N140W. Scattered moderate isolated strong convection is N of 
03N E of 79W, including the Gulf of Panama. Similar convection is
noted from 10N to 14N between 110W and 116W. Scattered moderate 
convection is from 08N to 11N between 103W and 110W, and from 10N
to 12N between 120W and 124W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A surface ridge extends across the waters off Baja California. 
The pressure gradient between the ridge and a trough over the 
Gulf of California is supporting gentle to moderate NW winds in 
the offshore waters of Baja California. Seas of 7 to 9 ft in 
northerly swell are spreading across forecast zone PMZ011, with 
seas 6-7 ft in the Sebastian Vizcaino Bay. Seas of 4 to 6 ft are
noted elsewhere. The ridge will remain in place through Saturday
will little change in winds. By Saturday evening, expect seas of
5-7 across most of the offshore waters W of 110W. On Sunday, 
marine guidance suggests increasing winds and building seas near 
the Revillagigedo Islands in association with a developing low 
pressure. 

High pressure across the eastern slopes of the Sierra Madre
Mountains in Mexico continues to induce strong northerly gap 
winds across the Gulf of Tehuantepec. The strong winds over the 
Gulf of Tehuantepec will pulse to near gale force during the 
overnight and early morning hours the next few days. Model 
guidance indicates winds will further increase to minimal gale 
force Monday night through early Wednesday morning as high 
pressure builds behind a front moving into the Gulf of Mexico. 
Seas downstream from the gulf will build to 8-11 ft during the 
times of maximum winds through Monday. Seas of 12-14 ft are 
expected with the gale force winds. 

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR...
    
Moderate to fresh offshore winds will develop across the Papagayo
region Sat and continue through Mon with seas of 5-6 ft. Light 
and variable winds and seas of 4 to 5 ft seas prevail N of 09N, 
with little change expected through Saturday morning. Seas will 
increase slightly through the weekend as cross-equatorial SW 
swell reaches the region. Gentle to moderate SW to W winds and 5 
to 6 ft seas are currently observed across the area S of 09N, 
with a slight increase in seas expected through the weekend with 
the arrival of SW swell. 

REMAINDER OF THE AREA...

Unusually strong high pressure of 1042 mb centered NW of the 
area near 44N146W extends a ridge southeast to near 20N115W. The 
pressure gradient between the ridge and the monsoon trough is 
producing an area of fresh to strong NE-E winds north of 22N 
west of 125W, with moderate to fresh NE winds from 13N-22N W of 
130W. Seas of 9-14 ft in northerly swell are noted across the N 
waters N of 24N W of 125W based of latest altimeter passes with
seas of 8-11 ft covering the waters NW of a line from 30N117W to
25N120W to 22N130W to 22N140W. Winds are forecast to diminish to
20 kt or less across the northern forecast waters on Saturday as
the strong high pressure moves SE and weakens some. Seas will
gradually subside, but seas of 8-9 will continue to affect much
of the waters N of 20N W of 120W by Saturday evening. In addition,
large swells from the Southern Hemisphere will continue to propagate
across the south-central waters, particularly S of 12N between 
105W-115W over the next couple of days. 

$$
GR