000
AXPZ20 KNHC 180322
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
320 UTC Sat Nov 18 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.

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from 09N84W to 10N92W to 09N105W 
where it transitions to the intertropical convergence zone, and 
extends through 11N125W to beyond 11N140W. Scattered moderate
isolated strong convection is noted from 09N to 11N W of 137W. 
Scattered moderate convection is noted from 11N to 14N between 
123W and 127W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

High pressure is forecast to build in from the N on Sat with
current gentle to moderate northerly winds across the offshore 
waters W of Baja California, becoming moderate to fresh NW to N 
winds and building seas of 6-7 ft N of 25N Sat morning through 
late Sun.

Gulf of Tehuantepec: A final pulse of strong northerly drainage 
flow, with seas building to a max of 9 to 10 ft, are forecast 
late tonight into early Sat morning, diminishing afterward as the
high pressure over the eastern slopes of the Sierra Madre 
mountains weakens. Another strong cold front will enter the Gulf 
of Mexico late Sat, followed by strong high pressure building 
into northeast and central Mexico through Sun. This will support 
a return of strong gap winds in the Gulf of Tehuantepec by early 
Sun, reaching gale force Sun afternoon through Mon morning. A 
gale warning is now in effect for the area in the latest High 
Seas forecast. NWP guidance indicates winds of 35-40 kt and 
building seas of 14-15 ft by Sun night. 

Gulf of California: Strong high pressure building north of the 
area over the Great Basin will support fresh to strong NW winds 
across the northern Gulf of California by mid-day Sat, spreading 
into the central and southern portions of the gulf late Sat into 
Sun, before diminishing late Sun. Seas are forecast to build to 6
or 7 ft across the central gulf early on Sun.

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 through the middle of 
next week with seas building to 5 ft downstream near 10N87W. 
  
Light and variable winds, and 3 to 5 ft seas, are expected 
elsewhere to the N of 09N, while moderate to locally fresh 
southerly winds, and 4 to 7 ft seas, are forecast S of 09N 
through the middle of next week. 

REMAINDER OF THE AREA...

A pair of 1017 mb surface lows are centered near 28N132W and 
28N128W. The associated dissipating front enters the forecast 
waters near 30N128W and extends to 20N138W. Earlier ASCAT-A and 
ASCAT-B passes from 1800-1900 UTC today indicated NE winds of 20 
to locally 25 KT N of 30N with lighter winds in the discussion 
area. A pair of altimeter passes showed 8 to 9 ft seas in the 
wake of the front. The complex lows are forecast to drift in 
place and weaken significantly as the front dissipates by early 
Sat. 

Strong SE to S return flow will develop across the NW waters N 
of 27N W of 138W by Sat night, in advance of the next cold front
forecast to approach the far NW corner of the area Sun night. 
The front will move slowly with the strong S to SW flow persisting
over the NW waters on Mon. At that time, expect fresh to strong 
winds and seas of 8 to 11 ft covering roughly the waters N of 
24N W of 136W.

Farther S and N of the ITCZ/Monsoon trough, expect gentle to 
moderate trade winds and 4 to 6 ft seas through Sat, with moderate
to fresh trades and seas of 6 to 7 ft by Sat evening into Sun.

$$
Cobb