000
AXPZ20 KNHC 212132
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2107 UTC Fri Apr 21 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 1800 UTC surface analysis and satellite imagery through
2130 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

A surface trough extends from 07N83W to 06N90W to 05N100W. The 
ITCZ extends from 07N116W to 05N130W to 04N140W. Scattered 
moderate isolated strong convection is observed within 120 nm 
either side of the itcz between 118W and 138W. Scattered moderate
convection was noted within 120-180 nm either side of the trough
between 85W and 99W. 

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A ridge axis extends from a 1024 MB high near 31N128W southeast
through 24N120W to 15N100W. Scatterometer data shows fresh 
northwesterly winds north of 25N, which are expected to diminish 
to moderate tonight. Associated seas of 8 to locally 11 FT will 
subside to 5-7 FT by late Saturday. Large NW swell will reach 
29N120W on Sunday and spread southward across the waters north of
25N by late Monday then subside. A tightening pressure gradient 
will produce strong NW winds in waters north of 29N east of 121W 
on Tuesday.

Gulf of California: Gentle NW flow is expected for most of the 
gulf through Saturday, except for variable winds setting up 
around a surface low north of 30N Saturday night and Sunday. 
Fresh to locally strong nocturnal SW winds are expected near 
30N114W each night from Sunday through Tuesday.

Gulf of Tehuantepec: A significant gap wind event is expected to
begin overnight Sun, rapidly increasing to 30 KT by sunrise 
Monday, then quickly diminishing later Monday. Blended NWP 
gridded forecasts show winds not reaching gale force per trends 
in the raw NWP guidance. 

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

Light to gentle winds in mostly onshore flow is expected during 
the day, becoming offshore at night. Combined seas of 3 to 5 FT 
in mixed SW and NW swell will prevail for the next several days.
 
REMAINDER OF THE AREA...
  
A surface ridge along about 130W continues to block the eastern 
advance of cold fronts. Strong southwest winds ahead of a cold 
front currently along 30N138W to 29N140W will shift northward 
later tonight as the front moves east and weakens. The front 
will stall from roughly 30N130W to 25N140W late Saturday and
dissipate Sunday. Large nw swell associated with the front will 
build seas of 8 to 12 FT in NW waters through early Sunday. 
Expect the NW swell to propagate east, reaching from the northern
Baja Peninsula to 07N140W Sunday, and then quickly subside early
next week. Strong NW winds are expected N of 28N east of 124W by
the middle of next week.
  
$$
COBB