000
AXPZ20 KNHC 201533
TWDEP 

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

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

A surface trough extends from the Pacific coast of Costa Rica 
near 09N84W to 04N100W. A weak ITCZ extends from 02N116W to 
04N135W. Scattered moderate isolated strong convection is found 
from 04N to 07N east of 91W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

High pressure centered near 34N128W extends a ridge SE to near 
the Revillagigedo Islands. Scatterometer data at 0426 UTC showed 
an area of 25 to 28 kt winds in Sebastian Vizcaino Bay, and a 
larger area of 20 to 25 kt winds north of 25N and west of the 
Baja Peninsula to 120W. The high will shift north-northeastward 
through Friday morning, allowing winds to diminish below 20 kt. 
Combined seas west of Baja will increase to 9-10 ft tonight in N 
to NW swell, then subside to 7-8 ft Saturday as the NW winds 
continue to weaken across the area. The southern portion of a 
cold front moving into Southern California will reach Baja 
California Norte early Monday, and swell associated with the 
front will cause seas to build to between 8 and 10 ft west of 
Baja California Norte late Sunday night through Tuesday.

Gentle to moderate NW winds are expected in the Gulf of 
California through Friday, becoming light to gentle this weekend 
with seas subsiding to 1-2 ft by Sunday. Fresh to locally strong 
winds are possible north of 29N Monday through Wednesday. 

The next significant gap wind event for the Gulf of Tehuantepec 
is expected to begin Sunday evening as a cold front pushes south 
along the Sierra Madre Oriental. Model guidance suggests strong 
to minimal gale force winds Sunday night through Monday morning. 
High pressure behind the front will shift eastward by Tuesday, 
allowing winds and seas to diminish.
  
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR...

Light to gentle winds, onshore during the day and offshore at 
night, and combined seas of 3 to 5 ft in mixed SW and NW swell 
will prevail through the next several days, associated with a 
broad trough of lower pressure residing over the region.

REMAINDER OF THE AREA...
  
High pressure centered near 34N128W will shift north-northeast 
ahead of an approaching cold front. Southerly winds ahead of the 
front will reach 25 kt Friday morning. The front will push into 
far NW waters Friday, then stall and weaken from 30N130W to 
22N140W by Saturday night. NW swell associated with the front 
will sweep into the area Friday night and Saturday with max seas 
building to 12 ft, then subside to 8-9 ft by Sunday. Seas will 
also remain greater than 8 ft just W of Baja to the N of 23N and 
E of 125W through Tuesday morning. Moderate to fresh trades will 
prevail elsewhere north of the ITCZ west of 120W through the 
beginning of next week with little change. Trade wind waves in 
this area will help maintain seas above 7 ft through the middle 
of next week.

$$
Mundell