000
AXPZ20 KNHC 150231
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sat Apr 15 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
0200 UTC.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...  
The northern Intertropical Convergence Zone axis extends from 
04N95W to 03N110W to 01N130W. A trough is embedded within the
ITCZ and extends from 05N122W to 00N123W.  Scattered moderate to
isolated strong convection is noted within 120 nm S of axis 
between 120W and 128W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A tight pressure gradient between high pressure over eastern 
Mexico and lower pressures south of the Tehuantepec region will 
continue to support fresh to strong northerly winds across the 
Gulf of Tehuantepec through early Sunday morning with the 
assistance of the nocturnal drainage flow.

A surface ridge extends into the offshore waters while surface 
low pressure continues along the Gulf of California and over
the northwest section of Mexico. A tightened pressure gradient 
between these two features continue to support fresh to strong 
NW winds offshore of Baja California Norte where seas are up to 
11 ft based on a recent altimeter pass. The pressure gradient is
forecast to relax as the high pressure moves northward and a cold
front approaches the NW corner of the forecast area. Winds will
diminish to 10-15 kt by late Saturday. However, NW swell will 
continue to support seas up to 8 ft off the Baja California 
Norte through late Saturday.

Light and variable winds with seas generally below 2 ft will 
prevail across most of the Gulf of California during the upcoming
weekend. Seas of 2-3 ft are expected near the entrance of the 
Gulf.

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

In the Gulf of Papagayo, fresh to locally strong drainage flow 
is expected to pulse at night tonight and Saturday. Seas are 
expected to build to 8 ft with these winds. 

In the Gulf of Panama, moderate to fresh northerly flow is 
expected during the overnight hours through the upcoming 
weekend. Seas will be in the range of 5 to 6 ft downstream of 
the Gulf.
  
Elsewhere, light to gentle winds and combined seas of 3 to 6 ft 
will change little through the weekend.

REMAINDER OF THE AREA...

A set of large period NW swell is reaching the offshore waters 
of Baja California, building seas to 11 ft. This swell event 
will affect the entire coast of Baja California by tonight, and 
the Revillagigedo Islands by Saturday morning with seas to near 8
ft. 

The next cold front is forecast to reach the northwest waters 
early Saturday afternoon, however fresh to strong S-SW winds in 
the 20-30 kt range ahead of the front will enter the region 
during the early morning hours. A new set of northwest swell 
associated with this front will build seas up to 11-12 ft in the
far northwest portion of the area Saturday. Seas will subside 
Sunday morning as the swell energy decays. The front will reach a
position from 30N136W to 26N140W by Saturday evening, and from 
30N128W to 25N140W by Sunday evening while beginning to weaken. 
Moderate to fresh northerly winds will follow the front. 

A 1028 mb high pressure located north of area near 35N130W
extends a ridge SE to near the Revillagigedo Islands. The 
pressure gradient between the ridge and lower pressures in the
vicinity of the ITCZ is allowing for generally fresh to strong 
northeast winds roughly from 07N to 20N west of 118W, with 
resultant seas of 8 to 10 ft as indicated by latest available 
altimeter data. The high pressure will move northward while 
weakening due to the approching cold front. As a result, the 
trades over the central and western portions of the forecast area
will weaken. Then, marine guidance suggests mostly gentle to 
moderate trades over those sections of the forecast region. Seas
within the area of the trades will be in the 8-9 ft range due to
a combination of NE windwave and NW swell. 

A trough is embedded within the ITCZ and extends from 05N122W to
00N123W. A cluster of moderate to strong convection was associated
with this trough on Friday as well as fresh to strong winds. 
Convection has diminished across that area during the last hours.
The trough and associated moisture will continue to move
westward.
  
$$
GR