000
AXPZ20 KNHC 061600
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Thu Apr 6 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
1545 UTC.

...SPECIAL FEATURE...

GULF OF TEHUANTEPEC GALE WARNING...

High pressure surging southward along the Sierra Madre Mountains
of Mexico has resulted in a very tight pressure gradient across
southeastern Mexico. This synoptic pattern is bringing minimal 
gale force north to northeast winds through the Isthmus of 
Tehuantepec, and over the Gulf of Tehuantepec as of this morning.
As the gradient tightens, these winds will increase to 40 kt 
early this evening with induced seas of 10-14 ft just downstream 
of the Gulf of Tehuantepec. The gradient is expected to slacken 
slightly by early Friday afternoon allowing for winds to briefly 
diminish to just below gale force. The north to northeast winds 
will once again increase to minimal gale force on Fri evening, 
then diminish to below gale force on Saturday, and continue to 
diminish to 20 kt or less by Sunday morning. Swell produced by 
this event will mix with northwest well to the southwest of the 
Gulf through with seas of 8-10 ft reaching to near 08N between 
94W and 100W by Saturday. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...  

The ITCZ axis extends from 04N96W to 03N110W to 02N120W to 
04N127W. It resumes at 04N130W to 02N140W. Scattered moderate to
strong within 240 nm north of the axis between 98W and 101W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

See special features above for details on the ongoing Gulf of 
Tehuantepec gale force gap wind event.

High pressure centered west of the area extends a ridge eastward
to near the Revillagigedo Islands. Outside of the Gulf of 
Tehuantepec region, gentle to moderate northwest to north flow 
will prevail across the offshore waters. Winds will strengthen 
over the offshore waters off the west coast of Baja California 
Norte early on Sunday.

Gulf of California: Gentle to moderate northwest winds will
prevail today before weakening slightly on Friday.

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

Gulf of Papagayo: winds will pulse to fresh to strong during the
late night and early morning hours each night through Sunday
night. These winds will expand northward to 12N and westward to 
near 88W Friday and Saturday.
 
Gulf of Panama: Moderate to fresh nocturnal flow is expected 
during the overnight hours each night through the weekend.
  
Elsewhere, light to gentle winds, and combined seas of 3 to 5 
ft will continue through Saturday. 

REMAINDER OF THE AREA...

A surface trough extending from 10N125W to 02N127 is moving west
at about 15-20 kt. Only isolated showers are noted within 60-90 
nm of trough. The trough will reach to near 133W by early Friday 
and to near 140W by early Saturday as depicted in the GFS 
moisture convergence guidance. The pressure gradient between high
pressure over the northern waters and lower pressure in the 
vicinity of the ITCZ is supporting gentle to moderate trades over
the trade wind zone. Northwesterly swell is propagating through 
the northwest waters, with seas in the 8 to 10 ft range northwest
of a line from 32N129W to 27N132W to 26N140W. Yet wave model 
guidance suggests that another set of northwesterly swell will 
propagate into the northwest waters beginning tonight. This swell
will peak seas to around 12 ft through Friday before beginning 
to slowly subside Friday night through Saturday. 

$$
Aguirre