000
AXPZ20 KNHC 211515
TWDEP 

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

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

A surface trough extends from 09N84W to 06N90W to 05N100W. The 
ITCZ extends from 03N114W to 05N120W to 04N140W. Scattered 
moderate isolated strong convection is observed within 60 nm 
either side of a line from 03N114W to 06N123W to 06N140W. 

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A ridge axis extends from NW to SE across the offshore waters 
west of 111W. Scatterometer data shows fresh northwesterly winds 
north of 25N, which are expected to diminish to moderate NW 
winds tonight. Associated seas of 8 to 9 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 strong nocturnal sw winds are expected near 30N114W on 
Sunday, Monday and Tuesday nights.

Gulf of Tehuantepec: A significant event is expected to begin on 
Sun evening, rapidly increasing to 30 kt or more Sunday night, 
then quickly diminishing Monday morning. Previous GFS model 
guidance has been indicating a brief period of minimal gale fore 
winds around 0600 UTC, but the trend over the past few model 
runs has been lower, toward 30 kt as a maximum value.

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 approaching the area will shift northward tonight as the 
front moves east and weakens. The front will stall from roughly 
32N128W to 25N140W on Saturday. 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.
  
$$
Mundell