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Eastern North Pacific Tropical Weather Discussion



049 
AXPZ20 KNHC 230345
TWDEP 

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1005 UTC Sat Sep 22 2018 

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 
0345 UTC.

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

The monsoon trough extends W off the Caribbean coast of Colombia 
at 10N76W, and continues northwest across the extreme southwest 
Caribbean and continuing across Nicaragua to the coast at 
13N88W, then turns southwest to 09N100W, then northwest to 
10N113W, then southwest to 09N126W, then northwest to beyond 
11N140W. Scattered moderate isolated strong convection is 
observed within 60 nm of the coasts of Central America and 
Mexico from 77W to 108W amd also within 120 nm of 06N87W. 
Isolated moderate to strong convection is observed elsewhere 
within the area bounded by 20N120W to 15.5N97.5W to 06N84W to 
07N132W to 20N120W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

A ridge extending from 21N116W to 19N108W will continue to 
gradually retract northwest as a surface low slowly develops 
near 13N105W on Sun night. The low will track northwest 
accompanied by tstms just beyond 250 nm seaward. However, gentle 
to locally moderate cyclonic winds will shift northwest through 
the offshore waters mostly seaward of 200 nm with the low 
reaching a position near 17N115W on Fri. By then southerly 
swells in the form of 7 to 9 ft seas will spread east across the 
far offshore waters near 19N112W. 

Moderate northwest flow is forecast west of the Baja California 
through early Mon, except becoming a fresh northwest breeze 
within 90 nm of the coast during the late afternoons and 
evenings.  

Gulf of California: Gentle to locally moderate variable winds 
forecast across the gulf waters north of 30N through Mon 
afternoon. Otherwise, light to gentle variable winds expected 
across the gulf waters through the middle of next week.

Gulf of Tehuantepec: Fresh to locally strong nocturnal flow 
forecast through late Mon, then resuming on Mon night through 
Wed night with seas building to 10 ft downstream near 15.5N95W. 
Another late week drainage event may assist in the development 
of a surface low near 09N99W on Fri.  

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

Gulf of Papagayo: Moderate to locally fresh east nocturnal 
drainage flow expected through Thu night with seas building to 
8 ft. 

Light and variable winds are forecast elsewhere N of the monsoon 
trough which is meandering between 09N and 12N. Moderate 
southwest flow is forecast S of the monsoon trough through the 
middle of next week increasing to moderate to fresh southwest 
monsoonal flow south of 10N late next week as a surface low 
begins to develop near 09N99W on Fri, and then tracks northwest 
of the area on Fri accompanied by tstms.   

REMAINDER OF THE AREA...   

A trough extends southwest from 20N127W to 12N135W with 
scattered moderate isolated strong convection flaring within 60 
nm of the trough. The trough will move west of the area by the 
early Tue.

A broad ridge continues across the subtropics accompanied by 
moderate to locally fresh anticyclonic flow south of 23N west of 
120W.

$$
Nelson