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Eastern North Pacific Tropical Weather Discussion



636 
AXPZ20 KNHC 220915
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 0600 UTC surface analysis and satellite imagery through 
0915 UTC.

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

The monsoon trough extends W off the Caribbean coast of Colombia 
at 10N75W, and continues west across the extreme southwest 
Caribbean and across northern Costa Rica to the Pacific Coast of 
Costa Rica at 11N85W to 09N106W TO 11N123W where it loses 
identity. The monsoon trough resumes near 12N128W and extends 
southwest to 11N140W. Scattered strong convection is noted 
within 150 nm either side of a line from 13.5N89W to 12N98W. 
Isolated moderate to strong convection is observed elsewhere 
within the area bounded by 19N120W to 17N98W to 08N83W to 
04N110W to 09N127W to 19N120W. Scattered moderate convection is 
noted within 60 nm either side of a line from 10.5N130W to 
09N137W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

A ridge extending from 22N116W to 15N100W will gradually retract 
northwest as a surface low slowly develops near 13N106W on Sun 
night, and then tracks 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 
18N115W on Fri.

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 the 
weekend. 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 tonight through Mon night, with a strong northerly 
drainage event expected on Thu night with seas building to 9 ft.
The late week event may assist in the development of a surface
low near 12N95W late next week.  

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 Mon night. 

Light and variable winds are forecast elsewhere N of the monsoon 
trough which is meandering between 09N and 11N. Moderate 
southwest flow is forecast S of the monsoon trough through the 
middle of next week. Moderate to fresh southwest monsoonal flow 
is expected south of 10N late next week as a surface low begins
to develop near 13N93W on Thu, and then tracks northwest of the
area on Fri accompanied by tstms.   

REMAINDER OF THE AREA...   

A trough extends southwest from 20N125W to 11N128W with isolated 
strong convection flaring within 60 nm of the trough. The trough 
will move west of the area by the middle of next week.

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

$$
Nelson