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Eastern North Pacific Tropical Weather Discussion



229 
AXPZ20 KNHC 190900
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed Sep 19 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 
0900 UTC. 

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

The monsoon trough extends from 11N86W to 11N997W to 07N114W. A 
trough extends from 20N112W to 11N130W, and the ITCZ continues 
from there to 09N138W. Scattered moderate to strong convection 
is from 14N to 16N between 126W and 130W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

A surface trough over the Baja Peninsula will maintain gentle to 
moderate winds in the Gulf of California this morning, becoming 
fresh to locally strong southerly winds by afternoon in response 
to a ridge building into the area, then diminish Thu evening as 
the pressure gradient weakens. Active convection is observed in 
the southern Gulf of California from 23N to 26N between 108.5W 
and 110.5W, and model guidance indicates scattered thunderstorms 
are likely in the central Gulf today. High pressure NW of the 
area supports fresh NW winds W of the northern Baja peninsula, 
and seas are estimated to be 6-7 ft north of 27N.

A trough over the western Caribbean is enhancing northerly gap 
winds over the Gulf of Tehuantepec, with peak winds at night 
near 20 kt through Sun. Light to gentle variable winds will 
prevail elsewhere, with seas generally 4-7 ft in SW swell.

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

The monsoon trough will meander near 10N during the next several 
days, with mainly gentle winds expected on either side of the 
trough axis. Winds over the Gulf of Papagayo will pulse to 20 kt 
through Fri night. Scattered moderate to strong convection is 
observed south of Panama to 07N between 78W and 83W.

Cross-equatorial SW swell reaching the coast of Central America 
will persist into the weekend, with sea heights mostly 5-7 ft.

REMAINDER OF THE AREA...   

An elongated area of low pressure along a trough analyzed from 
20N112W to 14N124W will maintain fresh SW winds south of the 
trough axis between 110W and 120W. 

The gradient between high pressure N of 30N and lower pressures 
along the ITCZ is supporting fresh trade winds west of 130W, 
with 8 ft seas west of a line from 20N140W to 18N137W to 16N127W 
to 13N140W. Winds and seas will slowly diminish Thu and Fri as 
the pressure gradient weakens west of 120W.

$$
Mundell