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Eastern North Pacific Tropical Weather Discussion



654 
AXPZ20 KNHC 210330
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
202 UTC Tue Aug 21 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
0215 UTC. 

...TROPICAL WAVES...

A tropical wave along 96W is moving W around 15 kt. Scattered 
moderate and isolated strong convection is present from 06N to 
11N between 93W and 97W. 

A tropical wave along 116W-117W is moving W around 10 kt. 
Scattered moderate and isolated strong convection is found from 
07N to 14N between 111W and 120W.

A tropical wave along 128W-129W is moving W around 5 kt. 
Scattered moderate and isolated strong convection is seen within 
60 nm either side of a line from 17N125W to 13N134W.

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

The monsoon trough extends from 11N74W to 08N98W to 11N115W to 
12N125W. The ITCZ extends from 10N133W to beyond 09N140W. 
Scattered moderate and isolated strong convection is observed 
from 07N to 11N between 98W and 107W and from 07N to 11N between 
W of 133W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

A surface ridge across the NE Pacific extends SE from a 1030 mb 
high near 45N138W to enter the forecast waters near 32N130W, 
then onward to near the Revillagigedo Islands. This ridge will 
support a weak to modest pressure gradient across the offshore 
waters of Baja California. Gentle to moderate NW winds are
expected through Wed before the ridge strengthens slightly and 
the pressure gradient tightens across Baja California Norte Thu 
and Fri. Seas will generally remain in the 4-5 ft range through 
Wed. Surface troughing over the Baja Peninsula will maintain a 
generally light wind regime over the Gulf of California through 
Sat night, and allow for afternoon sea breezes and nocturnal 
land breezes to dominate.

Strong N to NE gap winds will affect the Gulf of Tehuantepec Tue 
night through Thu night, and are forecast to peak near 30 kt 
late Wed night. Seas of 4 to 6 ft during the daytime could build 
to near 8 ft each of these nights, and 8-10 ft late Wed night.

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

The monsoon trough will linger near 09N during the next few 
days. Winds on both sides of the trough axis will generally be 
light to moderate. The main exception to this will be over the 
Gulf of Papagayo, where moderate to fresh offshore winds will 
pulse to locally strong each night. Seas are expected to remain 
6-7 ft downstream of Papagayo during this time.

REMAINDER OF THE AREA...   

Elsewhere, the pressure gradient between ridging across the 
northern waters and the ITCZ will support gentle to moderate 
trades and 4-7 ft seas in mixed swell N of the ITCZ and W of 
120W through the middle of this week.

Sea heights will be relatively low for most of the forecast area
this week. Mixed SE and SW swell has produced 8 ft seas S of 02S
and W of 112W. This area of seas will continue until Tue morning
before subsiding to less than 8 ft. A much more robust round of 
long period swell could arrive from the Southern Hemisphere 
toward the end of this week and cause seas near the Equator to 
begin building on Sat.

$$
CAM