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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 231617

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Sat Jun 23 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 1200 UTC surface analysis and satellite imagery through 
1500 UTC. 


The monsoon trough extends from 10N75W TO 10N93W to a 1010 mb 
low pressure near 14.5N105W to a 1007 mb low pressure near 
12.5N116W to 09N122W. The ITCZ continues from 09N122W to 08N130W 
to 10N140W. Scattered to locally numerous moderate to strong 
convection noted within 240 nm of the coasts from Nicaragua to 
Colombia. Otherwise, scattered moderate to strong convection is 
from 04N to 09N between 91W and 100W, from 08N to 18N between 
99W and 110W, from 09N to 14N between 112W and 120W and from 07N 
to 15N W of 130W.



NW winds have diminished early this morning across the waters 
west of Baja California, as a broad surface trough along the W 
coast of the peninsula shifts westward across the NE Pacific 
waters. Winds west of the peninsula will become variable less 
than 15 kt through the weekend. However, southerly winds inside 
the Gulf of California have increased quickly overnight, and are 
forecast at 20-30 kt to the north of 30N this morning, and fresh 
to strong elsewhere N of 26N this morning. Seas across this area 
will increase to 6-9 ft later this morning through afternoon, 
before winds and seas begin to slowly subside through late  

Further south, long period cross-equatorial SW swell has moved 
into the regional waters overnight and will affect the waters 
from central Baja California to Central America through Monday. 
5 to 7 ft seas off of Southern Mexico this morning will build to 
6-8 ft by Sun morning before slowly subsiding late Sun night and 


The monsoon trough will meander between 09N and 13N the next 
several days. Light to gentle winds will prevail north of the 
monsoon trough, with gentle to moderate S to SW winds expected 
south of the trough axis. Long period cross-equatorial SW swell 
is across southern forecast waters with seas to 8 ft. The swell 
will propagate further north to the offshore waters of Costa 
Rica and Colombia today and then will gradually subside through 


High pressure north of the area centered near 36N141W extends a 
ridge SE to near the Revillagigedo Islands. Moderate to fresh NE 
to E winds prevail west of 130W with seas generally ranging 
between 5 to 7 ft. Gentle to moderate N to NE winds dominate the 
remainder of the basin north of the monsoon trough and west of 
120W. The high pressure center is forecast to shift NW and 
reorganize, which will freshen winds N of 25N and to the west of 
125W through Mon.

Typical northerly swell generated offshore of California is 
propagating into the northern waters this morning, and will 
build seas modestly to 8 ft north of 28.5N between 122W and 129W 
late tonight before seas subside to 6-7 ft Sun afternoon. The 
cross-equatorial southerly swell is also moving through the 
tropical waters south of 20N and west of 120W this morning, and 
will maintain seas 5-7 ft there through Mon.

A low pressure centered near 12.5N116W and embedded along the 
monsoon trough has an estimated pressure of 1007 mb. Model 
guidance shows this low emerging from the trough and drifting 
northward with a gradual increase in intensity through the 
weekend. Active thunderstorms will continue in the vicinity of 
this low through early next week before the low moves across 
cooler waters and begins to weaken considerably late Tue.

A 1010 mb low pressure is near 14.5N105W generating scattered 
moderate convection from 09N to 18N between 98W and 110W. Global 
models guidance indicate there is a good chance for this low to 
develop into a tropical cyclone SW of Mexico early next week.