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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 220315

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Fri Jun 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 
0300 UTC. 


A tropical wave axis extending from 17N99W to 04N101W is moving 
west at 15 kt. Scattered moderate isolated strong convection is 
from 07N to 13N between 97W and 106W. An area of low pressure is 
expected to develop from this system by early next week, and a 
tropical cyclone may eventually develop from this feature south 
of Mexico.


The monsoon trough extends from coast of Costa Rica near 10N86W 
to 14N107W to 1011 mb low pressure near 13N106W to 08N122W. The 
ITCZ continues from 08N122W to 10N138W. Scattered moderate 
convection is within 120 nm either side of the convergence zone 
axis west of 114W.



Moderate NW winds west of Baja California will diminish today 
through Sat night, and a broad surface trough will prevail along 
the length of the peninsula through Sun morning. Southerly winds 
will increase east of the trough axis in the Gulf of California 
this weekend, becoming fresh to strong southeasterly N of 29N 
Sat afternoon, continuing into early Sun morning. Seas in the 
northern Gulf of California to build to 6-8 ft by Sat night, 
then subside Sun along with a decrease in surface winds. Long 
period cross-equatorial SW swell will reach the waters off 
Southern Mexico Fri afternoon, and build seas to near 7 ft in 
offshore waters by Sat. Seas will subside there Sun and Mon.  


The monsoon trough will meander between 09N and 11N 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 
will spread across southern forecast waters, with seas building 
to around 8 ft S of 08N by early Sat, then gradually subside on 
Sun and Mon.

REMAINDER OF THE AREA... Low pressure centered near 13N116W is 
embedded in the monsoon trough with an estimated pressure of 
1011 mb. Model guidance shows the low emerging from the trough 
and drifting northward with a gradual increase in intensity 
through the weekend. The GFS is much more aggressive with this 
low than other global models, and is an outlier at this point. 
However, this low merits close observation over the next few 
days for signs of increased organization. 

A trough is analyzed from 14N137W to 07N140W. Scattered moderate 
convection is associated with this feature. Seas to 8 ft are 
evident near the trough axis in latest altimeter sea state data. 
The trough will drift westward, and move west of 140W Fri night.

Elsewhere, high pressure centered near well north of the area 
extends a ridge SE to near the Revillagigedo Islands. Gentle to 
moderate trades prevail west of 120W, and light to gentle winds 
dominate the remainder of the basin based on ASCAT data. A pulse 
of northerly swell will propagate into the northern waters with 
seas building to 6 to 9 ft north of 25N between 120W and 130W on 
Fri. Cross-equatorial southerly swell will build seas to 6 to 9 
ft south of 10N and west of 90W late Friday.