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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 142115

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2115 UTC Tue Aug 14 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 1800 UTC surface analysis and satellite imagery through
2100 UTC. 


1009 mb low pressure is centered near 11N119W along a tropical
wave extending form 05N to 17N along 119W/120W, moving west at 
10 to 15 kt. The surface low is centered south of a mid/upper 
level ridge, resulting in deep layer easterly shear. The surface 
center is partially exposed, with scattered moderate to isolated 
strong convection currently extending within 180 nm in the 
northwest quadrant of the low. A recent ScatSat pass showed 20 to
25 kt winds within 90 nm in the northern quadrant of the low. Showers
and thunderstorms continue to become better organized, and a 
tropical depression is likely to form tonight or Wed while the 
disturbance moves westward.


The monsoon trough extends from 09N79W to developing low 
pressure centered near 11N119W. Scattered moderate strong 
convection is noted within 90 nm south of the monsoon trough 
between 105W and 109W.



Weak ridging persists across the waters east of Baja California,
supporting gentle to moderate NW flow and 3 to 5 ft seas in the 
adjacent offshore waters. 

Gentle to moderate SE breezes continue across the Gulf of
California, although brief pulses of moderate to fresh W to SW
winds are possible over the far northern Gulf tonight into Wed,
and again nightly through the week.

Farther south, long period SW swell will move into the offshore
waters between Puerto Angel and Baja California Sur through Wed,
with seas peaking at 7 to 10 ft Wed evening into Thu morning, 
and highest seas across the waters between Guatemala and Cabo 
Corrientes. This will produce very large and dangerous surf 
conditions along the coastlines and outer reefs with localized 
breaking waves 15-20 ft Wed through Thu morning. 

Looking ahead, fresh to strong gap winds are expected by Thu 
night in the Gulf of Tehuantepec.


Gulf of Papagayo: Fresh gaps winds are expected during the
overnight hours through mid week followed by fresh nocturnal 
easterly flow through Fri morning. 

Gentle to occasionally moderate E winds are forecast elsewhere N
of the monsoon trough which is meandering between 09N and 11N. 
Moderate to locally fresh southerly winds are forecast S of the 
monsoon trough through early next week. Long period S to SW swell
has spread into the regional waters overnight and has raised 
offshore seas to 6 to 8 ft on either side of the Galapagos 
Islands. A stronger and larger pulse of SW swell will move into 
the regional waters tonight. This next pulse of cross equatorial
swell will raise seas to 7-9 ft Wed through early Thu before 
slowly subsiding through Fri, and produce large and dangerous 
surf conditions along the coasts and outer reefs.


Weak 1010 mb low pressure is centered near 17N132W, moving W-NW
at 10 to 15 kt. There is no significant convection near the low,
and it is weakening rapidly. Fresh winds are still likely on the
northern periphery of the low center, and seas may still be
reaching 8 ft. Building high pressure north of the area will
allow the area of fresh easterly winds and 8 ft seas to expand,
even as the low pressure opens into a trough over the next couple
of days, reaching 140W by Wed night. 

Farther to the northwest, the remnant low of Kristy is centered
near 24N139W, with an estimated pressure of 1014 mb. The low is
weakening, and a recent scatterometer pass showed generally
moderate winds near the low pressure as it drifts west of the

Long-period cross-equatorial southerly swell, in the form
of 7 to 10 ft seas, will propagate N across the tropical waters 
S of 20N E of 120W tonight through Thu, and then subside to less 
than 8 ft on Thu night.