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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 312155

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sat Oct 31 2020

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
2130 UTC. 


Gulf of Tehuantepec Gale Warning: High pressure continues to
build across the Gulf of Mexico behind a frontal boundary that 
currently extends over the western Caribbean. Latest
scatterometer data depicts 30 kt winds in the area close by the 
Tehuantepec region. Rough seas have built due to these winds, 
near 13 ft. Winds will diminish slightly to minimal gale force 
through tonight. A reinforcing cold front is expected to move 
into the southwest Gulf on Sun allowing for gale force winds to 
increase to near 40 kt through early next week. Northerly swell 
will mix with longer period southerly swell to support seas in 
excess of 8 ft well downstream of the Gulf of Tehuantepec, with 
peak seas building back to near 20 ft early next week. Please 
refer to the latest High Seas Forecast issued by the National 
Hurricane Center at: for further 

Potential Heavy Rainfall event: Heavy rainfall continues to be 
possible across portions of Central America late this weekend 
into early next week, particularly western Panama and Costa Rica 
to begin with, then spreading northwestward early next week. When 
heavy rainfall occurs, flash flooding and mudslides may be 
possible. Refer to statements provided by your national 
meteorological service for more details.


A tropical wave axis is along 93W from 02N-16N, moving W at 
around 10 kt. No significant convection is related to this wave 
at this time.


The monsoon trough extends from 08N86W to 1010 MB low near 
12N113W to 10N140W. Scattered moderate convection is noted 
within 120 nm on either sides of the axis between 100W-140W.


Please refer to the Special Features section above for details 
on the Gulf of Tehuantepec Gale Warning.

High pressure west of Baja California is supporting gentle to
moderate northerly breezes across the Mexican offshore waters 
off Baja California and the Gulf of California. Seas of 2-4 ft 
prevail in both the open waters and in the Gulf of California. 
Seas will build to 4 to 6 ft in the waters of Baja California by 
early next week. Elsewhere, little change is expected through the
next several days.

Gentle winds persist south of Cabo Corrientes outside of the
Gulf of Tehuantepec plume, with seas of 4 to 6 ft in mostly 
southerly swell. Little change is expected.


Moderate south to southwest winds will prevail south of the 
monsoon trough through Sun, with isolated areas of fresh winds
ahead and behind of a tropical wave. Seas are expected to 
increase offshore of Guatemala and El Salvador through tonight due
to gale force winds in the Gulf of Tehuantepec pushing northerly
waves into the area. Larger seas are expected early next week 
across this same area due to greater coverage and strength of the
Tehuantepec gap winds NW of the area. Elsewhere seas are mainly 
5 to 7 ft in mainly long period southerly swell. Seas will build 
slightly to the south and east of the Galapagos Islands into 
early next week due to reinforcing southerly swell.

Moderate offshore gap winds are expected across the Papagayo 
region through Sun before turning onshore and pulsing to fresh 
through the week. 


High pressure dominates the waters north of 15N. The gradient 
between the high pressure and lower pressures associated with the
monsoon trough will continue to support moderate to locally 
fresh NE trade winds from the monsoon trough to 20N and west of 
115W, for the next several days. Seas are 5 to 7 ft across this 
region, in a mix of swell and easterly wind waves. Little change 
is expected through the weekend.

A complex low pressure system north of the Hawaiian Islands is 
forecast to move NE through the weekend. A trailing front may 
slip southeast of 30N140W by early next week with winds remaining
20 kt or less. Associated seas will build to 8-9 ft behind this 
boundary on Mon afternoon/evening, impacting the waters north of
26N and west of 137W.

South of the monsoon trough, moderate to fresh S to SW winds 
prevail between 100W and 140W, where seas are 5 to 8 ft. Minor 
fluctuations in winds and seas are expected across this area 
through the weekend. 

Looking ahead, computer models suggest that a broad area of low
pressure could become organized by late Monday and move WNW 
through the end of the week. There is broad disagreement among 
the main global models, and confidence remains low on the exact 
locations and intensity of this low pressure at this time.