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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 122315 CCA

Tropical Weather Discussion...Corrected
NWS National Hurricane Center Miami FL
2205 UTC Mon Nov 12 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
2145 UTC. 


Gulf of Tehuantepec Storm Warning: A strong cold front will move 
across the western Gulf of Mexico on Tue followed by a strong 
high pressure system. Winds are forecast to first reach minimal 
gale force across the Gulf of Tehuantepec by early in the
afternoon on Tue morning as strong high pressure over northeastern
Mexico surges southward along the east side of the Sierra Madre 
Oriental mountains and to southeastern Mexico. The resultant 
tight pressure gradient between the high pressure and the cold 
front will allow for the gale force winds to quickly increase to
storm force winds of 40 to 50 kt by late Tue afternoon or early 
evening. Seas downstream of the Gulf of Tehuantepec are expected 
to build up to the range of 13 to 22 ft by late Tue night and 
into Wed. The storm force winds are expected to continue through 
late Wed night, with gale force winds likely lasting into early 
Sat morning. A large swath of very high seas from this event 
will propagate to the south and southwest of the Gulf of 
Tehuantepec region, with the leading edge of the 8 ft seas 
forecast to reach near 108W by Fri.

Gale Warning along and west of the coast of northern Baja 
California: Strong high pressure building across the southwestern
United States and northern Mexico will bring strong to near gale
force northerly winds over the Gulf of California. These winds 
will funnel through mountain passages across Baja California 
Norte and bring minimal gale force northeast winds over regional
waters, from 28N to 30N E of 115W beginning late tonight, and 
continuing through early Tue evening. Fresh to strong, to at 
times strong to near gale force, northeast winds and building 
seas of 8 to 10 ft are also expected across the offshore 
forecast waters W of Baja California, mainly N of Cabo San 
Lazaro through late Tue night. 


The axis of a tropical wave extends from 07N118W to 16N117W, 
moving westward at 10 to 15 kt. A 1012 mb low is just west of 
the wave at 08N119W. Scattered moderate convection is within 
150 nm of the low in the SE quadrant and within 120 nm of the low
in the southwest quadrant. Scattered moderate convection is
within 120 nm east of the wave from 07N to 10N.


The monsoon trough axis extends from northern Colombia near
09N74W to Costa Rica and to 08N90W to 08N99W, where latest
scatterometer data indicates that it transitions to the ITCZ axis
to 07N100W to just east of the above described tropical wave. It
continues from just to the west of the 1012 mb low to 07N130W 
and to 08N140W. Scattered moderate convection is seen within 120 
nm north of the ITCZ axis between 121W and 124W and between 125W 
and 127W.



Please see the Special Features section for information on 
upcoming Gulf of Tehuantepec storm event and on a gale event 
off the west coast of Baja California Norte.

Gulf of California: The pressure gradient associated with strong 
high pressure north of the area is bringing strong to near gale 
force northwest winds over the northern and central Gulf. These 
winds will spread southward across the entire length of the Gulf 
of California and across the waters between Las Marias Islands 
and Los Cabos by late tonight. Seas are forecast to build to 8 
to 10 ft before starting to subside Tue morning as the high 
pressure center north of the area moves northward and weakens.


Fresh to strong northeast winds will pulse over the Gulf of 
Papagayo tonight, then diminish to fresh winds early Tue and 
diminish further to moderate to fresh winds thereafter. Winds 
will increase back to fresh to strong by Tue night as a tight 
pressure gradient develops over northern Central America behind 
a strong cold front that will move across the northwestern 
Caribbean Sea. Seas are forecast to build to 9 ft by Thu 
morning. This second gap wind event will last through the end of 
the weekend.

A strong Tehunatepec gap wind event W of the area is forecast 
to spread strong to near gale force winds and building seas of 
12 to 18 ft into the Guatemala and El Salvador offshore waters, 
mainly to the west of 92W, Tue night through Thu morning.

Otherwise, light to gentle winds are forecast north of the 
monsoon trough, with gentle to moderate SW winds S of the monsoon
trough through the next several days. Cross-equatorial long 
period SW swell will keep seas in the 6 to 7 ft range between 
Ecuador and the Galapagos Islands, and as far north as near the 
Azuero Peninsula through Wed.


High pressure of 1023 centered west of California near 33N128W 
extends a ridge southeastward across the northern forecast waters
to near the Revillagigedo Islands. The pressure gradient is 
forecast to tighten between the high pressure and lower pressure 
in the vicinity of the ITCZ from late tonight through Tue, resulting
in fresh to locally strong trades just north of the ITCZ. Seas 
of 8 to 9 ft will be associated with these winds covering roughly
the waters from 10N to 16N W of 119W by Tue, with the strong 
trades expected from about 10N to 15N between 122W and 126W. 
These conditions are forecast to last through Thu, while they 
shift westward and decrease in coverage. 

A stationary front is dissipating over the far northwest section 
of the area. Its remnants will lift back to the northwest and
north as a trough through Wed. Model guidance depicts that a 
cold front will approach the far northwest corner of the area 
on Fri. A set of northwest swell associated with the dissipating 
stationary front is forecast to cross 30N140W by late Tue night
into early Wed, with seas of 8 to 10 ft covering much of the 
waters north of 07N and west W of 130W by early Thu as the swell 
merges with swell created by the aforementioned area of fresh 
to strong trades.

Cross equatorial SW swell of 7 to 9 ft will propagate across the
waters S of 06N between 100W and 120W through early Wed.