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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 111006

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Wed Dec 11 2019

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 0600 UTC surface analysis and satellite imagery through
0900 UTC.


A strong cold front has moved across the western Gulf of Mexico 
and through the Isthmus of Tehuantepec, with northerly winds to
25 kt beginning to blow across the Gulf of Tehuantepec tonight.
Gale force northerly gap winds will begin to blast across
Tehuantepec and spread southward by around sunrise, and expand
further southward through the day Wed. These gale force winds 
are expected to peak near 45 kt this evening, with seas building to
17 ft. Gale force winds will then persist through Wed night and
Thu, while diminishing very slowly Thu, before gradually tapering 
off to strong Thu night through Fri, and then below 20 kt by Sat


The monsoon trough extends from 09N75W to 06N90W to 10N110W to 
1011 mb low pressure near 08N116.5W to 06N120W. The ITCZ 
continues from 06N120W to 08N131W to beyond 08N140W. Scattered 
moderate to strong convection is noted from 04.5N to 09.5N
between 78W and 88W, from 06N to 12.5N between 100W and 120W, and
from 07N to 10.5N between 123W and 140W. 


1026 mb high pressure centered near 30.5N126W is maintaining 
moderate northerly flow off the coast of Baja California, 
depicted well in overnight scatterometer data. This 
scatterometer data also showed NNE winds around 20 kt spilling
out of strong northerly winds inside the Gulf of California,
across Baja California Sur, and across the near and offshore
waters near Todos Santos. Seas across the area were generally 
4-7 ft in NW swell, with highest seas south of Punta Eugenia. 
Little change in winds is expected through Wed, before 
diminishing slightly Wed night through Sat morning. However, new 
NW swell will move into the region from the far NE Pacific to 
raise sea heights to 5-8 ft by Thu morning and to 7-11 ft by Fri 
morning. A further increase in winds and seas is expected over 
the weekend and strong high pressure builds SE into the region. 

Inside the Gulf of California, northerly winds of 15-20 kt
prevail south of the Tiburon Basin, with areas of 20-25 kt winds
along the Baja coastline. Seas are 5-7 ft across this portion of
the Gulf. Very little change in these conditions is expected
through Thu evening before winds begin to slowly diminish through

Elsewhere off southern Mexico, outside of the Gulf of 
Tehuantepec, gentle to moderate flow NW to W wind flow will 
persist through Thu night and then freshen slightly on Fri, 
especially off Cabo Corrientes. Large seas will be generated by
this next gale event across Tehuantepec, and will spread south 
and southwestward, with seas 8 ft and higher reaching 10N by Thu 
morning, then moving south of 10N Fri morning.


Fresh NE to E winds will pulse to strong over the Gulf of 
Papagayo tonight, and then again Wed night and Thu night before
diminishing. The longest lived winds are expected Wed night 
through Thu with seas peaking around 8 ft. Elsewhere, gentle to 
moderate S to SW monsoon flow will persist across the offshore 
waters of Costa Rica, Panama, Colombia, and Ecuador through Sat 
night. Expect gentle to moderate NW winds to generally prevail
across the Gulf of Panama.


A 1026 mb high pressure center located near 30.5N126W is 
supporting fresh to strong tradewinds across the waters south of
24N and west of 115W. Recent altimeter data showed seas of up to
9 ft in the area of fresh trades, and this may increase slightly
through mid week as the trade winds persist. The high will move
slightly SW through Thu night and act to increase the pressure
gradient to its south, and expand the area of strong tradewinds 
to S of 26N and W of 120W.

A frontal boundary remains stalled NW of the discussion area 
near 31N144W. A much strong frontal system to the northwest of 
this front will also approach this same area and stall on Thu. 
Large NW swell will move out ahead of this next front and 
propagate into the regional waters beginning early Wed, and cause
seas in this area to build through Fri. Seas will eventually 
peak between 12 and 14 ft Thu night and Fri morning in the far 
northwest portions of the area. This swell will combine with wind
waves generated by the strong trade winds S of 20N Wed night 
through Thu night. A surface trough propagating W will further 
tighten the pressure gradient in this area and cause seas to 
build to between 10 and 14 ft from 10N to 20N W of 130W Fri night
and Sat.