Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 111556

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1407 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 1200 UTC surface analysis and satellite imagery through
1540 UTC.


A strong cold front has crossed the western Gulf of Mexico and 
the Isthmus of Tehuantepec. Gale force northerly gap winds have 
begun to blast southward across the Tehuantepec region. These 
gale force winds are expected to peak around 45 kt this evening,
with seas peaking around 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 morning. 


The monsoon trough extends from 09N75W to 06N91W to low pres 
1010 mb near 08N117W to 07N120W. The ITCZ continues from 07N120W 
to 08N132W to beyond 07N140W. Scattered moderate and isolated 
strong convection is noted from 05N to 08N between 77W and 89W, 
from 06N to 12N between 102W and 120W and from 07N to 09N W of 


1026 mb high pressure centered near 29.5N127W is maintaining 
moderate northerly flow off the coast of Baja California, 
depicted well in overnight scatterometer data. This scatterometer
data also showed NNW winds channeling southward along the eastern
shore of Baja. These winds were spilling out toward the SSW across
Baja California Sur as well as 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 winds diminish slightly
Wed night through Sat morning. However, a new round of NW swell 
will enter the region from the NW corner of the discussion area  
to raise sea heights to between 5 and 8 ft by Thu morning and to
between 7 and 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 to 20 kt 
prevail south of the Tiburon Basin, with areas of 20 to 25 kt 
winds funneling S along the Baja coastline. Seas are running 5 to
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 Fri through Sat. 

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 generated by the 
current Tehuantepec gale event will spread S and SW, with seas 8 
ft and higher reaching 10N by Thu morning, then propagating south
of 10N Fri morning.


Fresh NE to E winds will pulse to strong over the Gulf of 
Papagayo tonight with seas peaking near 8 ft, then moderate to 
fresh winds are expected for the remainder of the forecast 
period. 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, while moderate NW flow 
prevails 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. 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 cold front will approach 30N140W and stall Thu. Large NW swell
generated by gales behind the front will run ahead of front and 
begin spreading into the far NW waters by this afternoon, This 
will cause seas in this area to build through Fri. Seas will 
eventually peak between 12 and 14 ft Thu night and Fri morning in
this area. This swell will eventually combine with wind waves 
generated by the strong trade winds S of 20N tonight through Thu 
night. A surface trough heading W will further tighten the 
pressure gradient just N of the ITCZ and cause seas to build to 
between 10 and 14 ft from 10N to 20N W of 130W Fri night and Sat.


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Page last modified: Wednesday, 11-Dec-2019 15:57:09 UTC