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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 052120

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2120 UTC Thu Dec 5 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 1800 UTC surface analysis and satellite imagery through
2100 UTC.


Gulf of Tehuantepec Gale Warning: Fresh to strong N to NE winds 
will pulse across the Gulf of Tehuantepec through Fri morning. A
cold front is expected to move across the Gulf of Mexico Fri
through Sat, and high pressure will build over eastern Mexico
behind the front. This will support gale force gap winds over the
Gulf of Tehuantepec beginning late Fri night and continuing
through Sat night. Seas will build to 12-13 ft downstream of the
Gulf on Sat night, then subside on Sun as wind speeds diminish to
fresh to strong speeds. Looking ahead, another gale force gap 
wind event could affect the Gulf of Tehuantepec during the middle
of next week, although the timing remains uncertain given the lack
of model agreement.

See latest NWS High Seas Forecast issued by National Hurricane
Center under AWIPS/WMO headers HSFEP2/FZPN03 KNHC or at website for more details.


The monsoon trough extends from 06N77W to 05N93W to 1011 mb low
pressure near 09N113W to 09N121W, then resumes from 10N131W to 
09N138W. The ITCZ extends from 09N138W to beyond 08N140W. Scattered
moderate isolated strong convection is noted within 120 nm south
of the monsoon trough between 101W and 106W. Scattered moderate 
convection is occurring from 03N to 06N between 81W and 85W, 
within 180 nm SE quadrant of low center, and from 08N to 10N west
of 135W.


Please see the Special Features section above for more details on
the Gulf of Tehuantepec Gale Warning.

A dissipating stationary front extends across the northern Gulf of
California to near 25N118W. Recent scatterometer data indicates 
light to gentle breezes prevail across most of the region under a
weak pressure pattern. Fresh to strong northerly gap winds are 
noted over and downstream of the Gulf of Tehuantepec.

Fresh NW to N winds will develop over the central and southern 
Gulf of California tonight and persist through Sat night. Large 
NW swell will enter the Baja California Norte waters on Sat, 
with offshore seas building to 8-12 ft by Sat night. This swell
will continue spreading SE across the region Sat night through
Sun night, then decay Mon into Mon night. The pressure gradient
over Baja California will strengthen early next week, resulting 
in fresh northerly winds offshore and over the Gulf of California.


Strong NE to E winds will pulse across and downstream of the 
Gulf of Papagayo through Tue, with seas peaking between 8-9 ft 
downstream of the Gulf each morning. SW winds will freshen off 
the coast of Colombia late tonight through Sat. Otherwise, gentle
to moderate S to SW monsoon flow will persist across the offshore
waters of Costa Rica, Panama, Colombia, and Ecuador during the 
next several days. 


A cold front extends across the NW waters from 30N136W to
27N140W. Recent scatterometer data shows fresh to strong NW winds
behind the front, with fresh SW flow noted ahead of the front. 
The front will cross the northern waters through Fri night, then
stall and weaken on Sat. Very large NW swell associated with 
this system will move into the NW portion tonight, then propagate
SE while gradually decaying through the weekend. Seas will build
to greater than 12 ft over the northern waters Fri through Sat, 
peaking in excess of 20 ft over the far NW portion on Fri.

Elsewhere, decaying NW swell lingers over the waters south of 
15N and west of 100W, with the latest altimeter data indicating 
wave heights have subsided to 7-8 ft across most of the region. 
These seas will continue subsiding through tonight.