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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 181542
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1308 UTC Sat Jan 18 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.

...SPECIAL FEATURES...

Gulf of Tehuantepec Gale Warning: High pressure over the Gulf of 
Mexico will maintain strong to minimal gale force N winds across 
the Tehuantepec region through Sun. Seas in excess of 8 ft reach 
several hundred miles downstream of the Gulf, mixing with longer 
period NW swell. Looking ahead, a cold front will move across 
the Gulf of Mexico Sun and Mon, and induce a stronger and much 
broader gale wind event across the Tehuantepec region Sun night 
through Tue night, then diminishing on Wed. Winds will peak 
around 40 kt, with seas building to 16 or 17 ft. Winds will be 
greatest during the overnight and early morning hours with the 
assistance of the nocturnal drainage flow.

Papagayo region Gale Warning: A broad persistent ridge across 
the Caribbean and Central America is supporting strong to near 
gale force NE to E winds across and downstream of the Papagayo 
region, extending downstream more than 200 nm. Winds will pulse 
to minimal gale force this morning, then frequent gusts to gale
force are expected, particularly during the overnight and early
morning hours. Seas will peak between 10 and 12 ft during this 
period of peak winds. Fresh to strong NE to E winds will prevail
across the region most of the forecast period.

Please see the latest High Seas Forecast issued by the National 
Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at
website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for 
further details on these two Gale Warnings.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

A surface trough extends from near 05N77W to 04N80W to 06N87W to 
05N97W. The ITCZ continues from 05N97W to 06N120W to beyond 
08N140W. Scattered moderate convection is from 06N to 09N W of
129W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see above for more on the latest gale force gap wind 
event in the Gulf of Tehuantepec.

A surface ridge dominates the offshore forecast waters W of Baja
California and extends to near the Revillagigedo Islands. Latest
ship observations and scatterometer data show moderate to fresh 
NW winds off the coast of Baja California and fresh to locally
strong winds across the Gulf of California, mainly S of 29N.

Strong high pressure building over the Great Basin of United 
States will set up a tight pressure gradient in the Gulf of 
California, and support fresh to strong winds over the central 
and southern Gulf of California through early Sun. These winds 
will spread out across the waters between Cabo Corrientes and Los
Cabos today and tonight. Looking ahead, a cold front will approach
Baja California Norte and Guadalupe Island Tue and Tue night, 
accompanied by NW swell of 8-10 ft, before stalling and dissipating
Wed.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR... 

Please see above for more on the latest gale force gap wind 
event in the Papagayo region.

The pressure gradient responsible for the gap wind events in 
southern Mexico and Central America is also supporting fresh to 
strong NE to E winds across the Nicaragua Lake in Nicaragua and 
offshore of the Gulf of Fonseca, as well as fresh to locally
strong northerly winds in the Gulf of Panama, mainly at night. 
Winds across the Gulf of Panama and downstream S of the Azuero 
Peninsula to near 04N will persist through Sun morning, with 
downstream seas building to 6-7 ft.

REMAINDER OF THE AREA...

A ridge extends across the northern forecast waters between Baja
California and 140W. Latest scatterometer data indicate fresh to
strong trades across the southern periphery of the ridge, over 
the waters from 08N to 15N W of 130W and from 08N to 20N between 
120W and 130W. This area of winds will gradually shrink in size 
Sun and Mon as a low pressure system, mentioned below, moves NE 
across the waters N of 20N. 

Just W of the region, a 1012 mb low pressure is analyzed near 
26N142W with a trailing cold front to near 16N145W. The low 
pressure and associated cold front are forecast to move across 
the NW forecast region later today through at least Mon. Fresh to
strong winds are expected ahead and behind the front through 
Mon. A new set of long period NW swell will follow the low/front 
with building seas of 12 to 15 ft W of a line from 30N135W to 
25N140W by Mon morning. Looking ahead, the pressure gradient 
between high pressure building in the wake of the exiting low 
pressure system and lower pressures in the vicinity of the ITCZ 
is forecast to support fresh to strong NE winds between the ITCZ 
to around 20N west of 130W Tue and Wed. 

$$
GR