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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 201005

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Jan 20 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 0600 UTC surface analysis and satellite imagery through 
0830 UTC.


Gulf of Tehuantepec Gale Warning: High pressure building across 
the eastern slopes of the Sierra Madre Mountains, behind a cold 
front moving across the Gulf of Mexico is generating a very 
tight pressure gradient over the area, and supporting gale force 
winds in the Gulf of Tehuantepec. Winds are forecast to increase 
to 45 kt Mon night. This stronger and much broader gale force 
gap wind event is expected to prevail through Tue night. Seas 
will peak to 21 ft Mon night during the period of the strongest 
winds. Swell generated from this event will produce a plume of 8 
ft or greater seas that will extend beyond 10N110W. Marine 
interests transiting across or in the vicinity of the Gulf of 
Tehuantepec today through Tue night should be aware of this wind 
event, and take necessary action to avoid hazardous marine 
conditions over the affected waters. 

Please see the latest High Seas Forecast issued by the National 
Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at
website for 
further details on this Gale Warning.


A surface trough extends from near 07N78W to 09N83W to 06N90W to 
05N97W. The ITCZ begins near 05N97W and continues along 06N120W 
to 07N136W. Scattered moderate isolated strong convection is 
from 03N to 09N E of 92W, from 04N to 09N between 110W and 115W, 
and from 06N to 16N W of 129W.


Please see above for more information on a gale force gap wind 
event in the Gulf of Tehuantepec, forecast to be near storm 
force later today.

Latest scatterometer data show light to gentle northerlies off 
the coast of Baja California being supported by a weak pressure 
gradient in the region. Seas across these waters range between 3 
to 7 ft as indicated by various ships, which coincide with the 
latest model guidance. These marine conditions will persist 
through Tue. By late Tue, a new set of long period NW swell will 
reach the waters N of Punta Eugenia, building seas to 10 ft. 
This swell event, with seas of 8 ft or greater will propagate 
across the entire offshore waters W of Baja California by late 
Wed, and reach the Revillagigedo Islands by Wed night. 
Afterwards, seas will gradually decay and subside Fri. 

High pressure will build over the Great Basin region by Wed 
night and will support moderate to locally fresh NW winds across 
the central and southern Gulf of California through Fri. 
Seas are forecast to be less than 8 ft during this period.


Strong trade winds across the southwest Caribbean will continue 
to support strong to near gale force NE to E winds across and 
downstream of the Papagayo region through Thu morning. Winds 
will be greatest during the overnight and early morning hours 
with the assistance of the nocturnal drainage flow. Seas will 
build to 10 ft during the period of peak winds.

The strong trades across the southwest Caribbean are also 
supporting moderate to fresh northerly winds in the Gulf of 
Panama. These winds will prevail through the end of the week 
with seas building to 6 ft.

Seas of 8 to 15 ft associated with the strong gale gap wind 
event in the region of Tehuantepec will spread over Guatemala 
and El Salvador offshore waters today through Wed night. 


Latest scatterometer satellite data indicate a large area of 
strong to near gale force winds within 180 nm of a low centered 
near 26N131W. Seas in the vicinity of the low are estimated to 
be near 12 ft. The low will weaken gradually while it moves east-
northeast and dissipate early on Wed as it reaches the waters 
west of Punta Eugenia in Baja California Norte.  

The presence of the low pressure over the subtropical region has 
disrupted the typical subtropical ridge over the area, thus 
resulting in mainly moderate trade winds over the deep tropics. 
This is evident in latest scatterometer data that coincide with 
recent altimeter data showing seas of 8 to 9 ft. 

A new set of long period NW swell will follow the low center. 
Seas are expected to build to 12 to 15 ft W of a line from 
30N132W by this afternoon. High pressure in the wake of the low 
center will bring an increase in the trade winds by Tue morning, 
particularly from 10N to 14N W of 130W. In this area, expect 
fresh to strong NE trade winds and seas building to 12 or 13 ft.