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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 210900

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Tue Jan 21 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 
0900 UTC.


Gulf of Tehuantepec Storm Warning: Strong high pressure across 
southern Mexico is supporting winds reaching at least 48 kt, 
based on scatterometer data, through the Gulf of Tehuantepec. 
Maximum seas are estimated to be 22 ft downstream of the Gulf of 
Tehuantepec, and a plume of swell in excess of 8 ft extending 
several hundred nm downstream, expected to encompass much of the 
waters north of 03N and east of 105W today. Marine interests 
transiting across or in the vicinity of the Gulf of Tehuantepec 
through today should take necessary action to avoid hazardous 
marine conditions. Gales will continue into Wed morning, then 
quickly diminish Wed afternoon as the ridge weakens over Mexico.

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 Storm Warning.


A surface trough extends from near 06N77W to 07N87W to 05N100W. 
The ITCZ begins near 05N100W and continues to 07N118W to 06N140W.
Scattered moderate isolated strong convection is noted from 04N 
to 10N between 80W and 87W. 


Please see the Special Features above for more information on a
storm force gap wind event in the Gulf of Tehuantepec.

Weak high pressure centered near Guadalupe Island is maintaining 
light to gentle northerlies north of 17N, with moderate NW winds 
over the central and southern Gulf of California and near Cabo 
Corrientes. Outside of the Tehuantepec region, seas remain less 
than 8 ft throughout the forecast waters. 

Long period NW swell will reach the Baja California Norte waters 
today, building to 10-11 ft tonight. The swell will propagate SE 
across the region and reach the Revillagigedo Islands Wed night. 
Seas will gradually subside through Fri as the swell decays. 
Moderate northerly winds will develop west of Baja California 
Wed and Thu as high pressure builds NW of the region. Elsewhere, 
expect moderate to fresh NW winds over the central and southern 
Gulf of California Wed night through Fri as high pressure builds 
over the Great Basin region.


A large area of showers and thunderstorms continues to be active
off the coast of western Panama and Costa Rica. This activity is
north of a surface trough extending east to west along roughly 
05N. A Kelvin wave passing over this region is creating upper- 
level conditions that are conducive for enhanced convection, 
which will likely continue through tonight.

Strong trade winds in the SW Caribbean will continue to support 
strong NE to E winds downstream of the Papagayo region through 
Thu morning. Winds will be strongest during overnight and early 
morning hours. Seas will build to 10 ft each morning during the 
period of peak winds. Elsewhere, moderate to fresh northerly 
winds will persist in the Gulf of Panama region this week. 

Swell generated by a strong Tehuantepec wind event is spreading 
into the Guatemala and El Salvador offshore waters through Wed, 
with seas greater than 12 ft expected there through tonight.


A scatterometer pass from 0640 UTC indicated areas of fresh to 
strong winds north of an elongated low pressure area centered 
near 29N123W. The low will gradually weaken today and continue 
moving east-northeast, then dissipate early Wed near Guadalupe 
Island. The presence of this low center has disrupted the usual 
subtropical ridge over the area, resulting weaker trade winds in 
the deep tropics east of 130W, evidenced by scatterometer data 
and buoy observations.

A mid-level disturbance interacting with trade wind convergence 
along the ITCZ between 120W and 125W supports scattered showers. 
Farther west, a surface trough has developed along the ITCZ near 
135W in an area of deep layer moisture SE of a broad mid/upper 
level trough. This is a favorable area of further development. 
Fresh to strong NE winds could develop between the trough and 
high pressure building north of the area the next two days.

Long period NW swell crossing 30N140W will propagate SE across 
the forecast waters for the next several days. Seas greater than 
8 ft will dominate the region west of 120W by late tonight.

Looking ahead, a cold front accompanied by more long-period NW 
swell will pass southwest of 140W by Sat.