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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 201605

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1530 UTC Tue Nov 20 2018

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 
1430 UTC.


Gulf of Tehuantepec Gale Warning: Strong to near gale force 
northerly winds will pulse across the gulf waters through this
coming afternoon. Stronger drainage flow this evening will 
result in minimal gale force conditions developing and then 
continuing through Wed morning. Associated seas are forecast to
build to up to 12 ft near 15N95.5W late tonight. The northerly 
winds are then forecast to be strong to near gale Wed afternoon 
to Fri morning. Please refer to the East Pacific High Seas 
Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more 


The monsoon trough axis extends from the coast of Costa Rica 
near 08N84W to a 1010 mb low pressure near 07N105W. The 
intertropical convergence zone axis extends from there to 
08N120W to another 1010 mb low pressure near 10N140W. Scattered 
moderate and isolated strong convection is within 180 nm south 
of the monsoon trough E of 87W.  Scattered moderate convection 
exists within 60 nm of the monsoon trough between 93W and 100W 
as well as 105W to 110W.  Scattered moderate and isolated strong 
convection appears within 180 nm of the ITCZ W of 118W.



See Special Features section for Gulf of Tehuantepec Gale 
Warning information.

Gulf of California: Fresh breeze or weaker winds through Sat 
night.  Enhanced pressure gradient from southwestern US to over 
the eastern Pacific should force NW strong breeze in the 
northern Gulf on Sunday.  Seas should remain below 8 ft.

A 1018 mb surface high is meandering near 27N118W with a weak 
ridge extending across the Mexican offshore waters W of near 
100W. Winds should remain at fresh breeze or weaker conditions 
through Fri night.  The same enhanced pressure gradient will 
briefly contribute to a NW strong breeze west of Baja California 
on Sat before diminishing again on Sun.

Long-period NW swell, in the form of 7 to 9 ft seas, will arrive 
at 32N120W late Thu, and reach the northern coast of the Baja 
Peninsula early Fri, with these swells propagating as far S as 
22N late Fri night through Sat before diminishing on Sun.


Gulf of Papagayo: Fresh to locally strong NE winds with seas 
building briefly to 8 ft are expected through early Fri. Winds 
will diminish in the Gulf late Fri through Sun.

The monsoon trough will meander between 08N and 10N for the next 
several days with NE moderate breeze or weaker north of the 
trough and SW moderate breeze or weaker south of the trough. 
Seas will remain below 8 ft.


A weak cold front extends from a 1013 mb low near 32N124W and 
extends in our area from 30N120W southwestward to 23N128W. A 
second cold front extends from a 1012 mb low near 30N130W 
southwestward to 26N135W.  Finally, a dissipating cold front 
extends from 30N138W to 28N140W in our northwestern corner. None 
of the three have any significant winds, seas, or convection 
associated with them.  

Behind this last front, long-period NW swell of at least 8 ft 
will be reaching 30N140W this afternoon.  These will progress 
southeastward across the basin, peaking around 12-14 ft on Wed 
near 30N135W.  The swell will gradually diminish in amplitude 
and drop below 8 ft on Fri.

A trough extends from 07N131W to 14N131W.  While winds are at 
moderate breeze or weaker, seas are up to 8 ft in mixed swell in 
a small area W of the trough.  These will diminish below 8 ft on 

Finally beginning Wed, the pressure gradient will tighten and 
result in a large area of strong breeze to near gale NE 
tradewinds generally between 12N and 22N W of 120W.  Peak seas 
will reach near 12 ft due to NE wind waves with the 
aforementioned NW swell.  These conditions will continue through 
Sat before diminishing on Sun.