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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 181546

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1605 UTC Sun Mar 18 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 
1545 UTC. 


Gale Warning: An initial cold front will move into the northwest 
portion of the discussion area today preceded by strong 
southerly flow with seas building to 9 ft. A deepening surface 
low pres well northwest of the area will drop southeastward to 
near 32N140W on Mon night behind this initial cold front, and 
drag a second cold front into the discussion area accompanied by 
a strong to near gale southwest-west-northwest wind shift. The 
pressure gradient will tighten around the southwest semicircle 
of the low increasing the westerly winds to 25 to 35 kt minimal 
gale force across the discussion waters from 29N to 30N west of 
139W at 1200 UTC on Tue, with the associated seas of 12 to 18 ft 
forecast from 26N to 32N between 136W and 140W. The low pres 
will lift north of the area on Tue night with associated winds 
diminishing to 20 kt or less south of 32N late Wed. The 
associated northwest swell, in the form of 7 to 10 ft seas, will 
propagate southeast across the discussion waters covering the 
area west of a line from the central Baja peninsula to 06N140W 
on Sat. Please refer to the Pacific high seas forecast for more 
details on this upcoming event under AWIPS/WMO headers 


A surface trough is analyzed from the Pacific coast of Colombia 
at 08N82W to 05N104W where scatterometer winds indicate an ITCZ 
develops, and continues W to beyond 05N140W. Scattered moderate 
isolated strong convection is noted within 90 nm either side of 
a line from 05N77W to 06N82W to 03N90W to 08N105W.  Similar 
convection is noted in small clusters within 30 nm of 09N122W 
and 05N128W. 



A north-northwest to south-southeast ridge is developing from 
30N121W to 17N110W to 13N94W. The ridge will shift slightly 
southwest on Mon and Tue. Fresh to locally strong northerly 
winds will set up south of 25N and east of the ridge briefly on 
Mon with the pressure gradient then relaxing some on Tue. Light 
to gentle northerly winds and 2 to 4 ft seas are then expected 
west of the Baja Peninsula through Thu night with large 
northwest swells arriving at 30N120W on Fri.  

Gulf of California: A weakening cold front will pass through the 
far northern gulf waters by this evening. Fresh to locally 
strong NW flow north of the front will diminish with moderate to 
fresh northwest flow forecast across the entire gulf waters 
tonight through Mon, with narrow swaths of strong northwest 
winds possible across the far southern gulf waters briefly late 
Mon.  Seas may build to 6 ft in the longer fetch waters.

Fresh to locally strong northwest to north flow expected across 
the open Pacific waters from 18N to 23N east of 110W through 
late Mon night with seas building to 8 ft.

Gulf of Tehuantepec: Strong north flow will surge through the 
gulf waters on Tue evening, increasing to minimal gale force 
around sunrise on Wed. Gale conditions are then expected to 
continue through Thu morning, with seas building to 14 ft 
downstream near 14.5N95.5W on Wed night. 


Gulf of Papagayo: Fresh to locally strong NE nocturnal winds 
expected tonight and again briefly on Tue night with seas 
building to 7 ft downstream.  A stronger drainage event is 
forecast to begin on Wed night and persist into the upcoming 

Gulf of Panama: Fresh northerly winds are expected tonight. 
Fresh to strong north nocturnal winds are expected to resume on 
Wed night.

Elsewhere, gentle to moderate offshore flow will prevail N of 
07N while light to gentle SW winds are forecast S of 07N. 


Refer to the Special Features Section above.