Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 190359

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Mar 19 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 0000 UTC surface analysis and satellite imagery through
0345 UTC. 


Gale Warning: A weakening cold front over the far northwest 
portion of the area along a position from 32N137W to 28N140W is
preceded by strong southerly flow north of 25N and within 420 nm
to its east, along with seas of 8 to 10 ft. A deepening surface 
low pres system currently 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 near 0900 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 on Wed
evening. The associated NW swell, in the form of 7 to 10 ft 
seas, will propagate southeastward through the 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 axis is analyzed a low pres over NW Colombia
westward to across northern Panama and to just offshore the
border between Costa Rica and Panama continuing to 06N90W to
05N99W, where latest scatterometer winds indicate the ITCZ axis
begins and continues westward to 06N120W to 07N130W to beyond 
06N140W. Scattered moderate isolated strong convection is noted 
within 30 nm N of the axis between 117W and 120W. Scattered
moderate convection is within 60 nm S of the axis between 86W and



A north-northwest to south-southeast ridge extending from 
30N121W to 17N110W to 13N94W will shift slightly to the  
southwest through Tue. Fresh to locally strong northerly winds 
will set up south of 25N and east of the ridge briefly on Mon and
Mon night 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 Wed. Broken to 
scattered mid and high level clouds are advecting eastward
towards northern and central Baja California north of 26N.

Gulf of California: Moderate to fresh northwest flow is forecast 
across the entire gulf waters today, with narrow swaths of 
strong northwest winds expected across the far southern gulf 
waters late Mon. Seas may build to 6 ft in the longer fetch 

Fresh to locally strong northwest to north flow expected across 
the open Pacific waters from 18N to 23N east of 110W through 
late tonight 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
Wed evening. Gale conditions are then expected to continue 
through Thu morning, with seas building to a maximum of around
13 ft downstream from the gulf near 14.5N95.5W on Wed night. 


Gulf of Papagayo: Fresh to locally strong NE nocturnal winds
will diminish to moderate winds this afternoon, then increase to
strong winds 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 weekend. 

Gulf of Panama: Fresh northerly winds will diminish to moderate 
winds this afternoon. 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. 


Please see see Special Features Section above for details on 
upcoming gale force winds to impact the far NW portion of the 
area in the short-term.

The mid/upper level low pres system located to the northwest of 
the area and its related trough that will induce and drive the 
aforementioned surface low and cold front is preceded by mid to 
upper level moisture in the form of overcast cloudiness. Areas of
rain along with scattered showers and isolated thunderstorms 
under upper level divergence that is present to the the east and 
southeast of the mid/upper low have moved over the area north of 
about 27N and west of 120W. This clouds and precipitation will 
continue advancing eastward towards the general area of southern 
California and also northern and central Baja California through
Wed per model moisture guidance fields.


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Page last modified: Monday, 19-Mar-2018 03:59:27 UTC