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Eastern North Pacific Tropical Weather Discussion



156 
AXPZ20 KNHC 180325
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Feb 18 2019

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 
0200 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...Updated 

A surface trough extends from northwestern Colombia to 04.5N83W 
TO 05N94W TO 04N100W. The ITCZ begins from 04N100W TO 00N120W TO 
00N130W. Widely scattered clusters of moderate convection are 
noted within 150 nm N of the ITCZ between 104W and 111W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

A strong and persistent ridge extends southeastward across the 
discussion area, from the NE Pacific through 32N136W to near 
10N107W. The tight pressure gradient between the ridge and lower 
surface pressure over the southwestern United States and Mexico 
has been supporting strong northwest winds across the offshore 
waters for over 24 hours, and have finally begun to diminish to 
around 15-25 kt this evening as the ridge is realigning in 
advance of an approaching cold front. Seas associated with these 
winds are in 8-13 ft range in NNW swell, while these marine 
conditions remain rough and dangerous. 

A new cold front is sinking SSE across the offshore waters of 
Southern California this evening and will sweep across far north 
portions of Baja California tonight through Mon night and act to 
reinforce this NW wind flow. However, this will also weaken 
slightly the pressure gradient and lead to winds continuing to 
slowly diminish to 15-20 kt across most of the waters by Mon 
night, then become moderate to fresh Tue and Wed. Seas will also 
gradually subside tonight through Mon as the current large NW 
swell moves SE of the area. However, reinforcing NNW swell from 
this next approaching cold front will maintain seas at 7-11 ft 
Tue through Wed.

Gulf of California: Low pressure and its associated cold front 
will move across the northern part of the Gulf of California 
tonight, bringing fresh to strong SW to W winds to the northern 
part of the Gulf of California ahead of the front tonight, and 
then fresh to strong NW winds behind the front midday Mon 
through Mon night. Fresh northerly wind flow is then expected 
throughout most of the Gulf on Tue, diminishing to moderate to 
locally fresh Tue night through Wed.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR...

Gentle northeast winds across the Gulf of Papagayo will increase
again to the mainly moderate speeds on Mon, and to stronger
speeds of fresh to moderate Mon night into Tue. Light and 
variable winds are expected elsewhere through Tue, except for 
the Gulf of Panama where moderate northerly winds are expected.

REMAINDER OF THE AREA... 

A strong 1040 mb high pressure center, well to the north- 
northeast of the Hawaiian Islands near 42N145W, will remain in 
this general location through Wed. The associated ridge axis 
extends southeastward through 32N136W to the tropics near 
10N107W, which has forced the ITCZ southward to along the 
equator. The pressure difference between this ridge and broad 
low pressure lingering across the Hawaiian Islands area is 
resulting in a tight pressure gradient across most of the area N 
of about 08N and W of 110W. Northeast to east winds of 20 to 25 
kt are generally west of a line from 30N140W TO 10N128W TO 
09N128W TO 08.5N140W, where seas are in the range of 10 to 15 
ft. This current overall synoptic pattern will change very 
little through the next couple of days as low pressure north of 
the Hawaiian Islands along 25N pulls northward and away from the 
islands. The area of strong northeast to east winds will 
persist, but over a gradually smaller section of the western 
side of the discussion area. The seas there will slowly subside 
to around the 10 to 12 ft through the next 48 hours as the large 
swell gradually propagates SE of the area.

$$
Stripling