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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 231500

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1521 UTC Tue May 23 2017

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
1500 UTC.


The monsoon trough axis extends from 10N84W to 12.5N95W to
08.5N108W. The intertropical convergence zone axis extends from
08.5N108W to 08N120W to 07N140W. Scattered moderate and isolated
strong convection is N of 07N between 78W and 80W, N of 14N
between 92W and 96W, N of 16N between 99W and 101W, and from 04N
to 09N between 127W and 135W. Isolated moderate to strong
convection is within 120 nm S of the axis between 91W and 117W,
and within 120 nm N of the axis between 118W and 122W.



Weak high pressure remains centered well offshore of northern 
California, extending a weak ridge SE into the area through 
30N130W to near the Revillagigedo Islands. This is maintaining a
relatively weak pressure gradient across the offshore waters 
from Baja California to Acapulco, with moderate NW winds 
prevailing across the Baja peninsula waters, and light NW to W 
winds from Las Tres Marias to Acapulco. Seas are running 4 to 6 
ft in mixed NW and SW swell and will subside to 4 to 5 ft by 
tonight. The pressure gradient will tighten somewhat N of 20N 
Wednesday through Friday as the ridge builds modestly into the 
region, with winds and seas increasing slightly. 

In the Gulf of California, mainly light and variable winds are 
expected through Thursday, with seas of 2 ft or less, except 3 to
4 ft near the entrance. Low pressure will deepen just N of the
area over SW Arizona Wednesday night through the end of the week.
A trough will extend from that low across the northern Gulf to
Baja California Norte. Fresh to strong southerly winds will
develop SE of the trough Wednesday night, and then again on
Thursday night as winds become enhanced through the gaps in the 
higher terrain of Baja. Seas will increase significantly, 
reaching 6 to 7 ft each night during the nocturnal wind max.

S of 16N including the Gulf of Tehuantepec, broad and weak low 
pressure has persisted across the offshore waters SW of 
Tehuantepec the past few days, drifting to the W. Gentle to 
moderate SE to S winds occurring between Tehuantepec and 
offshore of Acapulco will gradually weaken and veer S to SW 
through Wednesday.


Moderate to fresh SE to E winds prevail between the Papagayo 
region and Tehuantepec, with seas of 5 to 7 ft in SW swell. 
Expect these conditions to continue today before gentle to 
moderate SW to W monsoonal winds spread N of 09N and into the 
coastal waters tonight into early Wednesday. Nocturnal offshore
winds will pulse to fresh levels near the Gulf of Papagayo
Saturday night. Moderate SW winds are expected S of 09N through
Thursday night, with seas subsiding slightly through Wednesday 
before a new pulse of SW swell arrives Thursday through late 
Friday. Otherwise, little change is anticipated through the 
upcoming weekend.


A weak ridge extends from a 1028 mb high near 40N139W SE to near
30N130W. The ridge will reposition itself from 32N142W to 
11N120W by Wednesday as a weak front or trough moves SE across 
the waters N of 30N by early Wednesday, accompanied by long 
period NW swell. This will build seas to 6 to 8 ft from 30N to 
32N between 120W and 135W. Elsewhere N of the convergence zone, 
the weak ridge will maintain moderate trade winds S of 18N, with 
seas of 5 to 7 ft expected. Little change is anticipated through 
the upcoming weekend.