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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 180211

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
210 UTC Tue Jun 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.


A tropical wave axis extends north of 04N along 88W, moving W at
10-15 kt. No convection is associated with the wave at this 

A trough extends from 06N to 12N along 101W, moving W at 10 to 15
kt. This feature emerged out of the mid latitudes over the 
Atlantic, and has propagated across Central America into the 
eastern Pacific over the past several days. Numerous moderate to 
scattered strong convection is observed near the trough, from 
06N to 12N between 100W and 102W. 

A tropical wave axis extends from 04N to 14N along 115W, moving 
W at 10 to 15 kt. Scattered moderate convection is evident from
07N to 13N between 110W and 118W. This wave is become less well
defined as it moves westward.

A tropical wave axis extends from 04N to 13N along 130W, moving 
W at 5 kt. No significant convection is observed. This feature
also looks much less defined and may be starting to dissipate.


The monsoon trough axis extends from 08N78W to 10N125W. The ITCZ
begins near 09N130W and continues to beyond 08N140W. Outside of
areas previously discussed near tropical waves, no significant
convection is observed at this time.



The pressure gradient between a high pressure ridge west of Baja 
California and a low pressure trough along the Baja California 
peninsula is maintaining moderate northwest to north winds 
across most of the adjacent offshore waters where seas remain in 
the 4-5 ft range. Winds and seas off Baja California will change 
little through next several days as the ridge remains over 
offshore waters. Surface low pressure is expected to cover a 
rather expansive area over the southwestern United States and 
along California through mid week as a sharpening mid to upper- 
level trough moves over those regions. This will allow gentle to
moderate winds through late in the week, with pulses of fresh to
strong gap winds into the northern Gulf of California Tue night
and again late Fri. Northwest swell will move into the waters off
Baja California later in the week. Light to gentle winds will 
persist farther south over Mexican offshore waters. 


An earlier scatterometer satellite pass showed fresh to strong
winds through the Gulf of Papagayo. This was due to a tight 
gradient between high pressure north of the area and lower 
pressure through the tropics. This pattern will support fresh to 
strong gap winds through the Gulf of Papagayo during overnight 
hours through mid week, and again Fri night and Sat. Elsewhere, 
fairly tranquil conditions will persist off Central America under
a weak pressure pattern. 

Long-period southwest swell propagating through the southern 
waters will build the waveheights to 9 ft between Ecuador and 
the Galapagos Islands through Tue. Wave model guidance suggests 
that new south to southwest swell will propagate through the 
southern waters west of 90W Tue night through Thu building 
waveheights there to a peak of 8 ft again before they begin to 
subside late on Thu. 


A ridge extends from 1030 mb high pressure centered near 37N140W
southeastward through the Revillagigedo Islands. An earlier
scatterometer pass indicated fresh trade winds south of the ridge
from 15N to 20N west of 135W. Various altimeter satellite passes
show seas generally 5 to 7 ft. A series of weak tropical waves 
will move across the deep tropical waters through Sat,
occasionally supporting locally higher winds, seas, and
thunderstorm activity. Northerly swell related to a gale center
off the California coast well north of the region will move in 
the waters north of 28N and west of 125W from late tonight
through the remainder of the forecast period. 

Farther south, long period southwest swell to 8 ft will move in 
to the waters south of 08N between 95W and 130W through Wed, 
before decaying below 8 ft by late Thu. Another round of 
reinforcing southwest swell will bring seas to 8 ft in the same 
area Fri and Sat.