000
AXPZ20 KNHC 220228
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2259 UTC Wed Jun 21 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 0000 UTC surface analysis and satellite imagery through
0215 UTC.

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

The monsoon trough axis extends along the coast of Central
America to a 1007 mb low pressure near 12N94W to 09N110W to 
09N120W to 07N130W. The ITCZ continues from 07N130W to beyond 
08N140W. Scattered moderate convection is within 75 nm north of 
the monsoon trough between 104W and 112W, and within 90 nm s of
the monsoon trough between 117W and 119W. 

An area of showers, with embedded tstms, is noted from 04N to 
10N between 80W and 90W in a southwesterly wind flow. This 
convective activity is affecting parts of Panama. A diffluent 
pattern aloft in helping to induce this convective activity.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Moderate to locally fresh northerly flow is noted off Baja 
California Norte between a trough over the peninsula and a ridge
that covers the remainder of the northern forecast waters. This 
pattern is also supporting moderate to locally fresh southerly 
winds over the Gulf of California south of 30N. Expect moderate 
to fresh southerly winds across the northern Gulf of California 
tonight and Thursday, and then again on Sunday. Northerly swell 
of 8 to 9 ft will continue to propagate across the western part 
of forecast zones PMZ011 and PMZ013 through Friday. A developing
trough just west of the southern Baja California Peninsula is 
producing mainly light to gentle winds across the waters from 15N
to 25N between 110W and 120W. This trough will move westward on 
Thursday, enhancing southerly flow near Los Cabos and across 
much of the Gulf of California. This trough could be the surface
reflection of an upper-level low currently spinning near 22N117W.

Farther south, a broad area of low pressure has formed a few 
hundred miles south of the Gulf of Tehuantepec. Some development 
of this system is possible by this weekend while it moves 
westward to west-northwestward parallel to the coast of Mexico.
An earlier ASCAT pass showed the cyclonic circulation associated
with the low, with a trough extending northward toward the Gulf
of Tehuentepec. The same scatterometer pass provided observations
of gentle to moderate winds around the low center. This low is
forecast to support moderate to locally fresh east to southeast 
winds off the coasts of Chiapas and Oaxaca Friday and Saturday. 

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

Gentle to moderate southwest to west winds are expected across 
most of the forecast area during the forecast period, with the 
exception of mainly southerly winds between Ecuador and the 
Galapagos Islands. Long period SW swell will continue to impact 
the forecast waters with seas of 6-7 ft. Seas will gradually 
subside to 5-6 ft by Thursday night, and to 4-5 ft on Friday.

REMAINDER OF THE AREA...
 
A ridge dominates most of the waters north of the ITCZ/Monsoon
Trough and west of 120W. Scatterometer and altimeter data showed
an area of fresh to strong NE to E winds across the NW corner of
the forecast region, with seas to 9 ft. These marine conditions
are likely associated with a relatively tight pressure gradient
across that area. The ridge will shift west as the above mentioned
trough also drifts west. A broad and weak low pressure is forecast
to develop along the trough axis near 18N118W by tonight.

Northerly swell will continue to propagate across the waters
north of 20N, building seas up to 11 ft through Friday night.
Seas will gradually subside, from east to west, across the 
north waters on Saturday. 

$$
GR