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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 290232

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
020 UTC Thu Jun 29 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.


A tropical wave is over northern Central America along 86W/87W N
of 09N. The wave, combined with the monsoon trough, is generating
some shower and thunderstorm activity over parts of Central 

A second tropical wave is along 97W north of 09N moving west at 
10 to 15 kt, with minimal convection associated with the wave.


The monsoon trough extends across Panama and Costa Rica to 
11N90W to 10N100W to 12N110W to 11N118W. The ITCZ continues from
11N118W to 09N130W to 07N140W. Scattered moderate isolated strong 
convection is from 06N to 11N between 89W and 93W, and from 06N 
to 10N between 120W and 134W.



Visible satellite imagery continues to show the remnant low of 
Dora spinning near 20.5N115W, with a central pressure of 1010 
mb. A well defined swirl of low clouds is associated with this 
system. Winds of 20-25 kt are still noted within 60 nm of the 
center, with seas to 8 ft. It will continue to weaken tonight, 
then dissipate on Thursday.

Gentle to moderate winds are noted over the remaining waters 
west of Baja California, with light to gentle winds prevailing 
elsewhere, with the exception of moderate to locally fresh 
southerly winds across the northern Gulf of California. Latest 
scatterometer data confirmed the presence of these winds, 
forecast to persist through Thursday night. Similar wind speeds
are expected again across the northern Gulf of California 
Saturday night through Monday as the pressure gradient tightens
across the area between a ridge to the west and a trough over
inland Mexico.

Seas are 3-4 ft in the northern Gulf of California, and also near
the entrance of the Gulf, with seas of 1-3 ft elsewhere. Seas of
4-6 ft are observed across the offshore forecast waters west of 
Baja California, outside the influence of the remnant low of 
Dora. Seas of 4-5 ft are expected west of Baja California and 
between Los Cabos and Manzanillo on Thursday. On this day, seas 
will increase to 6-7 ft in long period SW swell across forecast 
zones PMZ025 (States of Michoacan and Guerrero to 250 nm 
offshore) and PMZ027 (States of Oaxaca and Chiapas, including the
Gulf of Tehuantepec). 


Gentle to moderate SW to W winds are expected across most of the
region, except for southerly winds between Ecuador and the 
Galapagos Islands. Cross equatorial SW swell continues to
propagate across the region with seas of 8 to 9 ft. Seas of 6-7
ft will dominate most of the forecast waters W of 80W late on 

Expect fresh to locally strong winds and building seas to 8 ft 
across the Gulf of Papagayo and downwind to 89W Thursday night 
through late Friday morning.


A ridge dominates the waters N of 15N W of 120W, producing 
mainly light to gentle winds and seas generally under 6 ft. 
As the remnant low of Dora dissipates late Thursday, the ridge
will build farther east, reaching again the Revillagigedo
Islands. Cross equatorial long period SW swell will continue to 
propagate into the southern waters, building seas to 8-10 ft  
mainly east of 125W south of 08N into Thursday. Seas of 6-7 ft
will reach much of the coast of Central America and SW Mexico by
late Thursday.

On Saturday, northerly swell will reach the north waters buiding
seas to 8 ft, mainly across the area north of 27N between 120W 
and 127W.

Looking ahead, a broad area of low pressure is expected to form 
this weekend a few hundred miles south of the southern coast of 
Mexico. However, environmental conditions have become less 
conducive for much additional development while the system moves 
west-northwestward early next week.