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Eastern North Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 170226
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Thu Aug 17 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
0200 UTC.

..TROPICAL WAVES...

A tropical wave is N of 10N along 87W. Scattered moderate 
convection is observed from 12N to 14N between 86W and 88W.  
This wave is helping to induce some shower and thunderstorm 
activity over parts of Honduras, Nicaragua and El Salvador. 

A tropical wave is N of 10N along 103W and has moved W at 15 kt 
over the past 48 hours. Scattered showers with isolated tstms are
noted on either side of the wave axis between 100W and 106W.
An earlier ASCAT pass showed the wind shift associated with this
wave, as well as moderate to fresh winds on either side of the 
wave axis, with seas to 8 ft on the east side. The wave coincides
with a well defined 700 mb trough, and a high amplitud northward
bulge of moisture is noted on the TPW product.

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

The monsoon trough extends from 10N85W to 08N91W to 12N103W to a
1009 mb low pressure near 11N108W to 13N124W to 11N135W to 13N140W.
Scattered moderate isolated strong convection is from 09N to 12N
between 111W and 119W, near 11N123W, and within 120 nm S of the 
monsoon trough between 130W and 135W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A ridge will dominate the forecast waters west of Baja California
producing mainly gentle to moderate northerly winds and seas in
the 4-6 ft range the remainder of the week into the upcoming 
weekend. A surface trough will meander across the Baja California
Peninsula and Gulf of California through Sat night, with a 
surface low developing intermittently over the northern Gulf of 
California.

Gulf of California...gentle southerly flow will persist across 
the Gulf of California through the upcoming weekend, with the 
exception of moderate to locally fresh winds that will surround 
the low pressure center over the waters N of 30N.

Gulf of Tehuantepec: fresh to strong northerly winds are expected,
with the assistance of the drainage flow, during the overnight 
and early morning hours Thursday through Monday. Seas are 
forecast to build to 6-8 ft with these winds. On Monday, winds
are forecast by the computer model to increase to 30 kt with 
seas building to 9-10 ft as a tropical low approaches from the 
east.

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

Gulf of Papagayo: fresh to strong offshore winds are expected 
during the overnight and early morning hours through Friday 
morning, with moderate to fresh winds thereafter.

Gentle NE to E winds are expected N of the monsoon trough, while
moderate southerly winds are expected S of the monsoon trough 
axis through the upcoming weekend with 3 to 6 ft seas throughout.

REMAINDER OF THE AREA...

A surface low of 1009 mb is analyzed within the monsoon trough 
at 11N108W or about about 600 miles south-southwest of Manzanillo,
Mexico. Numerous moderate convection is noted within about 45 nm
of the low center. Scattered moderate convection is seen elsewhere
from 09N to 17N between 100W and 106W. This convective activity 
remains disorganized. Environmental conditions are expected to 
be conducive for some development during the next several days 
while the system moves west-northwestward at 10 to 15 kt. An 
earlier scatterometer pass provided observations of fresh to 
strong SE to S winds on the east side of the low center, likely 
associated with an area of strong convection previously observed 
in association with this low. Marine guidance indicates fresh to 
strong winds in the NE quadrant of the low center first, then in 
the N semicircle thereafter. The low is forecast to reach near 
13N113W late Thu and near 14N118W late Fri.

Another surface low pressure is near 17N118W. Convection is
limited in association with this low. Satellite imagery shows 
only scattered moderate convection within 45 nm W semicircle of 
low center. The most recent ASCAT pass provided observations on 
fresh to strong winds within 120 nm NE quadrant of low with seas
to 8 ft. These marine conditions will persist during the next 24
hours when the low is forecast to reach a position near 16N123W.

The remnants of former tropical cyclone Jova continue to spin 
near 18.5N132W with a central pressure of 1010 mb. A well defined 
swirl of low clouds is still noted on Experimental GOES16 related
to this low. The pressure gradient between the low and a ridge 
to the north is supporting moderate to fresh winds and seas of 7 
to 8 ft ft within about 180 nm NW quadrant of low. This feature 
is forecast to move toward the SW and weaken to an open trough by
Fri.

The subtropical ridge dominates the north waters producing mainly
gentle to moderate NE-E winds. 

An area of seas to 8 ft in southerly swell covers the waters from 
07N to 11N between 105W and 110W, and from 06N to 08N between 110W
and 114W. These seas will propagate westward, merging with seas
associated with the low pres located near 11N108W. 

$$
GR

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Page last modified: Thursday, 17-Aug-2017 02:27:06 UTC