Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 162139

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Wed Aug 16 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 1800 UTC surface analysis and satellite imagery through
2100 UTC.


A tropical wave is N of 10N along 81W. Scattered moderate 
convection is observed within 90 nm on either side of the wave 
axis from 10N to 15N. This convective activity is now affecting 
parts of eastern Honduras and Nicaragua. This wave has been 
progressing W at about 20 kts across the western Caribbean, but 
is expected to slow its forward speed over the the next few 

A tropical wave is N of 10N along 102W and has moved W at 15 kt 
over the past 48 hours. Scattered moderate and isolated strong 
convection is noted from 10N to 16N between 100W and 102W. 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. The wave coincides with a well defined 700 mb trough, 
and a high amplitud northward bulge of moisture is noted on the 
TPW product.


The monsoon trough extends from 10N85W to 08N90W to 12N101W to
a 1010 mb low pressure near 11N107W to 13N123W to 11N134W to
13N140W. Scattered moderate convection is N of 06N between 80W
and 84W. Scattered moderate isolated strong convection is from
07N to 10N between 89W and 94W, from 10N to 12N between 112W and
124W, and within 120 nm S of the monsoon trough W of 130W.



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 work week. 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 to locally moderate 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 

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 Sunday. Seas are forecast
to build to 6-8 ft with these winds. 


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


A surface low of 1008 mb is analyzed within the monsoon trough 
at 11N107W. A cluster of moderate to isolated strong convection
is noted within 120 nm W semicircle of the low center. Scattered
moderate isolated strong convection is seen elsewhere from 07N 
to 14N between 106W and 111W. 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 12N111W on Thu and 
near 11N116W on Fri. 

Another surface low pressure is near 17N118W. Convection is
limited in association with this low. Satellite imagery shows 
only scattered moderate convection within 75 nm S semicircle of
low center. The most recent ASCAT pass provided observations on 
fresh to strong winds within 120 nm NE semicircle 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 

The remnants of former tropical cyclone Jova continue to spin 
near 18.5N132W with a central pressure of 1009 mb. A swirl of low
clouds is still noted 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 SE
of a line from 11N105W to 06N115W to another line from 11N102W 
to 06N108W. These seas will propagate westward, and subside to 
less than 8 ft on Friday. 


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Page last modified: Wednesday, 16-Aug-2017 21:40:01 UTC