000
AXPZ20 KNHC 301515
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1515 UTC Sat Sep 30 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 1200 UTC surface analysis and satellite imagery through
1400 UTC.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...         

The monsoon trough extends across Central America near 12N85W to
a 1010 MB low pres near 13N110W to 1010 MB low pres near 12N132W to
beyond 10N140W. Scattered moderate convection is from 06N to 11N
between 80W and 95W, within 120 nm of the Mexico Coast S of 21N,
and within 180 nm S of the monsoon trough axis between 100W and 
120W. 

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

Gap winds will freshen over the Gulf of Tehuantepec the next 
couple of nights. Later next week a round of fresh to strong
winds through the Tehuantepec Gap is expected. Elsewhere, a 
ridge dominating the waters west of the Baja California 
Peninsula is producing gentle to moderate northerly winds and 
seas of 4-5 ft today. Northerly swell will propagate into the 
waters west of Baja California Norte starting Sunday morning, 
building seas to 6-8 ft Monday through Tuesday. Fresh to locally 
strong S-SW winds are expected over the northern Gulf of 
California Sunday night through Tuesday as low pressure develops 
north of the area. Seas are forecast to build to 5-6 ft over the 
northern Gulf with these winds.

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

An active monsoon trough is currently across Central America and
adjacent waters. The trough will remain close enough to the 
coast, either inland or just offshore, to produce active 
convection, primarily during the late afternoon and evening 
hours, over portions of Central America as well as the adjacent 
coastal waters during the next few days. 

Winds will begin to increase south of the monsoon trough this
weekend. Long period SW swell will propagate across the offshore
waters with seas of 5-7 ft through the weekend. Looking ahead, a
broad area of low pressure developing over Central America will 
cause monsoonal winds to surge to fresh to strong speeds west of 
Costa Rica from Sunday night through at least the middle of next 
week. Seas of 8 ft or higher will affect the waters beyond 200 nm
off the coast from Nicaragua to Guatemala beginning Monday
morning. A fresh SW swell train, with a leading edge period of 
20 to 22 seconds is forecast to reach the waters between Ecuador 
and the Galapagos Islands Tuesday night, building seas to 7-8 ft 
by Wednesday night and 8-10 ft by Thursday. 

REMAINDER OF THE AREA...
 
A ridge extends from 1022 mb high pressure located near 32N137W 
to near 23N118W. The pressure gradient between the ridge and the
monsoon trough is supporting gentle to moderate winds. A new area
of high pressure to the north will merge with the current high
later this weekend, bringing an increase in northerly winds to 
fresh to strong north of 25N and east of 131W. These winds
combined with northerly swell propagating into the waters north 
of 25N between 120W and 130W Sun through Mon night, will 
build seas to near 12 ft along 30N by Monday. Farther south, 
cross equatorial southerly swell will propagate across the waters
south of 02N between 105W and 135W by Tuesday, with seas 
building to 8-10 ft.

$$
Latto