000
AXPZ20 KNHC 030232
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Tue Oct 3 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.

...SPECIAL FEATURES...
A low pressure of 1004 mb is located near the Gulf of Tehuantepec
at 13.5N94.5W. Maximum sustained winds are 25 kt within 60 mm of
the low center. Shower and thunderstorm activity associated with
this area of low pressure have shown some signs of organization. 
Satellite imagery indicates a linear band of numerous moderate 
convection within about 60 nm NW of a line from 14N94W to 13N96W.
Environmental conditions are expected to be conducive for some 
additional development over the next couple of days while the 
system moves slowly west-northwestward or westward. The latest 
Tropical Weather Outlook gives this low pressure a medium change 
of formation through 48 hours. This low will bring an increase in
winds and building seas across the Tehuantepec area mainly on 
Tuesday.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...         

The monsoon trough is over Central America and extends from 
southern Guatemala to 1004 mb low pres near 13.5N94.5W to 
15N110W to 13N110W to 12N120W to 1008 mb low pres near 13N128W 
to beyond 10N140W. Outside from the convection associated with 
the aforementioned low pressure, clusters of moderate to strong 
convection are noted over parts of Central America near the trough
axis. Similar convection is along the mexican coast between 95W 
and 99W. Scattered moderate convection is from 10N to 15N between
97W and 102W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

Fresh to strong winds are expected across the Gulf of Tehuantepec
and downwind on Tuesday in association with a developing low
pressure area. Please, see Special Features for details. The 
combination of winds associated with the developing low pressure 
and long period SW swell, will generate a large area of seas of 8
to 12 ft or possibly higher S of 14N between 90W and 130W late on
Wednesday. This swell event will reach the offshore waters of 
Mexico, south of Cabo Corrientes late Wednesday into Thursday and
beyond.

Elsewhere, a ridge dominates the waters west of the Baja California
Peninsula producing gentle to moderate northerly winds and seas 
of 4 to 5 ft. Northerly swell propagating into the waters west 
of Baja California Norte, with seas of 9-11 ft based on a recent
altimeter pass will subside to 7-8 on Tuesday.

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

An active monsoon trough is currently across parts of Central 
America and adjacent waters with clusters of moderate to strong
convection. The trough will remain close enough to the coast, 
either inland or just offshore, to produce additional active 
convection over portions of Central America as well as the 
adjacent coastal waters during the next few days, with locally 
heavy rain possible.

Fresh to strong SW to W winds and seas of 8 to 11 ft are 
expected to affect the waters beyond 200 nm off the coast from 
Nicaragua to Guatemala through Wednesday. Winds and seas will 
also increase across the offshore waters of Panama and Costa Rica
Wednesday night into Thursday. The arrival of long period SW 
swell early Thursday will help build seas even more, reaching 8 
to 12 ft and locally higher offshore central America the
remainder of the work-week. 
 
Cross equatorial SW swell, with periods of 20 to 22 seconds are 
forecast to reach the waters between Ecuador and the Galapagos 
Islands Tuesday night, building seas to 7 to 8 ft by Wednesday 
night, shifting north of the area by Friday. 

REMAINDER OF THE AREA...
 
High pressure of 1023 mb centered N of the area near 35N137W 
extends a ridge across the north waters N of 20N W of 120W. The 
pressure gradient between this area of high pressure and the 
monsoon trough is supporting moderate to fresh NE winds N of 15N 
W of 130W. The pressure gradient between the area of high 
pressure and low pressure over the SW United States and NW Mexico
is producing fresh to strong N winds north of 28N between 123W 
and 129W. Associated northerly swell propagating into the northern
waters has built seas 8 to 12 ft over this area as far south as 
25N between 118W and 131W. An altimeter pass indicates seas to
12 ft near 30N120W. Winds over this area will decrease through 
tonight, with associated seas 8 ft or higher subsiding below 8 
ft by early Wednesday. A pair of low pressure areas along the
monsoon trough are helping to generate 8 ft or higher from 10N 
to 13N between 135W and 138W, and from 11N to 13N between 125W 
and 128W. 

Cross equatorial southerly swell will spread across the waters 
south of 02N between 105W and 135W by Tuesday, with seas building
to 8 to 10 ft. This swell event will reach as far north as 14N 
between 90W and 130W by late Wednesday.

$$
GR