000
AXPZ20 KNHC 281519
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1519 UTC Thu Sep 28 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
1500 UTC.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...         

The monsoon trough extends from 08N78W to 15N95W to 1008 mb low 
pressure near 13N115W to 10N140W. Scattered moderate convection
from 13N to 16N between 94W and 96W. Scattered moderate
convection from 10N to 12N between 117W and 124W. 

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

Low pressure of 1007 mb persists south of the Gulf of 
Tehuantepec, supporting scattered moderate convection from 13N to
16N between 90W and 100W. This area of low pressure will 
remain off the coast of southern Mexico through Sunday. Fresh to
strong gap winds will develop over the Gulf of Tehuantepec by 
Sat night as high pressure ridging southward over the western 
Gulf of Mexico interacts with a broad area of developing low 
pressure over Central America.

Elsewhere, pressure gradient over the area remains low as the 
ridge to the north is still weakened by low pressure well to the 
north. This will support gentle to moderate breezes north of 16N 
through Sunday. Seas in the 3 to 5 ft foot range will prevail 
over the open waters through Sat. Winds and seas will then begin 
to increase as the ridge to the NW rebuilds. Northerly swell will
propagate into the waters west of Baja California Norte Sunday, 
building seas to 5 to 7 ft.


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

An active monsoon trough currently passes over Central America. 
The trough will remain close enough to the coast, either inland 
or just offshore, to produce active convection, primarily during 
the late afternoon and early evening hours, over portions of 
Central America as well as the adjacent coastal waters during the
next few days. Moderate SW to W winds are expected south of the 
trough through Sun. Long period SE to S swell will maintain 5 to 
6 ft seas west of Ecuador and south of the Equator during the 
same time frame. Looking ahead, broad 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.

REMAINDER OF THE AREA...

Low pressure of 1008 mb near 14N117W remains embedded within the
monsoon trough. However, both the intensity and areal coverage 
of convection associated with this feature have diminished during
the past 12 hours. The latest satellite-derived wind data 
indicate the wind field surrounding the low has become more 
subdued with maximum wind speeds decreasing to 20 kt or less. The
low is expected to continue weakening and become more elongated 
through tonight, as associated winds and seas gradually diminish.
Elsewhere, weak high pressure north of the area will support 
gentle to moderate trade winds across the region south of 20N. 
Looking ahead, northerly swell of 8 to 9 ft will propagate into 
the waters north of 25N between 120W and 130W Sun through Mon 
night. Farther south, southerly swell will move across the
equator, with seas to 7 ft south of 02N between 120W and 140W.

$$
Christensen