000
AXPZ20 KNHC 181605
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Thu Oct 18 2018

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 
1515 UTC.

...SPECIAL FEATURE...

Showers and thunderstorms associated with an area of low 
pressure located south of the Gulf of Tehuantepec have changed 
little in organization overnight. However, environmental 
conditions appear conducive for development once the system 
moves west of the Gulf of Tehuantepec, and a tropical depression 
or tropical storm is likely to form during the next day or two. 
The low is forecast to move generally west-northwestward for the 
next several days, near or just offshore the coast of southern 
Mexico. In the meantime, gap winds in the range of 20 to 30 kt 
are occurring in the Gulf of Tehuantepec just ahead of the low 
pressure. Likely assisted by the gap wind event, the low is 
forecast to intensify by early Friday, resulting in gale force 
winds within 150 nm of the low center. Further intensification 
is forecast Friday with winds reaching 40 kt with seas to 16 ft. 
See the East Pacific Tropical Weather Outlook under AWIPS/WMO 
header MIATWOEP/ABPZ20 KNHC for further details.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from 13N90W to a low near 13N94W to 
12N115W to 09N121W to 11N134W to 10N140W. Scattered moderate 
convection from 09N to 16N E of 102W, from 09N to 13N between 
114W and 120W, and from 07N to 16N between 130W and 138W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

The pressure gradient between a trough along western Mexico and 
surface ridging west of the Revillagigedo Islands will maintain 
gentle to moderate NW winds W of Baja California through early 
Monday. Seas over this region will be 4-6 ft through Sun. 
Afterwars, seas are forecast to increase in the offshores of 
Baja California Sur as a low/possible tropical cyclone 
approaches from the SE.

Moderate to fresh NW winds with seas to 4 ft are forecast for 
the Gulf of California through Sat. Winds and seas will decrease 
Sun and Mon.

A current gap wind event in the Gulf of Tehuantepec, with winds 
to 25-30 kt, is forecast to merge with the area of low pressure 
mentioned in the Special Features section by tonight.

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

Fresh to locally strong SW monsoonal flow will continue south of 
El Salvador, Nicaragua and Guatemala through Fri with seas to 10 
ft. Near gale force winds are expected today in Guatemala waters 
as a low pressure area, possible tropical cyclone, deepens south 
of Mexico. Widespread showers and thunderstorms associated with 
this low pressure area are expected to continue across much of 
Central America and adjacent Pacific coastal waters, spreading 
well inland during the next two days. 
  
REMAINDER OF THE AREA...

A surface trough extending from 30N138W to 25N140W will 
dissipate today. Long period NW swell associated with the former 
front will cause seas to build to between 8 and 10 ft N of 12N W 
of 131W.

$$
NR