202 
AXPZ20 KNHC 301616
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Wed Sep 30 2020

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
1530 UTC. 

...SPECIAL FEATURES...

Tropical Storm Marie is centered near 14.2N 113.8W at 30/1500
UTC moving W at 14 kt. Estimated minimum central pressure is 997
mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt.
Numerous moderate to strong convection is noted within 250 nm W
semicircle. Marie is forecast to steadily intensify as it moves 
on a westward to west- northwestward track during the next 
several days. The current forecast has Marie reaching hurricane 
intensity this evening. Please read the latest NHC Public 
Advisory at https://www.nhc.noaa.gov/text/MIATCPEP3.shtml and 
Forecast/ Advisory at 
https://www.nhc.noaa.gov/text/MIATCMEP3.shtml for more details. 

Gulf of Tehuantepec gale warning: The pressure gradient between 
high pressure building in the wake of a cold front in the Gulf of
Mexico and the eastern Pacific monsoon trough has tightened over
the area. This has increased winds funneling through the Chivela
Pass into the Gulf of Tehuantepec, and has started gale force 
gap winds across the Gulf of Tehuantepec. Seas will build to 
15-18 ft during this event. Gale force winds will continue 
through early Sat. Swell generated from this event is forecast to
reach 100W today. Please read the latest NWS High Seas Forecast 
issued by the National Hurricane Center at website 
https://www.nhc.noaa.gov/text/MIAHSFEP@.shtml for more details.

Of note, the 20-year climatology of the Tehuantepec gap wind
events indicates that on average 16 gale-force events and 5 
storm force-events occur in the Gulf of Tehuantepec each cold 
season. Most gale-force events occurred during November and 
December, while most storm-force winds occurred in January. 
Based on latest model trends and the present evolving synoptic 
scale setup, this forecast event most likely will supersede the 
previously recorded earliest start date of October 3rd.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from 10N86W to 14N106W, then resumes W
of T.S. Marie near 13N120W to 10N140W. Scattered moderate to
isolated strong convection is noted from 08N to 18N between 82W
and 108W. Scattered moderate convection is also located from 10N
to 14N between 120W and 140W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see above for more on the Gulf of Tehuantepec gales.

A weak ridge west of Baja California will maintain gentle to 
moderate NW to N winds across much of the region for the next few
days. Elsewhere, moderate to fresh east to southeast winds are 
generally expected across the waters from Las Tres Marias Islands
to Puerto Angel for the next few days as Marie moves away from 
the region. Marie is expected to become a large hurricane. The 
size of the system will generate a large area of seas greater 
than 8 ft spreading from swell out and away the cyclone center. 
This south swell will spread across the offshore waters west of 
the Baja California peninsula through the weekend.

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

Moderate to fresh southerly flow prevails S of the monsoon 
trough, with gentle winds north of the monsoon trough. Seas are
ranging from 5 to 7 ft. Some higher seas from gales in the
Tehuantepec region will spread into offshore waters of Guatemala
and El Salvador over the next few days.

REMAINDER OF THE AREA...

Please see Special Features section above for more information 
on T.S. Marie.

Outside of T.S. Marie, a weak pressure gradient prevails west of
120W, with gentle to moderate winds prevailing N of the monsoon 
trough to 20N, and gentle to moderate winds S of the monsoon 
trough. The cross equatorial swell across the waters S of 15N has
started to subside, however seas remain in the 5 to 7 ft range. 
These seas will continue to subside trough the middle of the 
week. New NW swell will propagate into the NW waters the middle 
of the week. Seas will build to 9 ft over the far NW waters by 
tonight. T.S. Marie is expected to become a large hurricane. The 
size of the system will generate a large area of seas greater 
than 8 ft spreading well away from the cyclone center. By 
Saturday, seas greater than 8 ft will cover much of the waters N 
of 10N and W of 115W. 

$$
KONARIK