000
AXPZ20 KNHC 232207
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sat Sep 23 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 1800 UTC surface analysis and satellite imagery through 
2100 UTC.

...SPECIAL FEATURES...

The elongated area of low pressure along the southwestern coast 
of Mexico has become better organized today, and afternoon 
scatterometer data indicated a well defined circulation center 
with wind to around 30 kt. The low has been classified as 
Tropical Depression Eighteen-E, near 18.4N 105.3W 1005 MB at 
2100 UTC moving an estimated NNW or 335 DEG at 4 KT. The 
depression is expected to gradually strengthen during the next 
two days, and become a tropical storm tonight near 18.8N105.5W. 
Seas will continue to grow to 8 ft and greater within 90 nm 
across the NE and 150 nm across the SW semicircles as this 
system moves NNW and just offshore of the Pacific coasts from 
Jalisco to Nayarit, and across portions of Las Tres Marias. 
Heavy rainfall causing flash floods and mudslides will also be 
possible along these coastal states extending well inland. See 
the latest NHC Forecast/Advisory under AWIPS/WMO headers 
MIATCMEP3/WTNT23 KNHC for more details.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...         

The monsoon trough stretches across most of the basin from 
northern Colombia near 09N73W TO 11.5N85W TO 15.5N102W, then 
resumes from near 15N110W to low pres near 12.5N127W 1010 MB to 
low pres near 13N138W 1010 MB to beyond 11N140W. Scattered 
moderate to strong convection is found from 03.5N TO 15.5N 
between 78W AND 90W, from 10N TO 15N between 92W AND 115W, and 
from 08.5N TO 12.5N between 125W AND 138W.
 
...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

A dissipating cold front extends from SW New Mexico SW across 
the central Gulf of California and Baja California to offshore 
of Cabo San Lazaro. High pressure building north of 25N behind 
the front will aid in freshening NW winds west of Baja 
California Norte through Sun. Elsewhere, expect increasing winds 
and seas near Tropical Depression Eighteen-E spreading 
northwestward from near Cabo Corrientes to the southern Gulf of 
California during the next few days.

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

An active monsoon trough near the coast of Central America from 
Guatemala to Panama will remain the focus for active convection 
in coastal waters the next few days. Expect SW winds south of 
the trough remain moderate to fresh this weekend. Farther south, 
gentle to moderate south to southwest winds will persist south 
of 05N through Monday. Long period SE swell from the Southern 
Hemisphere will maintain seas west of Ecuador and south of the 
Equator around 7 ft through Sunday.

REMAINDER OF THE AREA...

NW swell generated by strong winds north of the area is 
producing 7-8 ft seas N of 30N between 116W and 123W. Low pres 
near 13N138W will move west of the discussion area Sunday. High 
pres centered well N of the area and low pressure associated 
with the monsoon trough will maintain moderate to occasionally 
fresh trade winds W of 120W through Mon. Low pres passing north 
of the area will weaken the high, allowing trades to decrease 
later in the week. 

$$
Stripling