000
AXPZ20 KNHC 302116
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Thu Sep 30 2021

Tropical Weather Discussion for the eastern Pacific Ocean from
03.4S to 30N, east of 120W including the Gulf of California, and
from the Equator to 30N, between 120W and 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.

...TROPICAL WAVES...

A tropical wave extends its axis from a 1010 mb low pres near 
09N93W to 19N92W. Scattered moderate convection is noted S of 
10N between 90W-100W.

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

The monsoon trough extends from 08N83W to 1010 mb low pres near 
09N93W to 10N99W, then resumes near 18N104W to 1010 mb low pres 
near 17N106W to 12N133W. The ITCZ continues from that point to 
12N140W. Scattered moderate convection is observed from 04N to 
13N and E of 100W, from 15N to 20N between 104W and 111W, and 
from 08N to 15N and W of 114W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Showers and thunderstorms have increased today in association 
with an area of low pressure located a couple of hundred miles 
west-southwest of Manzanillo, Mexico. Associated winds are 
mainly gentle to moderate, and nearby seas are 5 to 6 ft. 
Moderate NW winds are noted offshore of Baja California, while 
mainly gentle to moderate winds prevail elsewhere offshore of 
Mexico. NW swell is supporting seas of 7 to 9 ft west of Baja 
California, with the highest seas north of Punta Eugenia. Seas 
are mainly 4 to 6 ft elsewhere in mixed long period swell, except
3 ft or less in the Gulf of California north of the entrance 
area.

For the forecast, some slow development is possible with the low
near Manzanillo through early Friday before it reaches an area 
of stronger upper-level winds. It will continue moving toward 
the west-northwest at 5 to 10 kt. Moderate NW-N winds offshore 
of Baja California will diminish by the end of the week. Moderate
to fresh gap winds may develop in the Gulf of Tehuantepec this 
weekend, increasing to fresh to strong by Sun night and continue
to pulse at nighttime through early next week. Otherwise, light 
to gentle winds will prevail. Large NW swell propagating 
southeast and offshore of Baja California will subside by the end
of the week. 

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

Light to gentle E-SE winds are noted north of the monsoon 
trough, with moderate S-SW winds south of the monsoon trough. 
Seas are mainly in the 4 to 6 ft range in mixed long period 
mixed swell.

For the forecast, winds in the Papagayo region will occasionally
pulse to moderate at nighttime. Otherwise, light to gentle winds
will prevail north of the monsoon trough, with mainly moderate 
S-SW winds south of the monsoon trough. A moderate cross-
equatorial SW swell will propagate through the regional waters 
during the next several days. 

REMAINDER OF THE AREA...

High pressure prevails across the remainder of the basin. A set
of NW-N swell supports seas of 7 to 9 ft north of 22N, while an 
area of 7 to 9 ft in fresh trades mixed with the swell is from 
13N to 23N west of 122W. Seas are mainly 5 to 7 ft across the 
remainder of the open waters. Mainly moderate to locally fresh 
trades prevail elsewhere north of the convergence zone, with 
moderate southerly flow south of the monsoon trough. 

For the forecast, the NW-N swell will continue to propagate 
through the northern and central waters through tonight while 
gradually decaying. Reinforcing fresh northerly swell will pump 
seas back up to around 8 ft near 30N between 125W and 135W into 
the weekend. Trades are forecast to diminish this weekend into 
early next week as the pressure gradient loosens.

$$
ERA