000
AXPZ20 KNHC 112256 AAA
TWDEP 

Tropical Weather Discussion...Updated
NWS National Hurricane Center Miami FL
2256 UTC Sun Sep 11 2022

Updated ITCZ/Monsoon Trough section

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
2245 UTC.

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

The monsoon trough axis extends from 12N86W northwestward to 
15N96W to low pressure near 17N104W 1008 mb, then southwestward to 
10N120W to 13N1128W and to beyond 13N140W. Scattered moderate to 
strong convection is from 04N to 09N between 80W-85W, within 120 nm 
north of the trough axis between 80W-87W. Scattered moderate 
to isolated strong convection is within 120 nm southwest of the 
trough axis between 95W-100W. Scattered moderate convection is from 
09N to 12N between 104W-112W, from 07N to 10N between 112W-119W, 
within 120 nm south of the trough axis between 128W-131W and within 
30 nm north of the trough axis west of 137W.
 
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

The remnant low of former tropical cyclone Kay is analyzed near 
30.5N122W with a pressure of 1009 mb. It is slowly moving to the 
southwest. Moderate to fresh winds are within 180 nm of the low in 
the NE, S, W and NW quadrants, and gentle to moderate winds are 
elsewhere around the low per a recent received ASCAT data pass. Seas 
are 6-7 ft north of 28N between 120W-128W. The low is forecast to 
continue to weaken as it slowly moves southwest to south of 30N 
through tonight. It will drift south-southeastward Mon and Mon night 
and weaken to a trough west of Baja California Tue.
 
Light to gentle variable winds are noted elsewhere across the 
offshore waters of Baja California, and in the Gulf of California
as noted in recent partial ASCAT data passes. The ASCAT data 
depicts an elongated southeast to northwest orientation of the 
cyclonic turning of winds over and to the south and southwest of
the Gulf of Tehuantepec region. This is the general area where a
section of the monsoon trough passes through of which its 
associated convection is described above under ITCZ/Monsoon 
Trough. Satellite imagery also shows similar cyclonic turning in 
the low and mid-level clouds present over those areas. The ASCAT 
data has a small swath of moderate to fresh east-southeast winds 
along and to within 90 nm offshore the coast of Guerrero. 
Abundant deep layer tropical moisture is leading to numerous 
clusters of scattered moderate to isolated strong convection over
the majority of the offshore forecast waters south of Jalisco.

For the forecast, the moderate to fresh northerly winds west of 
the low will continue through Tue and decrease in coverage. The
light to gentle variable winds over the offshore waters of Baja 
California Sur will increase to moderate speeds starting Tue as 
high pressure begins to build again across the region as the low
weakens to a trough. The broad cyclonic turning to the south and 
southwest of the Gulf of Tehuantepec and its related disorganized
convection is forecast to merge with the 1008 mb low pressure
that is along the monsoon trough near 17N104W. Environmental 
conditions are expected to be conducive for gradual development 
over the next several days. A tropical depression could form by 
the middle to latter part of this week, while the system moves 
slowly westward near the coast of southern and southwestern 
Mexico. The latest Tropical Weather Outlook gives this system a 
medium chance of tropical cyclone formation through 5 days.

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

Cross-equatorial long-period south to southwest swell continues 
to propagate through the forecast waters producing wave heights 
of 5-7 ft. Slighter higher wave heights of 6-8 ft are just beyond
the forecast waters. Latest ASCAT data passes indicate that mainly
gentle to moderate southwest to winds are over these waters.

For the forecast, gentle to moderate winds and moderate seas will 
continue through the forecast period. Cross-equatorial long-period 
south to southwest swell will continue into mid-week, but subside 
some. A very moist and unstable atmospheric environment will 
maintain active weather across most of the offshore waters through 
the period.

REMAINDER OF THE AREA...

A surface trough is just west of the area along 141W from 20N to
27N. No convection is occurring with this feature. Relatively 
weak high pressure is present over the area north of the monsoon
trough and west of 125W. The related rather light gradient is 
allowing for gentle to moderate trade winds over the waters north
of the monsoon trough and west of 110W where wave heights are
generally 5-7 ft ft. Moderate to fresh southerly winds are 
south of the monsoon trough along with seas of 7-9 ft due 
to a long-period southeast to south swell west of 103W, and 
long-period south to southwest swell east of 103W. The leading 
edge of 8 ft seas is about 120 nm to the southwest of the 
Galapagos Islands.

For the forecast, little change in marine conditions are 
expected over the next couple of days as the remnant low of Kay 
over the northeast part of the area gradually weakens to a trough
west Baja California Norte. A weak high pressure center will be 
over the northwest corner of the area near 30N140W. Moderate to 
fresh southwest winds and associated seas will continue south of 
the monsoon trough. Additional pulses of long-period southerly 
swell will propagate northward through most of the southern
waters into at least mid-week.

$$
Aguirre