990 
AXPZ20 KNHC 210400
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sat Oct 21 2023

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 0000 UTC surface analysis and satellite imagery through
0350 UTC.

...SPECIAL FEATURES...

Major Hurricane Norma is centered near 20.8N 109.9W at 21/0300 
UTC, moving north-northwest at 8 kt. Estimated minimum central 
pressure is 955 mb. Maximum sustained wind speed is 105 kt with 
gusts to 130 kt. Peak seas are 36 ft. Numerous moderate to strong
convection is noted from 18N to 23N between 107W and 113W. 
Scattered moderate convection is elsewhere from 17N to 28N 
between 105W and 114W. On the forecast track, Norma is expected 
to move over the southern portion of Baja California Sur within 
the hurricane warning area on Saturday. Norma is forecast to move
toward the west coast of Mexico on Sunday and Sunday night and 
move inland within the tropical storm watch area on Monday. Some 
gradual weakening is expected during the next day or so, but 
Norma is expected to be a hurricane when it moves near or over 
the southern portion of Baja California Sur. Weakening is 
forecast to continue through early next week. Please consult 
products from your local weather office and read the latest HIGH 
SEAS FORECAST issued by the National Hurricane Center at website 
- https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest 
Norma NHC Forecast/Advisory and Public Advisory at 
www.hurricanes.gov for more details.

South of Southern Mexico (EP91): The circulation associated with
a broad area of low pressure located several hundred miles south
of the Gulf of Tehuantepec is currently producing limited shower
and thunderstorm activity well to the west of its center due to 
strong upper-level winds, but environmental conditions are 
expected to become more conducive for development over the next 
couple of days. A tropical depression is likely to form later 
this weekend or early next week. The system is forecast to 
meander during the next couple of days and then drift generally 
northward late this weekend and into early next week. This system
has a medium chance of tropical cyclone formation through 48 
hours, and a high chance through 7 days. Please read the latest 
NHC Tropical Weather Outlook at www.hurricanes.gov for details.

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

The monsoon trough extends from the coast of Costa Rica near
10N86W to low pres near 09N96W 1007 mb to 10N105W, then resumes 
well SW of Norma near 09N124W to 06N129W. The ITCZ continues from
that point to 11N140W. Numerous moderate to strong convection is
from 04N to 10N E of 90W. Scattered moderate convection is noted
from 05N to 13N between 96W and 114W.
 
...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Please see the SPECIAL FEATURES section above for more details
on Major Hurricane Norma and Invest EP91.

Aside from Hurricane Norma, a ridge extends W of the Baja 
California offshore waters. Gentle to moderate NW winds prevail in
the Baja California offshore waters N of Cabo San Lazaro along
with NW swell with seas ranging from 8 to 11 ft. A plume of strong
winds prevails across the Gulf of Tehuantepec with seas to 8 ft.
In the Gulf of California, light to gentle variable winds 
continue N of 26N with seas to 3 ft. To the south of 26N, 5 to 8
ft seas are ongoing due to the proximity of Norma. In the 
remaining SW Mexican offshore waters, winds are gentle with seas
of 7 to 11 ft in mixed swell due to Norma.

For the forecast, Norma will move to 21.9N 110.1W Sat morning, 
23.0N 109.9W Sat evening, 23.6N 109.4W Sun morning, weaken to a 
tropical storm near 23.9N 108.6W Sun evening, 24.3N 107.6W Mon 
morning, and move inland and weaken to a tropical depression near
24.8N 106.5W Mon evening. Norma will dissipate late Tue. 

Elsewhere, the strong winds over the Gulf of Tehuantepec will
diminish by Sat afternoon. Fresh to locally strong winds can be 
expected across the Baja California offshore waters this weekend 
along with large NW swell. This will result in confused and 
hazardous seas as it mixes with swells generated by Norma. The 
swell will begin to subside by Sunday, with a new set of NW swell
entering the offshores of Baja California early next week.

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

Please see the SPECIAL FEATURES section above for more details
on Invest EP91.

A broad area of low pressure located well south of the Gulf of 
Tehuantepec (Invest EP91), is generating SE to E winds across the  
offshore waters of Guatemala and El Salvador. Otherwise, light 
to gentle winds prevail N of the monsoon trough in the Central 
American offshore waters. Seas range 5 to 7 ft with the higher 
seas close to EP91. South of the monsoon trough, gentle to 
moderate W to SW winds are noted with seas 5 to 7 ft within S to 
SW swell. Strong thunderstorms with heavy rainfall continues 
across offshore Colombia, Panama, and Costa Rica. 

For the forecast, light to gentle winds will prevail N of the 
monsoon trough with gentle to moderate winds S of the monsoon 
trough through the weekend. Winds will begin to increase to 
locally moderate across the South America and Galapagos Islands 
offshore waters briefly early next week. Seas may build slightly 
in SW swell offshore Ecuador to the Galapagos Islands by the end 
of the weekend, spreading across the rest of the offshore waters 
from W to E by early next week as NW swell arrives. EP91 has the
potential to develop into a tropical depression later this 
weekend or early next week. The system is forecast to meander 
during the next couple of days and then drift generally northward
late this weekend and into early next week.

...REMAINDER OF THE AREA...

Please see the SPECIAL FEATURES section above for more details 
on Major Hurricane Norma and Invest EP91.

Surface ridging extends across the northern forecast waters, N 
of 20N and W of 119W anchored by a pair of 1016 mb high pres
centers. Moderate SW winds are noted in the NW corner of the 
area ahead of an approaching cold front, N of 25N and W of 133W.
Light to gentle winds prevail elsewhere across this area N of 
the monsoon trough and W of 120W. S of the monsoon trough, gentle
to moderate S to SW winds are noted.

Large NW swell continues to propagate across most of the waters.
Peak seas are around 11 ft. Seas of 8 ft or greater covers the 
majority of the waters W of 93W. Confused and hazardous seas 
will result from the combination of the NW swell, SW swell moving
N of the Equator, and swells generated by Norma through the end 
of the week and into the weekend. Seas will gradually decay from 
west to east tonight through the weekend. Please read the latest 
NHC High Seas Forecast at website www.hurricanes.gov/marine for 
more details. 

For the forecast, other than the large NW swell event and low
pressure (EP91), Norma will move to 21.9N 110.1W Sat morning, 
23.0N 109.9W Sat evening, 23.6N 109.4W Sun morning, weaken to a 
tropical storm near 23.9N 108.6W Sun evening, 24.3N 107.6W Mon 
morning, and move inland and weaken to a tropical depression near
24.8N 106.5W Mon evening. Norma will dissipate late Tue. 

Elsewhere, a weak pressure pattern will support mainly gentle to
moderate winds across the open waters through the weekend. Winds
may increase moderate to locally fresh by early next week as 
high pressure builds N of the area and tightens the pressure 
gradient. Meanwhile, a new set of NW swell is forecast to spread
S of 30N to the E of 130W by early next week, potentially 
building seas to 7-10 ft N of 24N.

$$
Ramos