000
AXPZ20 KNHC 191623
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Sat Aug 19 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 1200 UTC surface analysis and satellite imagery through
1530 UTC.

...SPECIAL FEATURES...

Hurricane Hilary is centered near 22.3N 113.5W at 19/1200 UTC, 
moving north-northwest at 14 kt. Estimated minimum central 
pressure is 947 mb. Maximum sustained wind speed is 110 kt with 
gusts to 135 kt. Numerous moderate to strong within the 180 nm E
semicircle. Scattered to locally numerous moderate to strong
convection is elsewhere within 270 nm of the center of Hilary.

Seas in excess of 12 ft extend to 270 nm in the NE quadrant and  
to 450 nm in the SE quadrant and to 330 nm in the SW quadrant 
and to 300 nm in the NW quadrant of the center, including within
the Gulf of California

Hilary will maintain hurricane strength as it moves along the 
west coast of Baja California, before diminishing to tropical 
storm strength it moves inland over the northern coast of Baja 
California Norte on Sun. 

Hilary is expected to produce storm total rainfall 
amounts of 3 to 6 inches, with isolated maximum amounts up to 10 
inches, across portions of the northern Baja California Peninsula 
through Sunday night. Flash and urban flooding, locally 
catastrophic, is expected, especially in the northern portions of 
the peninsula.

Heavy rainfall is expected across the Southwestern United States, 
peaking late tonight through Sunday night. Rainfall amounts of 3 to 
6 inches, with isolated amounts of 10 inches, are expected across 
portions of southern California and southern Nevada. Dangerous to 
catastrophic flooding is expected.  Elsewhere across portions of the 
Western United States, rainfall totals of 1 to 3 inches are 
expected, resulting in localized, some significant, flash flooding.

Large swells generated by Hilary will continue to affect 
portions of the coast of southwestern Mexico, the Baja California
peninsula, and southern California over the next few days. These
swells are likely to cause life-threatening surf and rip current
conditions.

Please 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 
Hilary NHC Forecast/Advisory and Public Advisory at 
www.hurricanes.gov for more details.

...TROPICAL WAVES...

A tropical wave is along 98W north of 03N moving west at 10-15 
kt. Scattered moderate isolated strong convection is from 10N to
15N between 95W and 100W.

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

The monsoon trough axis extends from 09N83W to 07N106W and from 
12N119W to 08N140W. Aside from convection noted in the tropical
waves section, scattered moderate isolated strong convection is
from 03N to 06N east of 80W, including offshore Colombia. 
Scattered moderate convection is from 08N to 10N between 115W and
123W. 

...OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
 
Please see the Special Features section for information on Hurricane
Hilary.

Outside of Hurricane Hilary, a small area of northerly gap winds
of 15 to 20 kt is in the Gulf of Tehuantepec as a result of the 
pressure gradient between high pressure in the Gulf of Mexico and
lower pressure across the East Pacific. Gentle to moderate E to 
NE winds and seas of 4-7 ft prevail elsewhere. Active convection described
above covers a large area between Tehuantepec and 103W, 
associated with the tropical wave.

For the forecast, winds and seas will gradually diminish over
Mexican offshore waters through Mon in the wake of Hilary. Fresh
to strong gap winds will pulse across the Gulf of Tehuantepec
through mid week, mainly at night. Looking ahead, another area 
of low pressure has a low chance of development off southern 
Mexico through mid-week.

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

Fresh northeast to east winds are pulsing across the Papagayo
region this morning, with seas to 6 ft. Gentle winds are noted 
elsewhere, with mostly 3 to 5 ft seas in SW swell.

For the forecast, moderate to fresh E winds will pulse across 
the Gulf of Papagayo through this morning and again on Sun. 
Light to gentle breezes and slight to moderate seas will persist 
elsewhere into Sun. Looking ahead, SW winds will increase off 
Costa Rica and western Panama Mon and Tue, then diminish through 
mid week as the monsoon trough lifts northward. Elsewhere across 
the offshore forecast waters of Central and South America, gentle
to moderate winds and moderate seas are expected through the 
period.

...REMAINDER OF THE AREA...

The remnant low of former tropical cyclone Fernanda is west of 
140W. Fresh to strong E winds and 8-9 ft seas are from 17N to 
19N west of 139W, behind the exiting remnants of Fernanda. 
Overnight scatterometer data also captured fresh SW winds from 
08N to 12N between 107W and 117W flowing towards Hilary. A ridge 
dominates remaining waters north of 20N and west of 120W, 
supporting gentle to moderate winds with 5-7 ft seas.

For the forecast, the winds and seas associated with the remnant low
of Fernanda will diminish over the next six to twelve hours and
shift west of 140W. SW winds will start to increase south of the
monsoon trough east of 110W Mon and Tue with building seas.

$$
Mahoney/Stripling