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Hurricane Hilary Advisory Number 11
NWS National Hurricane Center Miami FL EP092023
900 PM MDT Fri Aug 18 2023
...LIFE-THREATENING AND POTENTIALLY CATASTROPHIC FLOODING LIKELY
OVER MUCH OF BAJA CALIFORNIA AND THE SOUTHWESTERN UNITED STATES
THIS WEEKEND AND EARLY NEXT WEEK...
...TROPICAL STORM WARNINGS EXTENDED NORTHWARD INTO SOUTHERN
SUMMARY OF 900 PM MDT...0300 UTC...INFORMATION
ABOUT 285 MI...460 KM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
ABOUT 355 MI...570 KM S OF CABO SAN LAZARO MEXICO
MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H
PRESENT MOVEMENT...NNW OR 335 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...948 MB...28.00 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The Tropical Storm Watch from the California/Mexico border to Point
Mugu, including Catalina Island has been changed to a Tropical
The government of Mexico has issued a Tropical Storm Warning along
the west coast of the Baja Peninsula peninsula from Cabo San Quintin
to the California/Mexico border.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Warning is in effect for...
* Baja California peninsula from Punta Abreojos to Cabo San Quintin
A Hurricane Watch is in effect for...
* Baja California peninsula north of Cabo San Quintin to Ensenada
A Tropical Storm Warning is in effect for...
* Baja California peninsula from Punta Abreojos southward
* Baja California peninsula entire east coast
* Baja California from Cabo San Quintin northward to the
* Mainland Mexico north of Guaymas
* California/Mexico border to Point Mugu
* Catalina Island
A Tropical Storm Watch is in effect for...
* Mainland Mexico from Huatabampito to Guaymas
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. A warning is typically issued
36 hours before the anticipated first occurrence of
tropical-storm-force winds, conditions that make outside
preparations difficult or dangerous. Preparations to protect life
and property should be rushed to completion.
A Hurricane Watch means that hurricane conditions are possible
within the watch area. A watch is typically issued 48 hours
before the anticipated first occurrence of tropical-storm-force
winds, conditions that make outside preparations difficult or
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.
Interests in the southwestern U.S. should monitor the progress of
For storm information specific to your area in the United States,
including possible inland watches and warnings, please monitor
products issued by your local National Weather Service forecast
office. For storm information specific to your area outside of the
United States, please monitor products issued by your national
DISCUSSION AND OUTLOOK
At 900 PM MDT (0300 UTC), the center of Hurricane Hilary was located
near latitude 19.7 North, longitude 112.7 West. Hilary is moving
toward the north-northwest near 13 mph (20 km/h), and this motion
is expected to continue through Saturday. A faster motion toward
the north-northwest and north is expected Saturday night and
Sunday. On the forecast track, the center of Hilary will move close
to the west-central coast of the Baja California peninsula on
Sunday and reach southern California by Sunday night.
Maximum sustained winds are near 130 mph (215 km/h) with higher
gusts. Hilary is a category 4 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Weakening is expected to begin by Saturday,
but Hilary will still be a hurricane when it approaches the west
coast of the Baja California peninsula Saturday night and Sunday.
Hilary is expected to weaken to a tropical storm by late Sunday
before it reaches southern California.
Hurricane-force winds extend outward up to 50 miles (85 km) from the
center and tropical-storm-force winds extend outward up to 255 miles
The estimated minimum central pressure is 948 mb (28.00 inches).
HAZARDS AFFECTING LAND
Key messages for Hilary can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDEP4 and WMO header WTPZ44 KNHC
and on the web at hurricanes.gov/text/MIATCDEP4.shtml.
RAINFALL: Hilary is expected to produce rainfall amounts of 3 to 6
inches, with isolated maximum amounts up to 10 inches, across
portions of the Baja California Peninsula through Sunday night.
Flash and urban flooding, locally catastrophic, will be likely,
especially in the northern portions of the peninsula.
Heavy rainfall in association with Hilary is expected to impact the
Southwestern United States through early next week, peaking on
Sunday and Monday. 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 locally catastrophic
flooding will be likely. Elsewhere across portions of the Western
United States, rainfall totals of 1 to 3 inches are expected,
resulting in localized flash flooding.
WIND: Hurricane conditions are expected within the hurricane
warning area beginning Saturday night and are possible within the
hurricane watch by early Sunday. Tropical storm conditions are
expected within the warning area tonight, and are possible within
the watch area in Mexico on Saturday and Sunday. Tropical storm
conditions are expected to begin in southern California on Sunday.
STORM SURGE: A dangerous storm surge is likely to produce coastal
flooding along the western Baja California peninsula of Mexico near
where the center passes the coast in areas of onshore winds, or
east of the center if Hilary makes landfall. The surge will be
accompanied by large and destructive waves.
SURF: Large swells generated by Hilary will 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
consult products from your local weather office.
Next intermediate advisory at 1200 AM MDT.
Next complete advisory at 300 AM MDT.