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BULLETIN
Tropical Storm Hilary Advisory Number  17
NWS National Hurricane Center Miami FL       EP092023
800 AM PDT Sun Aug 20 2023
 
...HILARY VERY NEAR THE WEST COAST OF BAJA CALIFORNIA...
...CATASTROPHIC AND LIFE-THREATENING FLOODING LIKELY OVER BAJA
CALIFORNIA AND PORTIONS OF THE SOUTHWESTERN U.S. THROUGH MONDAY...
 
 
SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...29.7N 115.9W
ABOUT 220 MI...350 KM SSE OF SAN DIEGO CALIFORNIA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NNW OR 345 DEGREES AT 25 MPH...41 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES
 
 
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
 
The government of Mexico has discontinued the Hurricane Watch and
downgraded the Hurricane Warning to a Tropical Storm Warning for
the Baja California Peninsula.
 
The government of Mexico has discontinued the Tropical Storm
Warning south of Puerto San Andresito on the west coast and south
of Loreto on the east coast of the Baja California Peninsula.
 
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
 
A Tropical Storm Warning is in effect for...
* Baja California peninsula west coast from Puerto San
Andresito northward
* Baja California peninsula east coast from Loreto northward
* Mainland Mexico north of Guaymas
* California/Mexico border to Point Mugu
* Catalina Island
 
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning.
 
Interests elsewhere in the southwestern U.S. should monitor the
progress of Hilary.
 
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 meteorological service.
 
 
DISCUSSION AND OUTLOOK
----------------------
At 800 AM PDT (1500 UTC), the center of Tropical Storm Hilary was
located near latitude 29.7 North, longitude 115.9 West. Hilary is
moving quickly toward the north-northwest near 25 mph (41 km/h). 
Hilary is expected to accelerate even more as it moves 
north-northwestward to northward during the next day or so.  On the 
forecast track, the center of Hilary will move near or over the 
northern portion of the Baja California Peninsula during the next 
few hours, and then move across southern California this afternoon.
 
Maximum sustained winds are near 70 mph (110 km/h) with higher
gusts.  Weakening is expected, but Hilary is expected to remain
a tropical storm before it reaches southern California.
 
Tropical-storm-force winds extend outward up to 240 miles (390 km)
from the center.
 
The estimated minimum central pressure is 984 mb (29.06 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 storm total rainfall 
amounts of 3 to 6 inches, with maximum amounts up to 10 inches, 
across portions of the northern Baja California Peninsula through 
tonight. Flash and urban flooding, locally catastrophic, is 
expected.

Intense heavy rainfall associated with Hilary is expected across the 
Southwestern United States through early Monday morning. Rainfall 
amounts of 3 to 6 inches, with isolated maximum amounts of 10 
inches, are expected across portions of southern California and 
southern Nevada leading to dangerous to catastrophic flooding. 
Across portions of Oregon and Idaho, rainfall totals of 1 to 3 
inches with local maxima to 5 inches are expected through Tuesday 
morning, resulting in localized, some significant, flash flooding.

A list of rainfall observations compiled by the NOAA Weather 
Prediction Center for this storm can be found at: 
www.wpc.ncep.noaa.gov/discussions/nfdscc4.html
 
WIND:  Tropical storm conditions are occurring within the tropical 
storm warning area within the Baja California Peninsula and will 
continue through today.  Tropical storm conditions are expected to 
begin in southern California this afternoon.
 
Winds could be particularly strong and gusty in and near areas of
elevated terrain.  Higher gusts are expected well inland and will
persist even after the system becomes post-tropical.
 
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.  Coastal flooding is
possible along the northern coast of the Gulf of California today
through early Monday.
 
TORNADOES: A couple tornadoes are possible through this evening over 
southeast California, western Arizona, southern Nevada, and far 
southwest Utah.
 
SURF:  Large swells generated by Hilary will affect portions of the
Baja California Peninsula and southern California over the next
day or so.  These swells are likely to cause life-threatening
surf and rip current conditions.  Please consult products from your
local weather office.
 
 
NEXT ADVISORY
-------------
Next intermediate advisory at 1100 AM PDT.
Next complete advisory at 200 PM PDT.
 
$$
Forecaster Cangialosi
 
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