

000 

WGUS56 KSGX 180619

FFWSGX

CAC059-180745-



BULLETIN - EAS ACTIVATION REQUESTED

FLASH FLOOD WARNING

NATIONAL WEATHER SERVICE SAN DIEGO CA

1015 PM PST FRI FEB 17 2006



THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A



* FLASH FLOOD WARNING FOR...

  NORTH CENTRAL ORANGE COUNTY IN SOUTHWEST CALIFORNIA

  THIS INCLUDES THE CITY OF YORBA LINDA



* UNTIL 1145 PM PST



* AT 1014 PM PST...FLASH FLOODING WAS REPORTED FROM THUNDERSTORMS

  ALONG A LINE EXTENDING FROM 18 MILES NORTHEAST OF YORBA LINDA TO 10

  MILES SOUTH OF SILVERADO CANYON...OR ALONG A LINE EXTENDING FROM

  RANCHO CUCAMONGA TO MISSION VIEJO...MOVING EAST AT 10 MPH.



* THUNDERSTORMS PRODUCING FLASH FLOODING WILL BE NEAR...

  RURAL EASTERN ORANGE COUNTY AT 1030 PM PST



IN ADDITION TO FLASH FLOODING...RAINFALL IS EXPECTED TO CAUSE DEBRIS 

FLOWS IN THE WATERSHEDS BURNED BY THE SIERRA AND YORBA LINDA FIRES. 

THE SOILS IN A BURN SCAR ARE HIGHLY ERODIBLE SO FLOOD WATERS CAN 

CONTAIN SIGNIFICANT AMOUNTS OF ASH...MUD... BOULDERS...AND 

VEGETATION.  WITHIN THE BURNED AREA AND DOWNSTREAM... THE POWERFUL 

FORCE OF RUSHING WATER...SOIL...AND ROCK CAN DESTROY 

CULVERTS...BRIDGES...ROADWAYS...AND STRUCTURES...AND CAN CAUSE 

INJURY OR DEATH IF CARE IS NOT TAKEN.



DRAINAGES IN FEATHERLY REGIONAL PARK...STREAM CROSSINGS ON STATE 

HIGHWAYS 91 AND 241 AND GYPSUM CANYON ROAD...AND SANTIAGO RESERVOIR 

COULD BE IMPACTED BY THESE EVENTS.  A SHORT PERIOD OF MODERATE 

RAINFALL ON THE BURNED WATERSHEDS CAN LEAD TO FLASH FLOODS AND 

DEBRIS FLOWS. RAINFALL THAT IS NORMALLY ABSORBED BY VEGETATION CAN 

RUN OFF ALMOST INSTANTLY. THIS CAUSES CREEKS AND DRAINAGE AREAS TO 

FLOOD MUCH SOONER DURING A STORM...AND WITH MORE WATER THAN IS 

NORMAL.



IN THE YORBA LINDA BURN AREA ACCORDING TO THRESHOLDS PROVIDED BY 

THE USGS. AREAS AFFECTED INCLUDE PARTS OF TELEGRAPH CANYON ROAD AND 

CARBON CANYON ROAD.



$$



IN ADDITION TO FLASH FLOODING...RAINFALL IS EXPECTED TO CAUSE DEBRIS 

FLOWS...MUD SLIDES...AND ROCK SLIDES WITH THIS STORM. MUD SLIDES AND 

ROCK SLIDES CAN POTENTIALLY TRAP AND KILL PEOPLE CAUGHT IN THEIR 

PATH.



RESIDENTS AND MOTORISTS IN AND BELOW RECENTLY BURNED AREAS SHOULD BE

ALERT TO HEAVY MUD AND DEBRIS FLOWS WHICH MAY BLOCK ROADS AND

CULVERTS. POTENTIALLY DANGEROUS FLOODING AND PROPERTY LOSS COULD

RESULT IN AREAS WHERE RUNOFF IS RESTRICTED OR BLOCKED.



LAT...LON 3394 11778 3378 11776 3374 11763 3380 11760

      3389 11769



$$



RB/MGM

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