FLOOD WATCH FOR FLASH FLOODING IN EFFECT FROM 6 AM TUESDAY

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FLOOD WATCH FOR FLASH FLOODING IN EFFECT FROM 6 AM TUESDAY

NATIONAL WEATHER SERVICE SAN DIEGO CA
800 PM PST SUN DEC 26 2004

...FLOOD WATCH FOR FLASH FLOODING IN EFFECT FROM 6 AM TUESDAY
MORNING UNTIL 6 PM WEDNESDAY EVENING...

FOR ORANGE COUNTY COASTAL AREAS-
SAN DIEGO COUNTY COASTAL AREAS-
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SAN DIEGO COUNTY VALLEYS-
SAN BERNARDINO COUNTY MOUNTAINS-
RIVERSIDE COUNTY MOUNTAINS-
SANTA ANA MOUNTAINS AND FOOTHILLS-
SAN DIEGO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-
COACHELLA VALLEY-
SAN DIEGO COUNTY DESERTS...

A STRONG PACIFIC STORM SYSTEM WILL MOVE SLOWLY SOUTH...OFF THE
CALIFORNIA COAST. THE SYSTEM WILL PICK UP LARGE AMOUNTS OF MOISTURE
AND IS EXPECTED TO PRODUCE VERY HEAVY RAINFALL...ESPECIALLY ON SOUTH
AND SOUTHWEST FACING COASTAL SLOPES BEGINNING MONDAY AND CONTINUING
INTO WEDNESDAY. SHOWERS COULD START AS EARLY AS LATE TONIGHT...BUT
THE HEAVIER RAIN WILL MOVE INTO THE AREA MONDAY NIGHT AND TUESDAY.
DUE TO THE EXTENDED DURATION OF THE EVENT...THERE WILL BE A THREAT
OF FLOODING AND MUDSLIDES... ESPECIALLY IN AND BELOW BURN AREAS.
EVEN DESERT AREAS WILL LIKELY GET SUBSTANTIAL RAIN DUE TO THE DEEP
MOISTURE AND SOUTH TO SOUTHEAST FLOW IN ADVANCE OF THE STORM.

RAINFALL AMOUNTS BETWEEN MONDAY AND WEDNESDAY ARE EXPECTED TO BE
BETWEEN 1 AND 2 INCHES IN THE DESERTS...2 TO 4 INCHES IN MOST
COASTAL AND VALLEY AREAS...AND 4 TO 6 INCHES IN THE MOUNTAINS.
PERIODS OF HEAVY RAIN ARE LIKELY. OF PARTICULAR CONCERN ARE THE
SOUTH AND SOUTHWEST FACING SLOPES OF THE SAN BERNARDINO MOUNTAINS
WHERE MOIST...SOUTH WINDS AROUND 50 MPH SEVERAL THOUSAND FEET ABOVE
SEA LEVEL...ARE EXPECTED TO FORCE STRONG OROGRAPHIC LIFTING. THIS
WILL LIKELY ENHANCE RAINFALL TOTALS WITH AS MUCH AS ONE FOOT OF RAIN
POSSIBLE LOCALLY. CONSIDERABLY LESS IS EXPECTED ON WEST FACING
SLOPES IN THE MOUNTAIN AREAS OF RIVERSIDE AND SAN DIEGO COUNTIES.
THIS WILL BE A LONG DURATION RAINFALL EVENT. AS HILLSIDES AND SLOPES
BECOME SATURATED...BURSTS OF HIGH RAIN INTENSITIES AND ISOLATED
THUNDERSTORMS COULD RESULT IN FLASH FLOODING AND MUDSLIDES. AREAS IN
AND BELOW RECENTLY BURNED AREAS WILL BE PARTICULARLY VULNERABLE.

BASED ON EXPECTED RAINFALL...THE SAN DIEGO AND SAN LUIS REY RIVERS
MAY DEVELOP SUBSTANTIAL FLOWS. ALL INTERESTS ALONG THE RIVER SHOULD
MONITOR LATER FORECASTS FOR POSSIBLE STATEMENTS OR WARNINGS.

THE SNOW LEVEL WILL MOSTLY BE ABOVE 6000 FEET UNTIL LATE IN THE
STORM. SIGNIFICANT SNOWFALL IS POSSIBLE AT AND ABOVE 7000 FEET WHERE
MORE THAN A FOOT OF SNOW COULD FALL. HOWEVER...THE AMOUNT OF WARM
AIR MOVING INTO THE STORM FROM THE SOUTH WILL STRONGLY AFFECT THE
SNOW LEVEL...SO THE SNOW LEVEL COULD POTENTIALLY BE ABOVE THE
RESORTS. VERY STRONG AND GUSTY SOUTH AND SOUTHWEST WINDS WILL BE
POSSIBLE AT TIMES OVER THE MOUNTAINS AND DESERTS...AND FOR A SHORTER
PERIOD OF TIME ALONG THE COAST.

A FLASH FLOOD WATCH MEANS THAT FLASH FLOODING WILL BE POSSIBLE BUT
IS NOT IMMINENT. PEOPLE IN THE WATCH AREA SHOULD CHECK PREPAREDNESS
AND STAY INFORMED ON THIS DEVELOPING STORM.

$$

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EDIS-12-26-04 1915 PST