Flash Flood Warning 11, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
300 AM PST WED NOV 12 2003

.SHORT TERM...UPPER LOW WAS CENTERED NEAR 32N/121W EARLY THIS
MORNING...ABOUT 200 MILES WEST SOUTHWEST OF LOS ANGELES...AND
WAS DRIFTING SLOWLY TO THE ENE. SATELLITE IMAGERY INDICATED
PLENTY OF DEEP MOISTURE BEING DRAWN NWD INTO THE FCST AREA...
AND SSMI PW VALUES WERE BETWEEN 1.2 AND 1.3 INCHES OFF THE EXTEMEE
SRN CA CST. A NICE UPPER LVL DIFFLUENT PATTERN ON THE NERN SIDE OF THE
UPPER LOW HAS SPREAD INTO THE AREA...AND WITH THE ASSISTANCE OF
THE FAVORED LEFT FRONT QUAD OF A 120 KNOT JET...NUMEROUS SHOWERS
AND THUNDERSTORM HAVE DEVELOPED ACRS THE AREA...MAINLY S OF PT
CONCEPTION. SOME HEAVY SHOWERS...WITH RADAR RAINFALL ESTIMATES
OF 0.7 INCHES PER HOUR TRAINED OVER THE RECENTLY BURNED AREAS IN
ERN VENTURA COUNTY BETWEEN MIDNIGHT AND 100 AM. DUE TO THE
SHARPLY INCREASED SENSITIVITY OF THE NOW BARE HILLSIDES TO HEAVY
RAIN...AND THE THREAT OF ADDITIONAL HEAVY SHOWERS AND POSSIBLY
TSTMS ACRS THE AREA TODAY...A FLASH FLOOD WATCH HAS BEEN ISSUED FOR
THE BURNED AREAS...AND LOCATIONS IMMEDIATELY ADJACENT TO THEM
UNTIL 900 PM THIS EVENING. IN THE WATCH AREA...THERE WILL BE THE
THREAT OF DAMAGING AND DANGEROUS MUD AND DEBRIS FLOWS DUE TO
HEAVY SHOWERS.

THE UPPER LOW IS PROGGED TO DRIFT RIGHT ACRS SOUTHERN LOS ANGELES
COUNTY LATE THIS AFTERNOON AND THIS EVENING. COOLING ALOFT ASSOCIATED
WITH THE CENTER OF THE UPPER LOW SHOULD INCREASE INSTABILITY ENOUGH
TO OFFSET THE FACT THAT THE BEST DYNAMICS SHOULD SHIFT TO THE N AND E
OF THE AREA LATER TODAY. THEREFORE...EXPECT PLENTY OF SHOWER AND
THUNDERSTORM ACTIVITY ACRS THE AREA THROUGH THIS EVENING...AT LEAST
FROM SOUTHERN SANTA BARBARA COUNTY SOUTH AND EAST. SOME OF THE
SHOWERS...AS MENTIONED...COULD BE QUITE HEAVY...AND MAY CAUSE SOME
LOCAL FLOODING OF ROADWAYS. AS THE AIR DESTABILIZES...AND COOLING ALOFT
OCCURS...THERE WILL BE A CHANCE OF SOME SMALL HAIL WITH SOME OF
THUNDERSTORMS TODAY AND EARLY TONIGHT. DO NOT EXPECT RAIN TO OCCUR
UNINTERRUPTED ALL DAY...AND THERE SHOULD BE SOME DRY PERIODS AND
POSSIBLY EVEN SOME SUNSHINE FROM TIME TO TIME...ESPECIALLY IN CSTL
AREAS. WITH LESS IN THE WAY OF DEEP MOISTURE ACRS SLO AND NRN SBA
COUNTIES...ALONG WITH DOWNSLOPING ELY FLOW...XPCT LESS IN THE WAY
OF SHOWERS/TSTMS...BUT EVEN THERE...SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE EXPECTED TODAY.

THE SHOWERY NATURE OF THE PRECIPITATION WILL LIKELY LEAD TO HIGHLY
VARIABLE RAINFALL TOTALS FROM LOCATION TO LOCATION TODAY. ANY AREA
THAT RECEIVES A HEAVY THNUNDERSTORM COULD ADD A QUICK HALF INCH OR
MORE OF RAIN TO THEIR STORM TOTAL IN LESS THAN AN HOUR. FURTHER
COMPLICATING THINGS IS THAT E TO NELY FLOW MAY REDUCE RAINFALL
TOTALS NEAR THE COAST AS DOWNSLOPING CAUSES SOME DRYING OF THE
RAIN. HOWEVER...ON AVERAGE EXPECT BETWEEN ONE THIRD OF AN INCH
AND TWO THIRDS OF AN INCH OF PRECIP ACRS L.A....VTU AND THE
MTNS AND S CST OF SBA COUNTIES...WITH LOCAL TOTALS IN EXCESS
OF 2 INCHES QUITE POSSIBLE.

SNOW LEVELS WILL START OUT RATHER HIGH TODAY...GENERALLY ABOVE
7500 FEET...BUT ARE EXPECTED TO LOWER TO 6500 FEET LATER TODAY
AND TONIGHT AS THE UPPER LOW MOVES ACROSS THE AREA. HOWEVER...
SOME LOW LVL DRY AIR PUSHING SWWD ACRS THE DESRTS SHOULD ALLOW
FOR SOME ADDITIONAL COOLING ON THE NORTHERN SIDE OF THE MTNS...
SO EXPECT SNOW LEVELS TO BE LOWER ON THE NORTHERN SIDE...
GENERALLY DROPPING TO 5500 FEET LATER TODAY AND POSSIBLY DOWN
TO 5000 FEET TONIGHT. HAVE DECIDED TO ISSUE A WINTER WEATHER
ADVISORY FOR THE NORTHERN MTNS OF VTU AND LOS ANGELES COUNTIES
FOR LATER TODAY AND TONIGHT...SINCE THERE SHOULD BE ENOUGH
WRAP AROUND MOISTURE PILING INTO THOSE AREAS ONCE SNOW LEVELS
LOWER TO ALLOW FOR GENERAL SNOW ACCUMULATIONS OF 4 TO 8 INCHES
ABOVE 5500 FEET. ELSEWHERE IN THE MTNS...ACCUMULATIONS SHOULD
AVERAGE 2 TO 4 INCHES ABOVE 6000 OR 6500 FEET. STRONG E TO NELY
WINDS WILL AFFECT THE MTNS THROUGH TONIGHT...CAUSING SOME BLOWING
AND DRIFTING SNOW AND REDUCED VISIBILITIES.

THE MODELS INDICATE THAT THE UPR LOW WILL PULL TO THE E OF THE
FCST AREA LATE TONIGHT. SHOWERS/TSTM SHOULD END ACROSS SBA COUNTY
AND MOST OF VTU COUNTY BY MIDNIGHT...AND ACRS L.A. COUNTY OVERNIGHT.
THE XCPTN WILL BE ACRS THE MTNS OF L.A./VTU COUNTIES...AND THE
ANTELOPE VLY...WHERE WRAP AROUND MOISTURE SHOULD KEEP THE THREAT
OF SHOWERS INTO EARLY THU MORNING.

XPCT DRYING ACRS THE AREA DURG THU...ALONG WITH INCREASED SUNSHINE.
TEMPS SHOULD BE UP A FEW DEGS IN MOST AREAS THU...ESPECIALLY ACRS
L.A. AND VTU COUNTIES. FLAT RIDGE ACRS THE ERN PAC WILL BE REPLACED
BY A BROAD TROUGH ON FRI...BUT OVERALL...SEE LTL CHANGE IN TEMPS
FOR FRI.

.LONG TERM...MODELS HAVE BACKED OFF FROM DIGGING THE TROUGH
SO SHARPLY ACRS CA OVER THE WEEKEND...SO HAVE REMOVED ANY
SHOWERS FROM THE FCST AND WL JUST GO WITH PTLY CLDY SAT AND
SUN. SOME WARMING SHOULD TAKE PLACE ACRS THE AREA
MON AND TUE AS RIDGING BUILDS INTO THE WEST COAST.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH (SEE LAXFFALOX).
WINTER WEATHER ADVISORY (SEE LAXWSWLOX).

&&

BRUNO

CAZ034>041-044>047-051>054-059-087-088-120200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
600 AM PST TUE NOV 11 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... TODAY

THERE WILL BE LOCAL GUSTY WINDS TO 35 MPH THIS MORNING IN THE
MOUNTAINS. THE AIRMASS IS STILL FAIRLY MOIST FROM THE RAIN SUNDAY
AND HUMIDITIES SHOULD STAY ABOVE 25%. TONIGHT A CHANCE OF RAIN WILL
DEVELOP...MOSTLY OVER LOS ANGELES AND VENTURA COUNTIES. RAINFALL
AMOUNTS WILL BE LIGHT. TOWARDS SUNRISE A SLIGHT CHANCE OF A
THUNDERSTORM WILL DEVELOP

.DAYS TWO THROUGH SEVEN... WEDNESDAY THROUGH MONDAY

WEDNESDAY WILL HAVE A CHANCE OF RAIN AND A SLIGHT CHANCE OF
THUNDERSTORMS THROUGH THE DAY. THE RAIN WILL MOSTLY BE FOCUSED SOUTH
OF POINT CONCEPTION AND THE MOUNTAINS WILL STAND THE BEST CHANCE OF
SEE THE THUNDERSTORMS. LIGHTNING WILL OCCUR WITH RAIN. RAINFALL
AMOUNTS SHOULD BE LESS THAN A QUARTER INCH...EXCEPT UNDER
THUNDERSTORMS. THE CHANCE OF RAIN AND THUNDERSTORMS WILL LAST INTO
THE EVEN AND SHOULD END BY MIDNIGHT.

HAZARDOUS WEATHER IS NOT FORECAST THURSDAY THROUGH MONDAY.

RORKE