Flash Flood Warning 11, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1100 AM PST SAT FEB 6 2010

NEW AVIATION DISCUSSION

.SYNOPSIS...

A STORM SYSTEM WILL BRING ADDITIONAL RAIN AND SNOW TO THE AREA
THROUGH THIS EVENING WITH A SLIGHT CHANCE OF THUNDERSTORMS. FOR
SUNDAY AND MONDAY...DRY AND WARMER CONDITIONS ARE EXPECTED. FOR
TUESDAY THROUGH THE END OF THE WEEK...THE PATTERN WILL BECOME
UNSETTLED YET AGAIN WITH SOME CHANCE OF PRECIP TUESDAY THROUGH
FRIDAY.

&&

.SHORT TERM (TODAY-MON)...MOISTURE MOVING ASHORE OVER THE SLO AND
SANTA BARBARA WILL CONTINUE TO MOVE INTO MODERATELY UNSTABLE AIR
MASS OVER VENTURA AND LOS ANGELES COUNTY THIS MORNING. RAINRATES
WILL CONTINUE TO EXCEED USGS DEBRIS FLOW THRESHOLDS THROUGH THE
REMAINDER OF THE MORNING AND VERY LIKELY CONTINUE THROUGH THE
AFTERNOON. THE BULK OF THE MOISTURE OVER SLO AND SANTA BARBARA
COUNTIES WILL MOVE EAST AND LIKELY EXIT LOS ANGELES COUNTY EARLY
THIS EVENING.

EXCERPT FROM PREVIOUS SHIFT...

BY SUNDAY...THE SHOWER ACTIVITY SHOULD BE CONFINED TO THE MOUNTAINS
AND INTERIOR SECTIONS OF SLO/SBA COUNTIES AS NORTHERLY FLOW SETS
UP ACROSS THE AREA. THE NORTHERLY FLOW THAT DEVELOPS COULD REACH
ADVISORY LEVELS ACROSS THE MOUNTAINS (ESPECIALLY THE I-5 CORRIDOR
AND THE SANTA YNEZ RANGE). WITH LESS CLOUD COVER AND NORTHERLY FLOW
TEMPS ON SUNDAY WILL BUMP UP A COUPLE OF DEGREES.

ON MONDAY...DRY CONDITIONS WILL CONTINUE ACROSS THE AREA AS A WEAK
UPPER RIDGE MOVES OVER THE AREA. WITH THE RIDGE OVERHEAD...WILL
EXPECT A CONTINUED WARMING TREND ACROSS THE AREA WITH MOST COASTAL
AND VALLEY AREAS IN THE LOWER TO MID 60S.

.LONG TERM (TUE-FRI)...FOR EXTENDED...CONFIDENCE IS LOW THROUGH
THE ENTIRE PERIOD AS MODEL SOLUTIONS ARE NOT IN GOOD AGREEMENT.

FOR TUESDAY/WEDNESDAY...MODELS HAVE THE SAME GENERAL IDEA WITH AN
UPPER LOW DROPPING SOUTH ACROSS CALIFORNIA. HOWEVER...SOME SOLUTIONS
HAVE A LAND TRAJECTORY WHILE OTHERS KEEP THE LOW FURTHER OVER THE
WATER. THIS UNCERTAINTY WILL GREATLY AFFECT THE RAINFALL POTENTIAL
FOR THE AREA. GIVEN THE UNCERTAINTY...WILL KEEP CHANCE POPS FOR
THE AREA ON TUESDAY...THEN SLIGHT CHANCE ON TUESDAY NIGHT...WITH
ONLY NORTH-SLOPE SHOWERS ON WEDNESDAY. HOPEFULLY...FUTURE MODEL
RUNS WILL HANDLE THE UPPER LOW BETTER.

FOR THURSDAY/FRIDAY...MODEL DISCREPANCIES GROW EVEN LARGER. OVERALL
THE PERIOD WILL BE UNSETTLED BUT EXACT TIMING AND LOCATION OF PRECIP
IS STILL MUCH IN QUESTION. FOR MY FORECAST...WILL LEAN FORECAST
TOWARDS THE GFS/CANADIAN SOLUTION WHICH WOULD MEAN A CHANCE OF PRECIP
OVER SLO/SBA COUNTIES ON THURSDAY...THEN SOME SLIGHT PRECIP CHANCES
FOR ALL AREAS ON FRIDAY. GIVEN THE MODEL UNCERTAINTIES...THIS
FORECAST WILL LIKELY CHANGE FROM ONE DAY TO THE NEXT.

&&

.AVIATION...06/1900Z.
LOW CONFIDENCE IN WIND DIRECTION THIS AFTERNOON AS SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS CAN CAUSE GUSTY SHIFTING WINDS. THE
LATEST MODEL DATA INDICATES THAT THE PREDOMINATE WIND DIRECTION WILL
FLUCTUATE BETWEEN SOUTH AND WEST WITH FURTHER VARIATIONS DUE TO
NEARBY SHOWER AND THUNDERSTORM ACTIVITY. BETTER CONFIDENCE IN
CONTINUED SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS...EXTENDING
WELL INTO THE LATE AFTERNOON SOUTH OF POINT CONCEPTION. DUE TO THE
SHOWERY NATURE OF THE PRECIPITATION...CONDITIONS CAN VARY FROM VFR
TO IFR IN A SHORT PERIOD OF TIME. SIMILAR CONDITIONS WILL PERSIST
SOUTH OF POINT CONCEPTION INTO THE EVENING...FOLLOWED BY IMPROVING
WEATHER AFTER MIDNIGHT.

KLAX AND KBUR...LOW CONFIDENCE IN WIND DIRECTION THIS AFTERNOON DUE
TO THE PRESENCE OF SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...HOWEVER THE PREDOMINANT WIND DIRECTION AT KLAX IS
NOW EXPECTED TO BE SOUTHWEST BASED ON THE LATEST MODEL DATA. THE
WIND DIRECTION AT KBUR WILL CONTINUE TO BE SOUTHEAST FOR THE NEXT
FEW HOURS...HOWEVER A WIND SHIFT TO SOUTHWEST IS POSSIBLE LATER THIS
AFTERNOON. THE SHOWERY NATURE OF THE PRECIPITATION WILL YIELD
RAPIDLY CHANGING CONDITIONS FROM VFR TO IFR. CONDITIONS WILL
IMPROVE LATER TONIGHT.

...NOTE...
THE ASOS EQUIPMENT AT KBUR...KVNY...KHHR...KCMA...AND KOXR HAS A
SOFTWARE ERROR THAT MAY LEAD TO INCORRECT CLOUD HEIGHTS WHEN THERE
ARE TWO OR MORE CLOUD LAYERS PRESENT. OBSERVATIONS AT KBUR WILL BE
QUALITY CONTROLLED 24 HOURS A DAY...OBSERVATIONS AT KVNY WILL BE
QUALITY CONTROLLED FROM 13Z-07Z...OBSERVATIONS AT KOXR WILL BE
QUALITY CONTROLLED FROM 15Z-05Z. TAFS FOR KVNY AND KOXR WILL NOT BE
AMENDED FOR CIGS DURING THE TIME THE OBSERVATIONS ARE NOT MONITORED
AND THERE ARE TWO OR MORE CLOUD LAYERS PRESENT.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
FLOOD WATCH (SEE LAXFFALOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

PUBLIC...THOMPSON/30
AVIATION...SWEET
SYNOPSIS...MEIER

WWW.WEATHER.GOV/LOSANGELES

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OXNARD CA
718 AM PST SAT FEB 06 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0345 AM     FLASH FLOOD      5 NW PASADENA           34.21N 118.20W
02/06/2010                   LOS ANGELES        CA   BROADCAST MEDIA

            MAJOR DEBRIS FLOW REPORTED NEAR CASTLE ROAD AT ESCALANTE
            DRIVE. HOME BURIED IN MUD UP TO THE WINDOWS...WITH 2
            PEOPLE TRAPPED INSIDE. NO INJURIES.

0345 AM     FLASH FLOOD      5 NW PASADENA           34.21N 118.20W
02/06/2010                   LOS ANGELES        CA   BROADCAST MEDIA

            MUD AND DEBRIS FLOW REPORTED AT OCEANVIEW BLVD AND
            FOOTHILL BLVD...APPROXIMATELY 2 MILES DOWN THE ROAD FROM
            THE STATION BURN AREA. REPORTS OF K-RAIL AND CARS MOVED
            DOWN ROAD BY DEBRIS FLOW...WITH KNEE-DEEP DEBRIS IN SOME
            PLACES.

&&

MEIER