Flash Flood Warning 10, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
315 PM PST THU JAN 24 2008

.SHORT TERM (TODAY-SUN)...WET PATTERN CONTINUES FOR THE AREA THROUGH
SUNDAY. A SMALL BUT PRETTY POTENT SYSTEM IS MOVING RAPIDLY THROUGH
THE AREA TODAY. MODERATE TO HEAVY RAIN HAS BEEN FALLING ALONG THE
CENTRAL COAST WITH SNOW LEVELS AROUND 3000 FT. THE BACK EDGE OF THE
RAIN IS QUICKLY APPROACHING THE CENTRAL COAST AND PRECIP SHOULD BE
TAPERING OFF THERE BY 4 PM. BEHIND THAT EXPECT JUST SCATTERED
SHOWERS AND PARTLY CLOUDY SKIES OVERNIGHT.

THIS SYSTEM WILL BRING WIDESPREAD RAIN TO VENTURA AND LA COUNTIES
LATER THIS AFTERNOON THROUGH THE EARLY EVENING HOURS, BUT AT ITS
CURRENT SPEED MOST OF THE RAIN SHOULD BE TAPERING OFF BY 9 PM, IF
NOT SOONER. RAIN AMOUNTS WITH THIS SYSTEM SHOULD RANGE FROM A HALF
INCH TO AN INCH, WITH UP TO 2 INCHES POSSIBLE IN THE FOOTHILLS AND
MOUNTAINS. HOWEVER, MODELS MAINTAIN A MOIST SOUTHERLY FLOW OF AIR
THROUGH FRIDAY AS WARM ADVECTION PROCESSES START TO TAKE OVER, SO
EVEN THOUGH THERE ARENT ANY ORGANIZED SYSTEMS MOVING THROUGH THE
AREA AFTER THIS EVENING, SHOWERS ARE EXPECTED TO CONTINUE OFF AND
ON, ESPECIALLY OVER HIGHER TERRAIN.

THE NEXT SYSTEM AND THE NEXT REAL PERIOD OF FOCUS IS EXPECTED TO
ARRIVE SAT NIGHT AND EARLY SUNDAY. MOST OF THE MODELS HAVE BEEN
PRETTY CONSISTENT WITH THE TIMING, THOUGH THE ECMWF CONTINUES TO BE
MORE PROGRESSIVE. GOING WITH THE CONSENSUS SOLUTION, THE UPPER LOW
IS EXPECTED TO DROP SOUTH TO A POSITION NEAR 33N/130W SAT AFTERNOON.
A BUILDING SHORTWAVE RIDGE AHEAD OF THE LOW WILL PUMP WARM AIR INTO
THE AREA FRIDAY AND SATURDAY, RAISING SNOW LEVELS SIGNIFICANTLY.
MOST MODELS KEEP THE AREA PRETTY DRY LATE FRI AND SAT WITH THE
EXCEPTION OF THE CENTRAL COAST AND SOUTH FACING MOUNTAIN SLOPES
WHERE SCATTERED SHOWERS WILL CONTINUE THROUGH THE PERIOD WITH MOSTLY
LIGHT RAIN AMOUNTS. HOWEVER, BY SAT NIGHT, A DEEP PLUME OF
SUBTROPICAL MOISTURE WILL ORIENT ITSELF RIGHT OVER THE AREA WITH
VERY IMPRESSIVE SOUTHERLY WINDS UP TO 50 KT AT 975 MB. WITH PWS
NEAR 1.4 INCHES STRONG OROGRAPHICS AND A FAVORABLE JET PATTERN, ALL
THE FACTORS WILL BE IN PLACE FOR A SIGNIFICANT RAIN EVENT WITH THE
POTENTIAL FOR SUBSTANTIAL HYDRO ISSUES. WILL BE ISSUING A HYDROLOGIC
OUTLOOK PRODUCT (LAXESFLOX) SHORTLY TO HIGHLIGHT THE ISSUES FOR SAT
NIGHT AND SUN. EVEN SOME OF THE LARGER STREAMS AND RIVERS MAY BE
APPROACHING MONITOR LEVEL WITH THIS EVENT CONSIDERING THE AMOUNT OF
RAIN WERE EXPECTING ON TOP OF WHAT WEVE ALREADY HAD. WINDS WILL
ALSO BE A BIG CONCERN AS A STRONG SOUTH GRADIENT SETS UP ACROSS THE
AREA.

RAIN AMOUNTS WITH THIS NEXT SYSTEM, ASSUMING ALL THE ABOVE FACTORS
ARRIVE AS PROJECTED SHOULD BE 2-5 INCHES COAST AND VALLEYS, 5-10
INCHES IN THE MOUNTAINS WITH ISOLATED LOCATIONS CLOSE TO 12 INCHES.
THE HIGHEST AMOUNTS WILL BE SOUTH OF PT CONCEPTION WHERE OROGRAPHICS
WILL BE THE BEST. SNOW LEVELS WILL BE RISING RAPIDLY FRI INTO
SATURDAY, AND BY THE TIME THE NEXT SIGNIFICANT BATCH OF PRECIP
ARRIVES SNOW LEVELS SHOULD BE ABOVE 6000 FEET, PERHAPS QUITE A BIT
ABOVE. HIGHER PEAKS COULD GET A FAIR AMOUNT OF SNOW BUT A VAST
MAJORITY OF THE MOUNTAIN AREAS WILL BE GETTING RAIN.

NOT REAL CONFIDENT ON THE TIMING OF THIS SYSTEM SINCE IT IS A CUTOFF
LOW AND MODELS DONT TYPICALLY HANDLE THESE TOO WELL. RAIN COULD
ARRIVE LATER AND STAY LONGER INTO SUNDAY, BUT FOR NOW THE BEST GUESS
IS THAT THE SATURDAY NIGHT THROUGH EARLY SUNDAY PERIOD WILL BE THE
HEAVIEST.

.LONG TERM...BY MONDAY...MODEL AGREEMENT IMPROVES. BOTH THE ECMWF
AND THE GFS HAVE THE TROUGH EXITING THE REGION ON MONDAY AND WEAK
RIDGING BUILDING OVER THE AREA LATE MONDAY AND EARLY TUESDAY. SO A
BREAK IN THE WEATHER IS EXPECTED NEXT WEEK. ON TUESDAY...BOTH MODELS
DEVELOP A TROUGH OFF THE PACNW...WITH THE GFS BEING DEEPER AND MORE
SIGNIFICANT. THIS TROUGH MOVES THROUGH THE REGION LATE TUESDAY ALONG
THE CENTRAL COAST AND SOUTH OF POINT CONCEPTION ON WEDNESDAY
BRINGING YET ANOTHER SHOT OF RAIN AND SNOW TO THE REGION.

&&

.AVIATION...24/2000Z

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE THE ORDER OF
THE DAY AS COLD UNSTABLE AIR CONTINUES ACROSS THE ENTIRE DISTRICT.
THE CEILING AND VISIBILITY WILL CHANGE QUICKLY AND OFTEN AS THESE
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS MOVE THROUGH THE
DISTRICT. THE SURFACE WINDS MAY BECOME ERRATIC NEAR ANY OF THE
HEAVIER SHOWERS AND THUNDERSTORMS.

KLAX AND KBUR...SHOWERS AND ISOLATED THUNDERSTORMS WILL AFFECT THE
TAF SITES THROUGH THE DAY WITH QUICKLY CHANGING CEILINGS AND
VISIBILITY. ERRATIC WINDS MAY ALSO COMPLICATE THE PICTURE NEAR ANY
OF THE HEAVIER SHOWERS AND THUNDERSTORMS. A LOW CONFIDENCE FORECAST.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
FLOOD WATCH (SEE LAXFFALOX).
SNOW ADVISORY (SEE LAXWSWLOX).
SMALL CRAFT ADVISORY (SEE LAXCWFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

PUBLIC...DANIELSON/WOFFORD
AVIATION...SWEET

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
600 PM PST THU JAN 24 2008

CAZ034>041-044>047-051>054-059-087-088-251400-
SAN LUIS OBISPO COUNTY CENTRAL COAST-
SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY-
SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY-
SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST-
LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES-
VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS-
SANTA MONICA MOUNTAINS RECREATIONAL AREA-
LOS ANGELES COUNTY VALLEYS-SAN LUIS OBISPO COUNTY MOUNTAINS-
SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS-
LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE-
ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY-
600 PM PST THU JAN 24 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... TODAY
A SERIES OF PACIFIC STORMS WILL CONTINUE TO AFFECT THE REGION
THROUGH THE WEEKEND. THE LATEST SYSTEM CURRENTLY MOVING THROUGH THE
AREA WILL CONTINUE TO PRODUCE LOCALLY HEAVY RAINFALL...SNOW IN THE
MOUNTAINS AND A NUMBER OF VALLEYS...AND ISOLATED THUNDERSTORMS WITH
GUSTY WINDS AND SMALL HAIL. FLASH FLOOD WATCHES FOR THE BURN AREAS
WILL BE IN EFFECT FOR SANTA BARBARA...VENTURA AND LOS ANGELES
COUNTIES TODAY. TRAVEL MAY BE VERY DANGEROUS WHERE SNOW OR HEAVY
RAIN FALLS THROUGH TONIGHT. ISOLATED THUNDERSTORMS WILL ALSO MAKE IT
HAZARDOUS OVER THE COASTAL WATERS WITH LIGHTNING AND WATERSPOUTS.
SHOWERS WILL CONTINUE TO THREATEN THE AREA THEREAFTER. IN
ADDITION...GALE FORCE WINDS WITH LOCALLY HEAVY SEAS WILL AFFECT THE
OUTER WATERS THROUGH THIS EVENING...THEN SPREAD INTO THE INNER
WATERS LATE TONIGHT.

* WINTER STORM WARNING.......SEE WWUS46 KLOX - WSWLOX FOR DETAILS *

* GALE WARNING...............SEE FZUS56 KLOX - CWFLOX FOR DETAILS *

* FLOOD WATCH................SEE WGUS66 KLOX - FFALOX FOR DETAILS *

* SNOW ADVISORY..............SEE WWUS46 KLOX - WSWLOX FOR DETAILS *

* WIND ADVISORY..............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* MARINE WEATHER STATEMENT...SEE FZUS76 KLOX - MWSLOX FOR DETAILS *

* SPECIAL WEATHER STATEMENT..SEE WWUS86 KLOX - SPSLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN... FRIDAY THROUGH WEDNESDAY

PERIODS OF RAIN WILL AFFECT THE AREA THROUGH SUNDAY. THERE IS THE
POTENTIAL FOR VERY HEAVY RAIN OVER SAN LUIS OBISPO AND NORTHERN
SANTA BARBARA COUNTIES FRIDAY AFTERNOON THROUGH THE NIGHT...THEN
OVER MOST OF THE AREA SATURDAY NIGHT INTO SUNDAY. PERIODS OF HEAVY
SNOW...AND A SLIGHT CHANCE OF THUNDERSTORMS WILL ALSO REMAIN THROUGH
SATURDAY. A FLASH FLOOD WATCH WILL REMAIN IN EFFECT FOR THE BURN
AREAS OF SANTA BARBARA...VENTURA AND LOS ANGELES COUNTIES THROUGH
FRIDAY. THIS WATCH WILL LIKELY NEED TO BE APPLIED TO SATURDAY NIGHT
AS WELL...AND MAY INCLUDE AREAS OTHER THAN THE BURN
AREAS...ESPECIALLY IN SANTA BARBARA COUNTY. IN ADDITION...STRONG AND
GUSTY WINDS WILL IMPACT THE AREA BEGINNING TONIGHT AND LASTING
THROUGH SUNDAY. WIND ADVISORIES AND GALE WARNINGS ARE IN PLACE TO
ACCOUNT FOR THE POTENTIALLY HAZARDOUS CONDITIONS CAUSED BY THESE
WINDS.

* WINTER STORM WARNING.......SEE WWUS46 KLOX - WSWLOX FOR DETAILS *

* GALE WARNING...............SEE FZUS56 KLOX - CWFLOX FOR DETAILS *

* FLOOD WATCH................SEE WGUS66 KLOX - FFALOX FOR DETAILS *

* WIND ADVISORY..............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* MARINE WEATHER STATEMENT...SEE FZUS76 KLOX - MWSLOX FOR DETAILS *

* SPECIAL WEATHER STATEMENT..SEE WWUS86 KLOX - SPSLOX FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

KITTELL