Area Forecast Discussion
Issued by NWS Los Angeles, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KLOX 260601 AAB
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
940 PM PST SUN JAN 25 2015

...AVIATION DISCUSSION UPDATED...

.SYNOPSIS...
TWO LOW PRESSURE SYSTEMS WILL IMPACT SOUTHWESTERN CALIFORNIA THIS
WEEK. THE FIRST SYSTEM WILL MOVE THROUGH THE REGION MONDAY AFTERNOON
THROUGH TUESDAY WITH CHANCES OF RAIN IN ALL AREAS. THE SECOND SYSTEM
IS EXPECTED THURSDAY NIGHT THROUGH SATURDAY MORNING WITH POSSIBLE
PRECIPITATION FOR THE VENTURA AND LOS ANGELES COUNTY MOUNTAINS AND
ANTELOPE VALLEY. OTHERWISE...VARYING AMOUNTS OF CLOUDS AND NEAR
SEASONAL TEMPERATURES CAN BE EXPECTED ACROSS SOUTHWESTERN CALIFORNIA
THROUGH THE WEEK.

&&

.SHORT TERM (TODAY-WED)...EVENING UPDATE...
WE SAW RECORD HEAT TODAY AT A FEW LOCATIONS INCLUDING OXNARD WITH A
HIGH OF 85 BREAKING THE OLD RECORD OF 84 BACK IN 1951 FOR THIS DATE.
ALSO SANTA BARBARA AP TIED THE OLD RECORD AT 79 DEGREES SET A FEW
YEARS BACK IN 2012 AND 1951. LASTLY PASO ROBLES REACHED 78 DEGREES
WHICH WAS A NEW RECORD BREAKING THE OLD RECORD OF 76 DEGREES SET IN
2014. AS FAR AS THE WINDS...THEY HAVE DROPPED OFF RAPIDLY EARLY THIS
EVENING. THE LAX-DAG WAS STILL WEAKLY OFFSHORE BUT TRENDING NEARLY
+4 MB OVER THE LAST 24 HOURS.

THERE WILL BE A MAJOR WEATHER PATTERN CHANGE OVER THE NEXT 24 HOURS
AS A FAIRLY EXPANSIVE UPPER LOW LOCATED AROUND 300 MILES WEST OF
BAJA WILL START TO ROTATE TO THE NORTH AS THE UPPER RIDGE GETS
PUSHED EASTWARD. AS USUAL...MODELS SEEM TO HAVE A TOUGH TIME
HANDLING MANY DETAILS WITH ANY WET SYSTEM MOVING IN FROM THE
SOUTHWEST. ALTHOUGH MOST ALL THE MODELS ARE IN PRETTY GOOD AGREEMENT
BRINGING STEADY LIGHT RAIN OVER THE AREA INITIALLY LATE MONDAY
AFTERNOON OR EARLY EVENING FROM THE SOUTH OVER LA COUNTY AND THEN
PIVOTING NORTH TOWARDS SLO COUNTY BY MONDAY NIGHT. THE BULK OF THE
RAIN WILL REMAIN ACROSS THE INTERIOR SECTIONS OF THE FORECAST AREA
WHILE COASTAL AREAS COULD SEE LESS THAN A TENTH OF AN INCH.

THE LATEST 00Z NAM CONCERNS ME A BIT IN RESPECT TO POSSIBLE ELEVATED
THUNDERSTORMS WITH THE CENTER OF THE LOW MOVING OVER THE COASTAL
WATERS MONDAY NIGHT INTO EARLY TUESDAY MORNING. 500 MB TEMPS LOWER
TO AROUND -22 DEGREES C AND THERE ARE A COUPLE OF RELATIVELY STRONG
VORT MAX`S MOVING OVER THE SO CAL BIGHT. ALSO...LIFTED INDEX VALUES
ARE MORE IMPRESSIVE THAN WOULD THINK WITH THIS UPPER LOW. HAVE RAN
SOME LOCAL FORECAST SOUNDINGS OVER THE SO CAL BIGHT AND COASTAL
AREAS AND EXCEPT FOR THE LACK OF LOW LEVEL MOISTURE...THERE IS SOME
ELEVATED INSTABILITY TO WORK WITH. AT THIS POINT WILL LEAVE QPF
ALONE AND LET THE MID SHIFT LOOK AT LOCAL HIGH RES MODELS TO PICK UP
ON SOME CONVECTIVE AREAS. ONE OTHER INTERESTING NOTE...THERE IS SOME
DECENT LOW LEVEL VEERING WINDS WITH THIS UPPER LOW. SO IF A FEW
STORMS DO DEVELOP OVER THE COASTAL WATERS...THE POSSIBILITY OF
ISOLATED WATERSPOUTS CAN`T BE RULED OUT MONDAY NIGHT INTO TUESDAY
MORNING.

IN RESPECT TO THE REST OF THE FORECAST...IT LOOKS TO BE IN GREAT
SHAPE FOR THE SHORT AND LONG TERM. AGAIN...WILL HAVE THE MID SHIFT
LOOK AT MORE HIGH RES DATA INCLUDING RAP AND HRRR INCLUDING THE
LOCAL 4KM WRF.

***FROM PREVIOUS DISCUSSION***

TONIGHT THROUGH MONDAY MORNING...THE UPPER LOW W OF BAJA WILL START
TO MOVE NW ALONG THE WESTERN FRINGE OF THE UPPER RIDGE...WHILE THE
UPPER RIDGE SHIFTS INTO THE WESTERN U.S. CLOUDS WILL CONTINUE TO
INCREASE ON MONDAY...ALONG WITH THE CHANCE OF SHOWERS AS THE UPPER
LOW STARTS TO MOVE NE TOWARDS SOCAL. POPS WERE INCREASED INTO THE
LIKELY CATEGORY FOR MOST OF LA COUNTY FOR THE MONDAY EVENING TIME
PERIOD...WHICH LOOKS LIKE THE BEST WINDOW FOR MEASURABLE RAIN. WITH
WEAK OFFSHORE FLOW AT THE SURFACE...THE ANTELOPE VALLEY AND THE
NORTH FACING SLOPES OF THE SAN GABRIEL MOUNTAINS WILL LIKELY HAVE
THE HIGHEST RAINFALL AMOUNTS. EXPECTING 0.25"-0.50" OF RAIN IN THESE
AREAS...WITH LIGHTER AMOUNTS W OF THE MOUNTAINS. ANY RAIN SHOWERS
SHOULD BE PRETTY MUCH DONE BY TUESDAY MORNING AS THE UPPER LOW
WEAKENS AND MOVES N. NOT MUCH SNOW EXPECTED WITH THIS SYSTEM...AS
SNOW LEVELS WILL GENERALLY REMAIN ABOVE 7000 FT...WITH LIGHT
ACCUMULATIONS POSSIBLE ABOVE THAT ALTITUDE. NO T-STORMS IN THE
FORECAST AS THEIR WILL BE LITTLE INSTABILITY TO WORK WITH (LESS THAN
500 J/KG OF CAPE OVER THE COASTAL WATERS) AND LIFT ASSOCIATED WITH
THE UPPER LOW WILL BE RELATIVELY WEAK. HOWEVER...WOULDN`T BE TOTALLY
SURPRISED IF THERE IS A T-STORM OR TWO WELL OFF THE COAST ON MONDAY
EVENING.

MAX TEMPS ON MONDAY AND TUESDAY WILL BE MUCH COOLER THAN THEY WERE
OVER THE WEEKEND...WITH NEAR NORMAL HIGHS EXPECTED. WEDNESDAY WILL
BE SEVERAL DEGREES WARMER AS A WEAK RIDGE POPS UP AHEAD OF THE NEXT
TROF OF LOW PRESSURE. WEAK OFFSHORE GRADIENTS AND FEWER CLOUDS WILL
HELP WITH THE WARMING ON WEDNESDAY AS WELL.

.LONG TERM (THU-SUN)...

LATEST MODELS ARE IN FAIRLY GOOD SYNOPTIC AGREEMENT THROUGH NEXT
WEEKEND...BUT WE WILL BE DEALING WITH ANOTHER CUTOFF LOW FRIDAY
THROUGH SUNDAY...SO WE`LL SEE HOW THAT GOES. CURRENT FORECAST HAS A
SLIGHT CHANCE OF SHOWERS FOR THE VENTURA/LA MOUNTAINS AND THE
ANTELOPE VALLEY THURSDAY THROUGH SATURDAY. FORECAST CONFIDENCE IS
RELATIVELY LOW...BUT NOT EXPECTING THIS TO BE A MAJOR RAIN PRODUCER
AT THIS TIME. CURRENT FORECAST ALSO HAS NEAR NORMAL TEMPS FOR
THURSDAY AND FRIDAY...WITH THE UPPER-LEVEL TROUGH OVERHEAD. SLIGHT
WARMING TREND FORECASTED FOR NEXT WEEKEND AS THE UPPER LOW DRIFTS TO
THE SE AND RIDGING/OFFSHORE FLOW DEVELOPS.

&&

.AVIATION...26/06Z...

AT 0520Z AT KLAX... THERE WAS NO INVERSION.

OVERALL...MODERATE CONFIDENCE IN 06Z TAFS.  REDUCED CONFIDENCE DUE
TO UNCERTAINTY IN THE TIMING AND INTENSITY OF THE INCOMING
PRECIPITATION AND THE EFFECT ON WIND FLOW AND VSBY.  AN INCREASING
CHANCE OF PRECIPITATION ACROSS THE REGION BEGINNING IN LOS ANGELES
COUNTY 22Z-00Z AND MOVING NORTH TOWARD SAN LUIS OBISPO COUNTY BY
06Z.  CONDITIONS ARE MOST LIKELY TO REMAIN VFR THROUGH THE FORECAST
PERIOD THOUGH THERE IS A THIRTY PERCENT CHANCE OF MVFR CONDITIONS
AFTER 23Z.

KLAX...MODERATE CONFIDENCE IN 06Z TAF.  REDUCED CONFIDENCE DUE TO
UNCERTAINTY IN THE TIMING AND INTENSITY OF THE INCOMING
PRECIPITATION AND THE EFFECT ON WIND FLOW AND VSBY.  AN INCREASING
CHANCE OF PRECIPITATION BEGINNING 22Z-00Z.  CONDITIONS ARE MOST
LIKELY TO REMAIN VFR THROUGH THE FORECAST PERIOD THOUGH THERE IS A
THIRTY PERCENT CHANCE OF MVFR CONDITIONS AFTER 23Z.  A THIRTY
PERCENT CHANCE OF SOUTHEAST TO EAST WINDS GREATER THAN 7 KTS 09Z-18Z.

KBUR...MODERATE CONFIDENCE IN 06Z TAF.  REDUCED CONFIDENCE DUE TO
UNCERTAINTY IN THE TIMING AND INTENSITY OF THE INCOMING
PRECIPITATION AND THE EFFECT ON WIND FLOW AND VSBY.  AN INCREASING
CHANCE OF PRECIPITATION BEGINNING 22Z-00Z.  CONDITIONS ARE MOST
LIKELY TO REMAIN VFR THROUGH THE FORECAST PERIOD THOUGH THERE IS A
THIRTY PERCENT CHANCE OF MVFR CONDITIONS AFTER 23Z.

.MARINE...25/745 PM...

AN AREA OF LOW PRESSURE OFF OF CENTRAL BAJA WILL MOVE NORTH OVER THE
AREA AND SOUTH AND SOUTHEAST WIND GUST TO AROUND 25 KT ARE EXPECTED
MONDAY MORNING AND PERSIST THROUGH THE AFTERNOON. THE STRONGEST
WINDS ARE EXPECTED OVER THE SANTA BARBARA CHANNEL AND SANTA MONICA
BASIN. OTHERWISE...THERE IS A CHANCE FOR SMALL CRAFT ADVISORY
CONDITIONS OVER THE OUTER WATERS THRU THRU FRI AS NORTH WINDS
DEVELOP AND THEN STRENGTHEN.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&
$$

PUBLIC...KAPLAN/SUKUP
AVIATION...KJ
MARINE...SIRARD
SYNOPSIS...SIRARD

WWW.WEATHER.GOV/LOSANGELES





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.