FXUS66 KLOX 260412
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
815 PM PST FRI DEC 25 2009
.SYNOPSIS...
A WEAK UPPER LEVEL RIDGE WILL CONTINUE TO KEEP CONDITIONS DRY ACROSS
THE AREA THROUGH SATURDAY EVENING. A SERIES OF WEAK STORM SYSTEMS
MOVING THROUGH THE EASTERN PACIFIC WILL BRING A SLIGHT CHANCE OF
RAIN TO PARTS OF THE REGION SATURDAY NIGHT THROUGH MONDAY...THEN DRY
AND SEASONABLY COOL WEATHER IS EXPECTED TUESDAY THROUGH THURSDAY.
&&
.SHORT TERM (TONIGHT-MON)...LOW CLOUDS WERE STARTING TO DEVELOP OVER
PORTIONS OF THE SWRN CA COASTAL WATERS THIS EVENING...AND WERE
SPREADING INTO THE OUTER COASTAL WATERS OUT AHEAD OF AN APPROACHING
COLD FRONT. SOME LOW CLOUDS WERE ALSO DEVELOPING OVER THE SBA COUNTY
CENTRAL COAST AS WELL. LOW CLOUDS SHOULD EXPAND SOME ALONG THE
CENTRAL COAST OVERNIGHT...WITH PATCHY LOW CLOUDS MOVING INTO THE
L.A. COUNTY COAST LATER TONIGHT. THERE SHOULD ALSO BE INCREASING
HIGH CLOUDS MAINLY OVER SLO/SBA COUNTIES LATER TONIGHT. OTHERWISE
MOST OF THE REGION SHOULD HAVE MOSTLY CLEAR SKIES THRU THE NIGHT.
AN UPPER LEVEL TROUGH IS FORECAST TO MOVE INTO CENTRAL AND SRN CA ON
SAT...WITH WEAK UPPER LEVEL RIDGING EXPECTED ON SUN IN RESPONSE TO
AN APPROACHING UPPER LEVEL LOW OVER THE E PAC. A WEAKENING COLD
FRONT ASSOCIATED WITH THE UPPER TROF SAT WILL MOVE INTO SLO/SBA
COUNTIES SAT EVENING WITH A SLIGHT CHANCE OF SHOWERS. THE LATEST WRF
IS INDICATING A SLIGHT CHANCE OF SHOWERS MAY LINGER INTO SUN MAINLY
OVER SLO/SBA COUNTIES AS ADDITIONAL LOW LEVEL MOISTURE MOVES IN.
CURRENT CHANCE POPS OF 25-30 PERCENT ON SUN OVER SLO/SBA COUNTIES
MAY NEED TO BE LOWERED TO 20 PERCENT OR LESS. WILL LET MID SHIFT
TAKE A CLOSER LOOK AT THIS AS ADDITIONAL MODEL RUNS COME IN. AT ANY
RATE THERE WILL BE VARYING AMOUNTS OF CLOUDINESS OVER THE DISTRICT
THRU THE WEEKEND. TEMPS SHOULD TURN COOLER AND SLIGHTLY BELOW NORMAL
SAT AND ABOUT 4-8 DEG COOLER THAN SEASONAL NORMS ON SUN.
IT IS LOOKING MORE AND MORE LIKE THE UPPER LOW OFF THE COAST SUN
WILL SLIDE SE TOWARD NORTHERN BAJA SUN NIGHT AND MON...WITH THE
MOISTURE FROM THE SYSTEM REMAINING OFF THE COAST FOR THE MOST PART.
IN ADDITION...A SURFACE LOW ASSOCIATED WITH THE UPPER LOW WILL
INDUCE A BROAD E TO SE LOW LEVEL FLOW OVER THE DISTRICT WHICH WILL
BE GENERALLY OFFSHORE AT LEAST LATER SUN NIGHT AND MON MORNING...
FURTHER HAMPERING PRECIP FROM DEVELOPING OVER ANY PART OF THE
FORECAST AREA. WRF CROSS SECTIONS ALONG THE COAST SHOW DECENT
AMOUNTS OF MOISTURE MOVING INTO THE AREA ABOVE 800 MB ON MON...WITH
DRY CONDITIONS BELOW 850 MB...NOT A RECIPE FOR MUCH IN THE WAY OF
PRECIP. CURRENT FORECAST OF A SLIGHT CHANCE OF RAIN SUN NIGHT INTO
MON OVER MUCH OF THE DISTRICT MAINLY W OF THE HIGHEST MTNS LOOKS
SOMEWHAT REASONABLE...BUT THE BEST CHANCES OF PRECIP IS PROBABLY
CLOSER TO THE COAST AND OFF THE COAST. PARTLY TO MOSTLY CLOUDY SKIES
SHOULD STILL COVER THE AREA SUN NIGHT AND MON...WITH TEMPS EXPECTED
TO BE A COUPLE DEGREES BELOW NORMAL.
...FROM PREVIOUS DISCUSSION...
.LONG TERM (TUE-FRI)...A NWLY FLOW PATTERN ALOFT WILL SET UP OVER
THE FCST AREA TUE THRU THU...WITH DRY WEATHER EXPECTED...AND TEMPS
SLIGHTLY BELOW NORMAL. A WEAK TROF PASSES THROUGH NORTHERN CA ON WED
BUT EFFECTS ON OUR AREA WILL LIKELY JUST BE CLOUDS. PRESENTLY A NICE
BROAD UPPER RIDGE IS FORECAST FOR NEW YEARS DAY LEADING TO PLENTY OF
SUNSHINE AND AT OR SLIGHTLY ABOVE NORMAL TEMPS TO START THE NEW
YEAR.
&&
.AVIATION...25/2340Z...THERE IS A 30 PERCENT CHANCE KSMX...AND A 20
PERCENT CHANCE KLAX AND KLGB MAY NOT HAVE LOW CLOUDS AND MVFR
CONDITIONS LATE TONIGHT AND SAT MORNING. OTHERWISE...THERE IS
GENERALLY HI CONFIDENCE IN THE CURRENT TAF PACKAGE.
KLAX...THERE IS A 20 PERCENT CHANCE LOW CLOUDS AND MVFR CONDITIONS
MAY NOT AFFECT THE AIRFIELD LATE TONIGHT INTO SAT MORNING...
OTHERWISE GENERALLY HI CONFIDENCE IN THE CURRENT TAF.
KBUR...HI CONFIDENCE IN THE CURRENT TAF.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
PUBLIC...SIRARD/TRM
AVIATION...SIRARD
SYNOPSIS...TRM
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