FXUS66 KLOX 120428
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
830 PM PST FRI DEC 11 2009
.SYNOPSIS...
SHOWERS WITH HIGH ELEVATION SNOW SHOWERS WILL CONTINUE ACROSS THE
AREA TONIGHT. ANOTHER MORE POTENT STORM SYSTEM WILL MOVE INTO THE
AREA SATURDAY AFTERNOON...BRINGING SIGNIFICANT RAIN AND HIGH
ELEVATION SNOW TO THE AREA THROUGH SUNDAY MORNING. DRY AND WARMING
CONDITIONS ARE EXPECTED NEXT WEEK.
&&
.SHORT TERM (TONIGHT-MON)...SCATTERED SHOWERS CONTINUED TO MOVE INTO
THE FORECAST AREA THIS EVENING AS A BROAD...MOIST WESTERLY FLOW
INTO THE REGION CONTINUED. RAINFALL RATES THIS EVENING HAVE BEEN
GENERALLY LESS THAN A TENTH OF AN INCH PER HOUR. SNOW LEVELS WERE
AROUND 6000 FT OR SO THIS EVENING WITH SNOW SHOWERS OVER THE HIGHER
ELEVATIONS. IT LOOKS LIKE PLENTY OF SHOWERS WILL PERSIST OVERNIGHT
AS THE OVERALL WEATHER PATTERN CHANGES LITTLE.
THE WESTERLY FLOW ALOFT WILL CONTINUE ON SAT...WITH ADDITIONAL
CHANCES OF SHOWERS OVER THE REGION THRU THE DAY. AN UPPER LEVEL TROF
IS FORECAST TO APPROACH CENTRAL CA ON SAT THEN MOVE INLAND SAT NIGHT
AS SUN. A POTENT COLD FRONT ASSOCIATED WITH THE UPPER TROF WILL MOVE
ASHORE OVER SLO/SBA COUNTIES BY LATE SAT THEN PUSH THRU THE
REMAINDER OF THE DISTRICT SAT NIGHT. RAIN AND MOUNTAIN SNOW WILL
BECOME WIDESPREAD OVER THE AREA BY SAT EVENING AND CONTINUE THRU THE
NIGHT BEFORE TAPERING TO SCATTERED SHOWERS SUN MORNING. THIS SYSTEM
WILL ALSO BE ACCOMPANIED WITH STRONG AND GUSTY S WINDS SAT AFTERNOON
AND SAT EVENING OVER MUCH OF THE REGION...ALTHO WINDS WILL BE
STRONGEST OVER HIGHER TERRAIN AND INTO THE ANTELOPE VALLEY. WIND
ADVISORIES MAY EVENTUALLY BE NEEDED FOR MANY AREAS DURING THE
PERIOD. THE WINDS WILL ALSO MAKE FOR GOOD OROGRAPHIC LIFT FOR
ENHANCED RAINFALL ON THE S SLOPES. IT LOOKS LIKE THE POTENTIAL
CONTINUES FOR RAINFALL FROM SATURDAY THRU SUN MORNING TO RANGE FROM
0.75 INCH TO 1.50 INCHES FOR THE COAST AND VALLEYS...AND 1.50 INCHES
TO 3.00 INCHES FOR THE FOOTHILLS AND MOUNTAINS BELOW THE SNOW LEVEL.
SNOW LEVELS ARE EXPECTED TO HOVER AROUND 6000 FEET...WITH
SIGNIFICANT ACCUMULATING SNOW POSSIBLE OVER THE HIGHER ELEVATIONS
FROM LATE SAT INTO SUN MORNING. WITH THE COMBINATION OF SNOWFALL AND
STRONG WINDS...HAZARDOUS WINTRY WEATHER CONDITIONS WILL BE
POSSIBLE...AND A WINTER STORM WATCH IS IN EFFECT FOR THE HIGHER
MOUNTAINS OF VENTURA AND LOS ANGELES COUNTIES. PLEASE SEE LAXWSWLOX
FOR THE LATEST INFO ON THE WINTER STORM WATCH. ALSO...PLEASE SEE THE
LATEST SPECIAL WEATHER STATEMENT (LAXSPSLOX) FOR FURTHER DETAILS ON
THE STORMY WEATHER OVER THE WEEKEND.
A SLIGHT CHANCE OF SHOWERS AND MOUNTAINS SNOW SHOWERS WILL PERSIST
SUN NIGHT AS THE UPPER TROF MOVES FURTHER INLAND. AN UPPER LEVEL
RIDGE IS EXPECTED TO BUILD INTO CENTRAL CA ON MON...WITH DRY AND
WARMER CONDITIONS EXPECTED ACROSS THE FORECAST AREA.
...FROM PREVIOUS DISCUSSION...
.LONG TERM (TUE-FRI)...OVERALL...12Z MODELS IN GOOD AGREEMENT WITH
THE EXTENDED FORECAST. AT UPPER LEVELS...FLAT RIDGE WILL DEVELOP
ON TUESDAY/WEDNESDAY THEN STRENGTHEN ON THURSDAY/FRIDAY. NEAR THE
SURFACE...VARYING DEGREES OF OFFSHORE FLOW SHOULD PERSIST.
FORECAST WISE...THE ABOVE PATTERN WILL RESULT IN DRY CONDITIONS
AND A WARMING TREND THROUGH THE PERIOD. WITH A MORE ZONAL FLOW
ON TUESDAY/WEDNESDAY...SOME MID/HIGH CLOUDS WILL LIKELY DRIFT
BY AND PRODUCE PARTLY CLOUDY CONDITIONS. THE OFFSHORE GRADIENTS
WILL ALSO PRODUCE SOME NORTHEAST CANYON WINDS DURING THE PERIOD.
&&
.AVIATION...12/0420Z...MODERATE TO HI CONFIDENCE IN THE CURRENT TAF
PACKAGE. LOW CLOUDS AND MVFR CIGS/VSBYS WILL BE LIKELY AT ALL
AIRFIELDS TONIGHT AND MUCH OF SAT...ALTHO THERE IS A 40 PERCENT
CHANCE OF IFR CONDITIONS AT TIMES WITH ANY HEAVIER SHOWERS...FOG AND
LOW STRATUS THROUGH EARLY SAT. THESE CONDITIONS WILL CONTINUE INTO
SAT NIGHT AS ANOTHER STORM SYSTEM MOVES INTO THE REGION.
KLAX AND KBUR...MODERATE TO HI CONFIDENCE IN THE TAFS. THERE IS A
30-40 PERCENT CHANCE OF IFR VSBYS/CIGS AT TIMES THROUGH EARLY SAT
AND AGAIN SAT NIGHT.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH (SEE LAXWSWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
&&
$$
PUBLIC...SIRARD/THOMPSON
AVIATION...SIRARD
SYNOPSIS...RAT
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