NWS Area Forecast Discussion

000
FXUS66 KLOX 111638
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
840 AM PST THU MAR 11 2010

.SYNOPSIS...
HIGH PRESSURE MAIN INFLUENCE FOR THE SOUTHLAND THROUGH FRIDAY WITH
SEASONABLE TEMPERATURES. A WEAK SYSTEM WILL BRING CHANCES OF RAIN TO
NORTHERN AREAS FRIDAY NIGHT AND SATURDAY...WITH COOLING EVERYWHERE.
STRONGER RIDGE BUILDS IN EARLY NEXT WEEK FOR WELL ABOVE SEASONAL
TEMPERATURES.

&&

.SHORT TERM (TODAY-SAT)...FORECAST IN GOOD SHAPE THIS MORNING. AS
WEAK OFFSHORE GRADS SETUP AND A RIDGE PUSHES IN FROM THE
SOUTHWEST...EXPECT A GOOD 10 DEGREES OF WARMING FROM YESTERDAY.
LIGHT NORTHEAST FLOW WILL STRENGTHEN SLIGHTLY THROUGH THE
MORNING...BUT LOOKS TO STAY BELOW ADVISORY STRENGTH.

***FROM PREVIOUS DISCUSSION***

FOR FRIDAY/SATURDAY...EXPECT A COOLING TREND AS THE TAIL END OF A
SYSTEM MOVES ACROSS THE AREA. AT THIS TIME...THE TAIL END OF THIS
FRONT WILL BEGIN TO MOVE ACROSS SLO COUNTY FRIDAY AFTERNOON...THEN
WILL SWEEP ACROSS THE REST OF THE AREA FRIDAY NIGHT. AT THIS TIME
THIS SYSTEM IS VERY WEAK WITH MEASURABLE RAIN ONLY EXPECTED ACROSS
SLO/SBA COUNTIES AND POSSIBLY THE VENTURA COUNTY MOUNTAINS. ANY RAIN
THAT DEVELOPS WILL BE ON THE LIGHT SIDE (GENERALLY LESS THAN ONE
QUARTER INCH) AND SHOULD CAUSE NO SIGNIFICANT PROBLEMS FOR THE AREA.
AS THE SYSTEM MOVES THROUGH...IT WILL BRING SOME COOLER AIR WITH
MOST AREAS SEVERAL DEGREES BELOW SEASONAL NORMS BY SATURDAY. BY
SATURDAY AFTERNOON/EVENING...EXPECT SOME NORTHERLY WINDS TO DEVELOP
IN THE WAKE OF THE FRONT WHICH COULD REACH ADVISORY LEVELS. THIS
WILL BE MONITORED CLOSELY.

.LONG TERM (SUN-WED)...FOR THE EXTENDED...MODELS ARE IN GOOD
SYNOPTIC AGREEMENT...WITH SOME FINE WEATHER EXPECTED EARLY NEXT
WEEK. AT UPPER LEVELS...RIDGE BUILDS OVER THE AREA ON SUNDAY...
THEN PEAKS IN STRENGTH MONDAY/TUESDAY...BEFORE WEAKENING ON
WEDNESDAY AS A WEAK TROUGH MUSCLES IN. NEAR THE SURFACE...SOME
DECENT OFFSHORE FLOW DEVELOPS SUNDAY THROUGH TUESDAY.

WITH THIS PATTERN...WILL EXPECT CLEAR AND DRY CONDITIONS THROUGH
THE PERIODS. TEMPS WILL SHOW A DRAMATIC WARMING TREND WITH MOST
AREAS WEST OF THE MOUNTAINS IN THE MID 70S TO MID 80S ON MONDAY
AND TUESDAY. A LITTLE BIT OF COOLING WILL OCCUR ON WEDNESDAY...
BUT TEMPS WILL STILL BE WELL ABOVE SEASONAL NORMS. WITH THE
OFFSHORE FLOW...THERE WILL BE SOME CANYON WINDS ACROSS THE AREA
AND WOULD NOT BE SURPRISED TO SEE THESE WINDS REACH ADVISORY LEVELS
IN SOME AREAS.

&&

.AVIATION...11/1200Z.

HIGH CONFIDENCE IN VFR CONDS ARE EXPECTED THROUGH THE PERIOD. THERE
WILL BE SOME AREAS OF LLWS AND MODERATE TURBULENCE ACROSS THE AREA
THROUGH AROUND 16Z DUE TO THE NORTH TO NORTHEAST FLOW ALOFT...MOST
LIKELY AT KBUR...KVNY...AND KSBA.

KLAX...HIGH CONFIDENCE IN CURRENT TAF. THERE IS A 30 PERCENT CHANCE
THE NORTHEASTERLY WINDS COULD GUSTS TO 10 KT...BUT WILL NOT LAST
BEYOND 16Z.

KBUR...HIGH CONFIDENCE IN CURRENT TAF. AREAS OF LLWS AND TURBULENCE
WILL CONTINUE THROUGH AROUND 16Z NEAR THE AIRFIELD DUE TO THE NORTH
TO NORTHEAST FLOW ALOFT. THERE IS A 30 PERCENT CHANCE AFTERNOON
WINDS WILL BE NORTHERLY INSTEAD OF USUAL SOUTHERLY.


***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...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).

&&

$$

PUBLIC...RK/THOMPSON
AVIATION...MEIER
SYNOPSIS...HOFFER

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NWS LOX Office Area Forecast Discussion

Glendora Random Weather Fact

HEAT INDEX
The Heat Index (HI) (or apparent temperature) is a measure of relative discomfort due to combined heat and high humidity. It was developed by R.G. Steadman (1979) and is based on physiological studies of evaporative skin cooling for various combinations of ambient temperature and humidity. As temperatures climb above 90 °F and humidity goes above 40 percent, conditions are ripe for heat-related illnesses.