855 
FXUS66 KLOX 051750
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1049 AM PDT THU JUL 5 2012

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

ONSHORE FLOW WILL KEEP TEMPERATURES BELOW NORMAL TODAY AND TOMORROW. 
CLOUDS WILL BE SLOW TO CLEAR IN MOST VALLEYS...WITH MINIMAL CLEARING 
NEAR THE COAST. HIGH PRESSURE WILL PUSH THE CLOUDS OUT OF THE 
VALLEYS THIS WEEKEND AND TEMPERATURES WILL RISE ABOVE NORMAL THROUGH 
THE MIDDLE OF NEXT WEEK...ESPECIALLY FOR INLAND AREAS.

&&

.SHORT TERM (TODAY-SUN)...MARINE LYR HAS DEEPENED TO CLOSE TO 3000 
FEET THIS MORNING, SO THE LOWERING TREND CERTAINLY DIDN'T WORK OUT. 
GRADIENTS ARE STARTING TO TREND OFFSHORE THOUGH AND MODELS DO 
INDICATE SOME WARMING COMING IN ALOFT THIS AFTERNOON AS THE RIDGE 
STARTS TO EXPAND WESTWARD. SO THERE IS SOME HOPE FOR BETTER CLEARING 
TODAY THAN WEDNESDAY. LOCAL PROFILERS DO SHOW A LITTLE WARMING IN 
THE LOWER LEVELS FROM YESTERDAY SO INLAND VALLEYS AT LEAST SHOULD 
SEE A DEGREE OR TWO OF WARMING OVER WEDNESDAY. THE MONSOON MOISTURE 
HAS SHIFTED WELL EAST SO NO TSTORMS EXPECTED ACROSS NE LA COUNTY 
THIS AFTERNOON. COULD STILL GET A FEW AFTERNOON CU THOUGH.

FOR FRIDAY THE EXPECTATION IS THAT THE WARMING ALOFT WILL CONTINUE, 
RESULTING IN A LOWER MARINE LYR DEPTH AND WARMER TEMPERATURES, 
ESPECIALLY ACROSS THE VALLEYS. 

***FROM PREVIOUS DISCUSSION***

THE JUNE LIKE WEATHER WILL BEGIN TO TURN MORE SUMMER LIKE STARTING 
SATURDAY. THE UPPER HIGH THAT HAS DOMINATED THE MIDWEST'S WEATHER 
WILL EXPAND WESTWARD. THIS WILL INCREASE THE HGTS WHICH WILL SMOOSH 
THE MARINE LAYER AND WILL ALSO REDUCE THE ONSHORE FLOW. BOTH OF 
WHICH SHOULD PUSH THE MARINE LAYER OUT OF THE VLYS EXCEPT THE SAN 
GABRIEL. THAT SAID THERE IS ABOUT A 40 PERCENT CHANCE THAT THE 
CLOUDS WILL HANG AROUND ONE MORE DAY AS IT COULD TAKE A LITTLE EXTRA 
TIME TO MOVE THE WELL ESTABLISHED MARINE LAYER OUT OF THE VLYS. THE 
INTERIOR WILL START TO WARM. THE VLYS WILL HAVE A NICE JUMP IN TEMPS 
IF THE MARINE LAYER IS INDEED GONE NOT SO MUCH IF IT IS STILL AROUND 
AND THE COASTS WILL REMAIN COOL.

BY SUNDAY THE UPPER HIGH WILL BE CENTERED OVER UTAH AND THERE WILL 
BE 591 DM HGTS OVER SO CAL. THIS WILL CONFINE THE MARINE LAYER TO 
THE COAST. THERE WILL BE FURTHER WARMING ACROSS ALL NON COASTAL 
AREAS. THE ONE COASTAL WORRY WILL BE THE STRENGTHENING OF THE MARINE 
INVERSION WHICH COULD MAKE IT TOUGH TO MIX OUT THE MARINE CLOUDS.

.LONG TERM (MON-WED)...
THREE DAYS OF THE SAME FOR THE EXTENDED. A HUGE HOT 595DM UPPER HIGH 
OVER UTAH WILL SIT IN PLACE. MAX TEMPS WILL RISE AS WILL MIN TEMPS. 
THE MARINE LAYER WILL BE CONFINED TO THE COASTS AND COULD HAVE A 
HARD TIME CLEARING DUE TO THE VERY STRONG INVERSION. SOME AREAS 
RIGHT AT THE TOP OF THE INVERSION WILL HAVE VERY LITTLE RELIEF 
OVERNIGHT WITH LOWS LIKELY STAYING IN THE 70S. TRIPLE DIGIT MAX 
TEMPS WILL BE COMMON IN THE DESSERTS AND THERE WILL LIKELY BE A FEW 
TRIPLE DIGIT READINGS IN THE WARMEST VLY LOCATIONS AS WELL. THE 
POSITION OF THE UPPER HIGH WILL OPEN THE DOOR TO THE MONSOON FLOW 
AND LOOK FOR PARTLY CLOUDY SKIES WITH A SLIGHT CHC OF TSTMS OVER THE 
L.A. MTNS AND THE AV EACH AFTERNOON AND EVENING.

&&

.AVIATION...05/1800Z...
EXPECT BETTER CLEARING TODAY COMPARED TO PREVIOUS DAYS...WITH VALLEY 
AIRFIELDS CLEAR BY 19Z-20Z...AND MANY OF THE COASTAL SITES SHOULD 
HAVE A FEW HOURS OF VFR CONDS BETWEEN 22Z-03Z. THERE IS A 30% CHANCE 
THAT SOME COASTAL SITES WILL EXPERIENCE VERY BRIEF OR NO CLEARING. 

RISING HEIGHTS AND WARMING ALOFT WILL PRODUCE A SHALLOWER MARINE 
LAYER TONIGHT...WITH MVFR/IFR CIGS EXPECTED OVER THE COAST AND 
NEAR-COASTAL VALLEY LOCATIONS FOR THE OVERNIGHT PERIOD...AND IN 
SALINAS RIVER VALLEY.   

KLAX...MODERATE CONFIDENCE IN 18Z TAF. THERE IS A 30% CHANCE THAT 
THE MVFR CIGS WILL NOT CLEAR OUT THIS AFTERNOON. THERE IS A 20 
PERCENT CHANCE THAT CIGS WILL REMAIN MVFR OVERNIGHT. 

KBUR...MODERATE TO HIGHER CONFIDENCE IN 18Z TAF. STRATUS COULD CLEAR 
1-2 HRS LATER THAN CURRENT 19Z FORECAST. RETURN OF STRATUS AND LOWER 
VSBY COULD OCCUR +/- 2 HRS FROM TAF TIME OF 08Z TONIGHT. 

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...MW/RORKE
AVIATION...SMITH
SYNOPSIS...SETO

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