000
FXUS66 KLOX 181830
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1130 AM PDT THU SEP 18 2008

NEW AVIATION DISCUSSION

.SHORT TERM...
OFFSHORE TRENDS AND MUCH ABOVE NORMAL 850 MB HUMIDITIES HAVE DONE A
NUMBER ON THE MARINE LAYER WITH ONLY PATCHY LOW CLOUDS AROUND THE
L.A. AND CATALINA COASTS. SMALL WORRY WITH THOSE HIGH 850 DEW POINTS
INTERACTING WITH A SMALL DEFORMATION ZONE AND BUBBLING UP SOME
CONVECTION EARLY THIS MORNING...BUT SATELLITE SHOWS NO ACTIVITY AND
KEPT MENTION OUT OF THE FORECAST BUT WILL HAVE TO MONITOR. THIS
AFTERNOON THAT SAME MOISTURE WILL CAUSE PARTLY CLOUDY SKIES AND A
SLIGHT CHANCE OF TSTMS OVER THE VTA AND LA MTNS AS WELL AS THE
ANTELOPE VALLEY.

MDLS CONTINUE TO SHOW NO MARINE LAYER TONIGHT AS THEY HAVE BEEN FOR
THE PAST FEW DAYS AND GIVEN THE CLEAR SKIES AT THE MOMENT WILL KEEP
SKIES CLEAR. TEMPS WILL BE VERY SIMILAR TO TODAYS VALUES BUT SINCE
THERE WILL BE NO MID LEVEL MOISTURE THERE WILL BE NO TSTM THREAT.

IN THE WAKE OF A WEAK TROF ONSHORE FLOW SHOULD INCREASE ENOUGH TO
BRING MARINE CLOUDS BACK TO THE CENTRAL COAST. THERE IS A CHANCE OF
LOW CLOUDS SOUTH OF POINT CONCEPTION BUT FOR NOW WILL LEAVE THEM OUT.

LOOK FOR A WEAK SUNDOWNER BOTH TONIGHT AND FRIDAY NIGHT WITH A
LITTLE NW UPPER PUSH AND A MINUS 3 SMX-SBA GRADIENT.

.LONG TERM...
MEDIUM RANGE MDLS HAVE FINALLY COME INTO SOME SORT OF AGREEMENT FOR
THE EXTENDED FORECAST. THE WEEKEND LOOKS FAIRLY BLAND WITH A FLAT
TROF SITTING OVER THE WEST COAST. THIS SHOULD BRING THE MARINE LAYER
BACK TO THE COASTAL SECTIONS AND MAYBE SOME PATCHES INTO THE COASTAL
VLYS. A LITTLE LOWER HGTS AND STRONGER ONSHORE FLOW WILL DROP TEMPS
A FEW MORE DEGREES. THE TROF SHARPENS AND DIVES SOUTH MONDAY AND
EXITS EARLY TUESDAY AND THIS SHOULD LIFT THE MARINE LAYER INTO THE
VLYS. A HIGH WILL BUILD INTO NEVADA IN THE WAKE OF THIS TROF AND BY
WEDNESDAY THE FIRST OFFSHORE EVENT OF THE SEASON COULD SHAPE UP. BUT
THE GFS IS A LITTLE OFFSHORE HAPPY AND THIS FORECAST COULD CHANGE BY
THEN.

&&

.AVIATION...18/1830Z.
MOSTLY CLEAR SKIES WILL CONTINUE THROUGH THIS EVENING BEFORE LOW
CLOUDS AND FOG RETURN TO ALL THE COASTAL TAFS SOMETIME AROUND
MIDNIGHT...GIVE OR TAKE A COUPLE OF HOURS. MVFR TO IFR CONDITIONS
ARE THEN EXPECTED THROUGH MID MORNING ON FRIDAY. VALLEY TAFS WILL
LIKELY REMAIN CLEAR THROUGH FRIDAY.

KLAX...CLEAR SKIES THROUGH ABOUT MIDNIGHT...THEN A 70 PERCENT CHANCE
OF LOW CLOUDS AND FOG WITH MVFR TO IFR CONDITIONS FROM MIDNIGHT
THROUGH MID MORNING FRIDAY.

KBUR...A 70 PERCENT CHANCE OF CLEAR SKIES THROUGH FRIDAY.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...RORKE
AVIATION...SWEET

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