Southwestern California Discussion
000
FXUS66 KLOX 031146
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
445 AM PDT FRI SEP 3 2010
...NEW AVIATION DISCUSSION...
.SYNOPSIS...
HIGH PRESSURE ALOFT WILL MAINTAIN HOT WEATHER INLAND THROUGH
SATURDAY. COOLER CONDITIONS WILL PREVAIL NEAR THE COAST...ALONG
WITH PATCHY NIGHT THROUGH MORNING LOW CLOUDS AND FOG. A TROUGH OF
LOW PRESSURE WILL MOVE INTO THE WESTERN STATES ON SUNDAY...CAUSING
COOLING ACROSS REGION. AN UPPER LOW DROPPING DOWN THE WEST COAST
WILL MAINTAIN COOL CONDITIONS FOR MUCH OF NEXT WEEK...WITH NIGHT
THROUGH MORNING LOW CLOUDS IN COASTAL AND VALLEY AREAS.
&&
.SHORT TERM (TODAY-SUN)...AMDAR SOUNDINGS SHOWED MARINE LAYER WAS
RUNNING AROUND 800 FEET DEEP EARLY THIS MORNING. LOW CLOUDS AND
AREAS OF DENSE FOG HAVE PUSHED ACROSS MOST OF THE CSTL PLAIN.
A DENSE FOG ADVISORY IS IN EFFECT FOR ALL CSTL AREAS UNTIL 9 AM.
CLOUDS AND FOG SHOULD BURN OFF QUICKLY THIS MORNING AWAY FROM THE
COAST...BUT WITH SUCH A STRONG INVERSION...THERE IS A CHANCE THAT
CLOUDS COULD LINGER INTO THE AFTERNOON HOURS NEAR THE BEACHES...
ESPECIALLY S OF PT CONCEPTION.
PROFILER DATA SHOWS A COUPLE OF DEGREES C OF WARMING ABOVE 1000 FT
DURING THE PAST 24 HOURS. THEREFORE...EXPECT MAX TEMPS TO BE UP A
BIT IN MOST AREAS...WITH HIGHS LIKELY PEAKING OUT AT OR JUST ABOVE
105 DEGREES IN THE HOTTER LOCATIONS IN THE VLYS...DESERTS...AND
ACROSS LOWER ELEVATIONS IN THE MTNS. WHILE AMBIENT TEMPS WILL BE
QUITE HIGH...IT WILL BE VERY DRY...SO HEAT INDEX VALUES WILL
ACTUALLY BE LOWER THAN THE AIR TEMPS. THE MARINE INFLUENCE WILL BE
STRONG ENOUGH TO KEEP MOST OF THE COASTAL PLAIN COMFORTABLE... WITH
ONLY INLAND SECTIONS OF THE L.A. COUNTY CSTL PLAIN HAVING ANY GOOD
CHANCE OF REACHING 90 DEGREES. IN THE HILLS TO THE N OF THE
CITY...THOUGH...TEMPS WILL LIKELY BE IN THE 90S TO AROUND 100
TODAY.
THE WRF SHOWS N-S GRADS BECOMING INCREASINGLY OFFSHORE TONIGHT...
AND W-E SFC PRES GRADS FLIPPING WKLY OFFSHORE TONIGHT AND EARLY SAT.
IT ALSO SHOWS SOME WEAK LOW LVL NELY FLOW AT 950 MB. THE WRF SUGGESTS
THE ENTIRE REGION WILL BE CLEAR TONIGHT...BUT WITH THE LACK OF A
STRONG OFFSHORE PUSH...IT IS DOUBTFUL THAT THIS STUBBORN STRATUS
LAYER WILL GO AWAY COMPLETELY. STILL...COVERAGE MAY BE LIMITED TO
THE IMDT BEACH AREAS. 950 MB TEMPS ARE ACTUALLY FCST TO WARM A BIT
ON SAT...ESPECIALLY ACROSS THE COASTAL PLAIN. THIS COULD ALLOW FOR A
BIT MORE WARMING...ESPECIALLY ACROSS THE CSTL PLAIN...AND FAR INLAND
AREAS OF THE L.A. COUNTY CSTL PLAIN HAVE A CHANCE OF TEMPS RISING
WELL INTO THE 90S ON SAT.
THE UPPER HIGH OVER THE REGION WILL BEGIN TO WEAKEN AND SHIFT EWD
SAT NIGHT AND SUNDAY AS A TROUGH DROPS THROUGH THE PAC NW. EXPECT
SOMEWHAT BETTER INLAND PENETRATION OF THE LOW CLOUDS SAT NIGHT/EARLY
SUNDAY...AND SOME CLOUDS COULD SQUEAK INTO THE SAN GABRIEL VALLEY
LATE SAT NIGHT/SUN MORNING. MAX TEMPS WILL BE DOWN IN ALL AREAS ON
SUNDAY...MOST SIGNIFICANTLY IN THE VALLEYS AND ACROSS INTERIOR
SECTIONS OF THE CSTL PLAIN...WHERE MAX TEMPS MAY BE DOWN 10 TO 15
DEGREES FROM THOSE ON SAT.
.LONG TERM (MON-THU)...A BROAD TROUGH WILL LINGER ACROSS THE REGION
MON AND TUE. EXPECT NIGHT THROUGH MORNING LOW CLOUDS TO PUSH INTO
THE VLYS...AND AFTER SEVERAL MORE DEGREES OF COOLING ON MONDAY...MAX
TEMPS WILL LIKELY LEVEL OFF OR DROP SLIGHTLY ON TUE. THE GFS SHOWS
AN UNSEASONABLY STRONG UPPER LOW DROPPING SWD DOWN THE W COAST ON
WED...AND PUSHING INTO CA JUST N OF THE REGION ON THU. THE ECMWF
IS SIMILAR...BUT SHOWS MORE OF A SHARP TROUGH MOVING THRU NRN AND
CENTRAL CA WED THROUGH THU. AT THE VERY LEAST...THESE PATTERNS WOULD
LIKELY DEEPEN THE MARINE LAYER ENOUGH TO SEND CLOUDS TO THE CSTL
SLOPES AND CAUSE ADDITIONAL COOLING ON WED AND THU. BOTH MODELS
ACTUALLY SHOW SOME LIGHT AMOUNTS OF MEASURABLE RAIN WED NIGHT AND
EARLY THU ACROSS PARTS OF THE REGION...BUT THAT IS A LONG WAY
AWAY TO FCST SOMETHING SO ANOMALOUS FOR EARLY SEPTEMBER.
&&
.AVIATION...03/1145Z.
WIDESPREAD DENSE FOG IS LIKELY TO CONTINUE DURING THE NIGHT AND
EARLY MORNING HOURS IN THE IMMEDIATE COASTAL SECTIONS. THE AFTERNOON
WILL BRING A BRIEF RESPITE FROM LIFR CEILINGS AND VISIBILITY.
FURTHER INLAND...CONDITIONS WILL REMAIN VFR THROUGH SATURDAY. GOOD
CONFIDENCE IN THE FORECAST.
KLAX...GOOD CONFIDENCE IN LIFR CONDITIONS DURING THE NIGHT AND EARLY
MORNING HOURS WITH BRIEF CLEARING DURING THE LATE MORNING THROUGH
EARLY AFTERNOON.
KBUR...HIGH CONFIDENCE IN VFR CONDITIONS THROUGH SATURDAY.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY (SEE LAXNPWLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
&&
$$
PUBLIC...BRUNO
AVIATION...SWEET
SYNOPSIS...DB
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NWS LOX Office Area Forecast Discussion
