000
FXUS66 KLOX 152044
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
145 PM PDT WED OCT 15 2008
.SHORT TERM (TODAY-SAT)...OFFSHORE FLOW WILL BE WEAKENING THROUGH
SATURDAY. UPPER SUPPORT IS ALREADY GONE SO ANY WIND WILL BE HIGHLY
LOCALIZED AND MOSTLY UNDER 25 MPH. HOWEVER, HUMIDITIES REMAIN VERY
LOW ACROSS THE VALLEYS AND MOUNTAINS SO THE RED FLAG WARNINGS HAVE
BEEN EXTENDED THROUGH FRIDAY. NOT MUCH CHANGE IN TEMPERATURES
THROUGH FRIDAY, THOUGH THE SEABREEZE SHOULD START A LITTLE SOONER
EACH DAY, PROVIDING A FEW DEGREES OF COOLING RIGHT AT THE IMMEDIATE
COAST.
TRICKY FORECAST FOR SATURDAY. GFS HAS BEEN ADVERTISING A NARROW BUT
SIGNIFICANT PLUME OF MOISTURE BEING PULLED NORTHWARD INTO VENTURA
AND LA COUNTIES FROM A TROF JUST OFF THE COAST. UNTIL TODAY THE
ECMWF WAS IN DECENT AGREEMENT WITH THIS. HOWEVER, THE 12Z ECMWF CAME
IN DRIER, AND THE 12Z NAM CONTINUES TO BE BONE DRY. SO FOR NOW I`VE
DECIDED NOT TO INTRODUCE ANY THREAT OF SHOWERS TO THE TEXT FORECAST,
BUT HAVE LEFT 5-10 POPS IN THE GRIDS. IN ANY CASE, A STRONG ONSHORE
TREND IN THE GRADIENTS SATURDAY COMBINED WITH THE APPROACHING TROF
SHOULD CAUSE TEMPS TO DROP AT LEAST 10 DEGREES IN MOST AREAS.
.LONG TERM (SUN-WED)...THE TROF WILL CONTINUE TO DEEPEN OVER SRN CAN
THROUGH MONDAY MORNING BEFORE MOVING EAST. WITH THE ONSHORE FLOW
INCREASING WE WILL LIKELY SEE A RETURN OF THE MARINE LYR AT LEAST TO
THE COASTAL ZONES AND POSSIBLY REACHING THE VALLEYS AS WELL. HIGHS
WILL DROP A FEW DEGREES BELOW NORMAL, BUT SKIES SHOULD CLEAR OUT
EACH DAY.
CONSIDERABLE UNCERTAINTY EXISTS IN THE FORECAST FROM TUESDAY ON. THE
12Z ECMWF CAME IN MUCH MORE PROGRESSIVE WITH THE NEXT TROF THAN
EARLIER RUNS, WHICH HAD SHOWN ANOTHER COLD UPPER LOW DROPPING INTO
NEVADA FOR THE MIDDLE OF NEXT WEEK. THE GFS HAS ALWAYS BEEN WARMER
AND MUCH MORE PROGRESSIVE. CONSIDERING WE JUST HAD A COLD INSIDE
SLIDER UPPER LOW FOLLOWED BY STRONG OFFSHORE SURFACE FLOW THE EC
SOLUTION FOR NEXT WEEK SEEMED REASONABLE. BUT NOW WITH IT SHIFTING
GEARS AND ALLIGNING WITH THE GFS, AND WITH VIRTUALLY ALL THE
ENSEMBLE MEMBERS SHOWING A STRONG UPPER RIDGE FOR WED, IT WOULD SEEM
THAT A WARMER SOLUTION WITH WEAKER OFFSHORE FLOW WOULD BE WARRANTED.
HOWEVER, I STILL THINK THERE IS A GOOD CHANCE THAT AT LEAST ONE OF
THE MODELS WILL REVERT BACK TO A COLDER SOLUTION WITH STRONGER
OFFSHORE FLOW SO FOR NOW I`M GOING TO LEAVE THE WED FORECAST AS IS.
&&
.AVIATION...15/1645Z.
CLEAR SKIES ARE EXPECTED TO CONTINUE THROUGH THURSDAY. WEAK OFFSHORE
PRESSURE GRADIENTS WILL PRECLUDE THE POSSIBILITY OF ANY WIND ISSUES.
KLAX AND KBUR...CLEAR SKIES AND TYPICAL BREEZES THROUGH THURSDAY.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING (SEE LAXRFWLOX).
&&
$$
PUBLIC...WOFFORD
AVIATION...SWEET
WWW.WEATHER.GOV/LOSANGELES
