462 FXUS66 KLOX 140435 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 935 PM PDT TUE OCT 13 2015 .SYNOPSIS... A LOW PRESSURE SYSTEM TO THE SOUTHWEST WILL BRING A POSSIBILITY OF SHOWERS AND THUNDERSTORMS WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT BEFORE BECOMING CONFINED TO THE MOUNTAINS ON FRIDAY. A COOLING TREND WILL DEVELOP THROUGH THE WEEKEND AS ANOTHER LOW PRESSURE SYSTEM TO BRING POSSIBLE SHOWERS AND NORMAL TEMPERATURES ON SUNDAY. A HIGH WILL MOVE IN NEXT WEEK FOR A WARMING TREND AND WELL ABOVE NORMAL TEMPERATURES. && .UPDATE... ANOTHER WARM AND HUMID NIGHT ACROSS THE AREA THIS EVENING. DEWPOINTS AT COASTAL TERMINALS ARE IN THE LOWER 70S. PATCHY DENSE FOG IS DEVELOPING AS TEMPERATURE AND DEWPOINT SPREADS NARROW. A BALMY NIGHT LOOKS ON TAP...MORE SIMILAR TO THE SOUTHEASTERN UNITED STATES THAN SOUTHERN CALIFORNIA. WITH STRATUS DEVELOPING OVERNIGHT LOW TEMPS MAY NOT GET MUCH LOWER FOR THE COASTAL AREAS. MINIMUM TEMPERATURES IN THE MID 60S TO MID 70S WILL BE PREVALENTS ACROSS MOST COASTAL AND VALLEY AREAS TONIGHT. THE MINIMUM TEMPERATURES WILL WARMED IN THE LATEST FORECAST UPDATE FOR TONIGHT. MODEL SOLUTIONS HANDLING THE TROUGH SIMILAR TO THE PREVIOUS SHIFT...BUT GFS AND NAM-WRF SOLUTION DO DEVELOP A WARM AIR ADVECTIVE PATTERN FOR WEDNESDAY ACROSS THE SOUTH COAST OF SANTA BARBARA COUNTY THROUGH VENTURA COUNTY AND INTO THE SANTA MONICA MOUNTAINS. POPS WILL BE INCREASED ACROSS THESE AREAS. AN UPDATE WILL ISSUED SHORTLY. && .PREV DISCUSSION... SHORT TERM...MODELS DO SHOW SEVERAL SMALL VORTS ROTATING AROUND THE LOW AND INTO THE AREA WEDNESDAY, BUT MORE SO ON THURSDAY WITH THE LOW BASICALLY OVERHEAD. THUS, POPS ARE HIGHER ON THURSDAY WITH THE BEST CHANCES OVER THE MTNS. STEERING FLOW IS FAIRLY STRONG WEDNESDAY, AROUND 20 KT OR SO, BUT WEAKER ON THU. PWATS ALSO A BIT HIGHER THU. SO WHILE SHOWERS COULD BRIEFLY BE HEAVY WEDNESDAY, THE RISK FOR ANY FLOODING ASSOCIATED WITH THUNDERSTORMS IS A BIT HIGHER THU DUE TO THE SLOWER MOVEMENT AND HIGHER PWATS. AS WITH MOST UPPER LOWS LIKE THIS, SHOWERS AND STORMS WILL BE HIT AND MISS. SOME PLACES WON'T GET ANY RAIN (OR JUST SPRINKLES) WHILE OTHERS COULD GET A HALF INCH OR MORE. TEMPS WILL COOL A BIT THE NEXT COUPLE DAYS WITH THE UPPER LOW AND INCREASED CLOUD COVER AND SHOWERS. STILL ABOVE NORMAL AND HUMIDITIES, WHICH ALREADY WERE HIGHER TODAY, SHOULD BE HIGHER THE NEXT COUPLE DAYS AS WELL. SO IT LIKELY WON'T FEEL A LOT COOLER EVEN THOUGH TEMPS WILL DROP 5-10 DEGREES FROM TODAY. THE LOW IS EXPECTED TO EXIT THE AREA FRIDAY. COULD STILL BE SOME ISOLATED SHOWER/STORM ACTIVITY ACROSS INTERIOR AREAS BUT OTHERWISE MOST AREAS WILL BE DRY WITH THE FLOW ALOFT SHIFTING TO THE NORTH. LITTLE CHANGE IN TEMPS EXPECTED BUT SLIGHTLY LOWER HUMIDITIES. LONG TERM...FAIRLY QUIET WEATHER DAY MOST OF SATURDAY AS A BRIEF LITTLE RIDGE POPS UP BETWEEN UPPER LOWS. SOUTHERN AREAS SHOULD SEE SLIGHT WARMING BUT OTHERWISE LITTLE CHANGE IN TEMPS EXPECTED. SAT NIGHT INTO SUNDAY THE NEXT UPPER LOW WILL DROP INTO THE AREA FROM THE NORTH. THERE'S BEEN A LOT OF VARIABILITY IN THE MODELS, ESPECIALLY THE ECMWF, WHICH LAST NIGHT WAS SHOWING CLOSE TO 3" OF RAIN IN LA COUNTY SUNDAY AND TODAY REMOVED RAIN ALMOST ENTIRELY. THE GFS HAS SHOWN LESS WOBBLING, AND HAS ACTUALLY TRENDED DEEPER WITH THE TROF BUT STILL VERY MUCH OVER LAND, MEANING DRIER. THE GFS ENSEMBLE MEAN ALSO KEEPS MOST OF THE AREA DRY WITH THIS SYSTEM. SO WITH THE 12Z MODELS ALL IN PRETTY GOOD AGREEMENT LEANING TOWARDS A DRIER SOLUTION I'VE LOWERED POPS BUT NOT REMOVED THEM. WILL KEEP A SLIGHT CHANCE GOING ALL AREAS AND HOPE FOR SOME BETTER CONSISTENCY OVER THE NEXT COUPLE DAYS. HIGH TEMPS EXPECTED TO BE NEAR NORMAL SUNDAY WITH THE UPPER LOW OVERHEAD, THEN RAPID WARMING THROUGH THE MIDDLE OF NEXT WEEK AS THE RIDGE QUICKLY BUILDS BEHIND IT. WARMER VALLEYS EXPECTED TO BE BACK IN THE 90S BY TUESDAY. && .AVIATION...14/0000Z. AT 0000Z...THERE WAS NO MARINE INVERSION AT KLAX. OVERALL MODERATE TO HIGH CONFIDENCE IN 00Z TAFS. VFR CONDITIONS WILL CONTINUE THROUGH MOST OF THE PERIOD AS MID TO UPPER LEVEL CLOUDS MOVE OVER THE AREA. THERE IS A 10% CHANCE OF MVFR CONDS DEVELOPING ACROSS COASTAL AREAS OVERNIGHT. THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE AREA AFTER 18Z WED. ANY THUNDERSTORMS THAT DEVELOP WILL BE CAPABLE OF PRODUCING BRIEF HEAVY SHOWERS AND GUSTY ERRATIC WINDS. KLAX AND KBUR...VFR CONDITIONS EXPECTED THROUGH WEDNESDAY. THERE IS A 10 PERCENT CHANCE OF MVFR CONDS AFTER 08Z TONIGHT...AND A SLIGHT CHANCE OF THUNDERSTORMS AFTER 18Z WED. && .MARINE...13/900 PM. HIGH CONFIDENCE IN THE MARINE FORECAST. WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THURSDAY MORNING. THERE IS A 50 PERCENT CHANCE OF SMALL CRAFT ADVISORY WINDS FROM THE NORTHWEST THURSDAY AFTERNOON AND EVENING AND AGAIN ON FRIDAY IN THE OUTER WATERS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS WEDNESDAY AFTERNOON THROUGH THURSDAY EVENING AS AN UPPER LOW DRIFTS NORTH TO NORTHEAST ACROSS THE COASTAL WATERS. && .LOX WATCHES/WARNINGS/ADVISORIES... SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX). && $$ PUBLIC...HALL/MW AVIATION...SMITH MARINE...SMITH SYNOPSIS...SETO/HALL WWW.WEATHER.GOV/LOSANGELES