Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000 FXUS66 KLOX 010038 AAA AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 540 PM PDT TUE JUN 30 2015 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... A WARM AND HUMID AIR MASS WILL CONTINUE OVER THE AREA THROUGHOUT THE WEEK AS HIGH PRESSURE REMAINS OVER THE GREAT BASIN. SOUTHEAST FLOW ALOFT...MOIST AND UNSTABLE AIR WILL CONTINUE A SLIGHT CHANCE OF THUNDERSTORMS AND SHOWER OVER THE MOUNTAINS AND DESERTS WITH SOME LIGHT SPRINKLES OR SHOWERS POSSIBLE WEDNESDAY ACROSS THE COAST AND VALLEYS. A COOLING TREND IS EXPECTED TOWARD THE WEEKEND AS LOW PRESSURE APPROACHES. && .SHORT TERM (TODAY-FRI)...ANOTHER HOT DAY ACROSS THE AREA UNDER AMPLE SUNSHINE AND WEAK ONSHORE FLOW. HAVE HAD SOME SMALL CU POP UP ACROSS THE MTNS AND AV BUT FAR TOO WEAK TO GENERATE ANY PRECIP YET. STILL ENOUGH HEATING LEFT TODAY TO KEEP THE THUNDER THREAT GOING THROUGH EARLY EVENING IN THOSE AREAS SO NO CHANGES THERE. STILL CLOSELY MONITORING THE MOISTURE AND CONVECTION NOW ACROSS THE BORDER INTO THE US AND INTO SAN DIEGO COUNTY. WILL SEE THE REMNANTS OF THIS MOVE INTO THE SRN PORTION OF OUR FORECAST AREA LATER THIS AFTERNOON AND EVENING BUT SHOULDN`T BE MUCH OF AN IMPACT OTHER THAN THE INCREASE IN CLOUDS AND MAYBE A SPRINKLE OR TWO IN THE SOUTH. IT`S THE SECOND BATCH OF MOISTURE AND CONVECTION THAT IS JUST DEVELOPING SOUTH OF TUCSON THAT WILL SPREAD NORTHWEST OVERNIGHT AND BRING INCREASING CLOUDS AND POSSIBLY SOME SPRINKLES OR LIGHT SHOWERS TO THE AREA LATER TONIGHT AND WEDNESDAY. MODELS STILL SHOWING VERY LITTLE INSTABILITY WITH THIS WHEN IT COMES THROUGH OUR AREA, LIKELY IN PART DUE TO THE THICK MID/HIGH LEVEL CLOUD COVER, AND FOR NOW HAVE LEFT THUNDER OUT OF THE COAST AND COASTAL VALLEY ZONES. NOT VERY KEEN ON THE MTN/AV THUNDERSTORMS EITHER FOR THE SAME REASON BUT IF CLOUDS ARE NOT AS THICK AS EXPECTED AND WE CAN GET SOME ADDITIONAL SURFACE HEATING THEN THERE COULD ENOUGH TO GENERATE AN ISOLATED STORM OR TWO. FOR NOW, THE FORECAST IS PREDICATED ON A THICKER CLOUD SHIELD COOLING TEMPS SEVERAL DEGREES FROM TODAY, THOUGH THE INCREASING HUMIDITY WILL OFFSET SOME OF THE COOLING EFFECTS. THE MOISTURE IS EXPECTED TO DECREASE LATE WEDNESDAY INTO THURSDAY, LEADING TO DECREASING CLOUDS AND MINIMAL RAIN CHANCES. STILL SOME SMALL CHANCES ACROSS THE MTNS AND AV THU AFTERNOON THOUGH AGAIN MODELS ARE INDICATING MINIMAL INSTABILITY. BETTER HEATING THOUGH WITH THE DECREASED CLOUD COVER SO POSSIBLY ENOUGH SURFACE HEATING TO GET A STORM OR TWO TO POP. SOME COAST/VALLEY AREAS LIKELY TO SEE AT LEAST A FEW DEGREES OF WARMING THU WITH MORE SUN THAN WED. MOISTURE CONTINUES TO DECREASE FRIDAY WITH PWATS DOWN TO AROUND AN INCH IN MOST AREAS. AM LEAVING IN THE SMALL MTN/AV POPS FOR THE AFTERNOON AGAIN BUT IF NOTHING HAPPENS THU THEN FRIDAY WILL LIKELY BE QUIET AS WELL. A SLIGHT INCREASE IN ONSHORE FLOW SHOULD BRING A FEW DEGREES OF COOLING TO MOST AREAS. .LONG TERM (SAT-TUE)...TEMPS EXPECTED TO RETURN TO NEAR NORMAL LEVELS OVER THE WEEKEND INTO EARLY NEXT WEEK AS A WEAK TROF DEVELOPS TO THE NORTH AND THE FLOW ALOFT VEERS FROM SOUTHEAST TO SOUTHWEST. THIS WILL SHUT DOWN THE MONSOON CONNECTION AND BRING A RETURN TO TYPICAL NIGHT/MORNING LOW CLOUDS/FOG WITH NO THREAT OF AFTERNOON CONVECTION. THE GFS SHOWS THIS PATTERN LASTING INTO NEXT WEEKEND, HOWEVER THE ECMWF WANTS TO BRING THE HIGH BACK WEST AND PUSH THAT NRN CA TROF FURTHER OFF THE COAST. THIS WOULD CERTAINLY BE A WARMER SOLUTION AND COULD OPEN THE DOOR FOR MORE MONSOON MOISTURE FOR THE LATTER HALF OF NEXT WEEK. && .AVIATION...01/0030Z... AT 2350Z...THE MARINE INVERSION AT KLAX WAS 500 FT DEEP. THE TOP OF THE INVERSION WAS AT 2000 FT WITH A TEMPERATURE OF 26 DEG C. GENERALLY HI CONFIDENCE IN THE 00Z TAFS. LOW CLOUDS WITH LIFR/IFR CONDITIONS ARE EXPECTED AT THE COASTAL AIRFIELDS AT TIMES TONIGHT AND WED MORNING...WITH THE ONSET OF THE LOW CLOUDS RANGING FROM 04Z AT KOXR TO 13Z AT KLGB. THE TIMING OF THE ONSET AND DISSIPATION OF THE LOW CLOUDS MAY BE OFF PLUS/MINUS AN HOUR OR TWO. OTHERWISE...VFR CONDITIONS FOR THE MOST PART WILL PREVAIL AT THE AIRFIELDS THRU WED. GUSTY SW WINDS AT KWJF AND KPMD WILL DIMINISH THIS EVENING THEN INCREASE AGAIN WED AFTERNOON. KLAX...GENERALLY HI CONFIDENCE IN THE 00Z TAF. VFR CONDITIONS ARE EXPECTED FOR THE MOST PART THROUGH WED EVENING. HOWEVER...THERE IS A 60-70 PERCENT CHANCE OF LOW CLOUDS AND IFR CONDITIONS FROM ABOUT 12Z- 17Z...WITH THE TIMING OF ONSET AND DISSIPATION POSSIBLY OFF PLUS/MINUS AN HOUR OR TWO. KBUR...HI CONFIDENCE IN THE 00Z TAF WITH VFR CONDITIONS EXPECTED THRU WED AFTERNOON. && .MARINE...30/200 PM. SMALL CRAFT ADVISORY CONDITIONS ARE NOT EXPECTED THROUGH FRIDAY MORNING. THERE IS A CHANCE SCA CONDITIONS WITH WEST WINDS WILL EXIST OVER THE SANTA BARBARA AND SANTA CRUZ BASINS FRIDAY AND SATURDAY AFTERNOON. OTHERWISE A GALE TO STORM FORCE WIND FETCH IN THE VICINITY NEW ZEALAND SOUTH ISLAND THIS MORNING WILL GRADUALLY SHIFT EAST. WHILE THE STORM SYSTEM SHIFTS EAST THE WINDS ARE EXPECTED TO WEAKEN AND GALE FORCE WINDS WILL PREVAIL THROUGH WEDNESDAY MORNING. THE FETCH IS ORIENTED 200-220 DEGREES RELATIVE TO VENTURA COUNTY. THE SWELLS WILL BEGIN TO ARRIVE MONDAY MORNING AND BUILD THROUGH TUESDAY. && .LOX WATCHES/WARNINGS/ADVISORIES... NONE && $$ PUBLIC...MW AVIATION...SIRARD MARINE...30 WWW.WEATHER.GOV/LOSANGELES

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