Area Forecast Discussion
Issued by NWS Los Angeles, CA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS66 KLOX 200515 AAA AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 1015 PM PDT TUE AUG 19 2014 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK WITH ABOVE NORMAL TEMPERATURES. && .UPDATE... THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE. THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT. BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT. THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM- WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM- WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER POSSIBILITIES FOR THURSDAY. && .PREV DISCUSSION... SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND. LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST WITH LITTLE EFFECT ON TEMPERATURES. && .AVIATION...20/0515Z... OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT. OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE SITUATION CLOSELY. KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY. KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY. && .MARINE...19/900 PM. TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO- OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS. && .LOX WATCHES/WARNINGS/ADVISORIES... MARINE WEATHER STATEMENT (SEE LAXMWWLOX). && $$ PUBLIC...HALL/BOLDT AVIATION...GOMBERG MARINE...HALL SYNOPSIS...SETO/HALL WWW.WEATHER.GOV/LOSANGELES

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.