####018003395#### FXUS63 KFGF 132015 AFDFGF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 215 PM CST FRI FEB 13 2009 .SHORT TERM... THE EARLY CHALLENGE WILL BE TIMING OUT THE CLOUDS AND LIGHT FLURRIES ACROSS THE NORTHERN AND EASTERN FA...THEN IT WILL BE TEMPS AND THE NEXT CHANCE OF LIGHT SNOW FOR SUN NIGHT/MON. MODELS REMAIN PRETTY CONSISTENT WITH THE SUN NIGHT/MON SYSTEM SO WILL PRETTY MUCH STICK WITH FORECAST CONTINUITY FOR THE SHORT TERM. TONIGHT...STILL HAVE SOME AREAS OF LOWER CLOUDS AND VERY LIGHT SNOW OR FLURRIES...MAINLY IN THE NORTH AND NORTHEAST FA. HARD TO PICK ANYTHING DISTINCT OUT IN THE WATER VAPOR IMAGERY...BUT MODELS SHOW A FAIRLY DECENT VORTICITY MAX OVER THE NORTHERN FA NOW. 11-3.9 MICRON SATELLITE IMAGERY SHOWS THESE LOWER CLOUDS ARE NOT ONE BIG SOLID AREA...BUT DISTINCTIVE AREAS. WITH SEVERAL SITES STILL REPORTING SOME VERY LIGHT SNOW...WILL EXTEND THE MENTION OF FLURRIES OVER THE NORTH/NE INTO THE EVENING. NEXT SHIFT CAN WATCH AND SEE IF THESE GO AWAY ANY SOONER. ALL SAID...THESE ARE VERY MINIMAL AND WILL NOT SLOW ANYONE DOWN. THE CLOUDS WILL PLAY SOME HAVOC WITH THE LOW TEMP FORECAST TONIGHT...IF THEY STAY AROUND THEY WILL HOLD TEMPS UP. WILL GO WITH A DIMINISHING TREND TO THE CLOUDS OVER THE NW/NORTH FA AND GO WITH COLDEST MINS THERE (THEY ARE ALSO CLOSEST TO THE SFC RIDGE AXIS). SINCE THIS AREA DID NOT REALLY GET ABOVE THE SINGLE DIGITS TODAY...IT SHOULD BE EASY TO GET TO BELOW ZERO BY SAT MORNING. COULD EVEN BE COLDER IF IT CLEARS SOONER. SAT-MON...SFC HIGH PRESSURE LOOKS TO HOLD OVER THE FA FOR SAT INTO SUN. THEREFORE...NOT EXPECTING MUCH MIXING (WINDS)...BUT SHOULD HAVE A FAIR AMOUNT OF SUN. STILL A GOOD AMOUNT OF SNOW COVER...SO TEMPS WILL NOT WARM TOO MUCH. NEXT WARM ADVECTION/BAROCLINIC ZONE SNOW ANTICIPATED FOR SUN NIGHT. UPPER WAVE THEN SWINGS THRU BY MON HELPING TO ENHANCE A LITTLE LIGHT SNOW. AGAIN...SNOW AMOUNTS LOOK TO REMAIN PRETTY MEAGER. MODELS STILL STICKING TO THEIR GUNS... WITH THE ECMWF/UKMET SHOWING THE SNOW ALONG OR NORTH OF THE CANADIAN BORDER AND THE 12Z GFS/NAM SHOWING THE SNOW MAINLY NORTH OF THE SOUTH DAKOTA LINE. FORECAST HAS BEEN CARRYING SOME LOW CHANCES FOR SNOW...WHICH STILL LOOKS GOOD WITH MODEL DISPARITIES. .LONG TERM [TUE-FRI]... CURRENT MODELS SHOWING FA UNDER NORTHERLY FLOW WITH AN AREA OF HIGH PRESSURE OVER MANITOBA...ALLOWING COLD AND DRY AIR TO DOMINATE THE NORTH HALF OF THE AREA. AN UPPER LEVEL LOW OVER WESTERN ONTARIO WILL KICK OFF A SHORT WAVE WHICH SHOULD MOVE ACROSS EARLY IN THE PERIOD...PROVIDING A SLIGHT CHANCE FOR SOME SNOWFALL. AFTER THAT...THE HIGH PRESSURE RIDGE ACROSS THE AREA WILL KEEP THINGS DRY. MODELS HAVE NOT BEEN VERY CONSISTENT ON PLACEMENT OF THE CENTER OF THE HIGH...WITH THE 12Z ECMWF BEING FURTHER WEST THAN THE 00Z...BUT THE POTENTIAL IS THERE FOR A NIGHT WITH TEMPS BACK IN THE DOUBLE DIGITS BELOW ZERO IF THE HIGH SETS UP RIGHT OVER THE AREA. && .AVIATION... WEAK WAVE MOVING THROUGH FA WILL GENERATE SOME SNOW SHOWERS AT GFK..TVF...AND BJI THROUGH MID EVENING. MVFR CIGS WILL ACCOMPANY THE SHOWERS. CONDS SHOULD IMPROVE AND CIGS SCATTER OUT BY 03Z...WITH VFR CONDS FROM 03Z TO AT LEAST 18Z TOMORROW. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GODON/SPEICHER ####018006850#### FXUS66 KLOX 132016 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 1215 PM PST FRI FEB 13 2009 NEW AVIATION DISCUSSION .MORNING UPDATE...UPDATED THE LA COUNTY FORECAST TO INCLUDE SOME VERY ISOLATED SHOWERS THERE THIS MORNING, OTHERWISE THE MAIN RAIN BAND IS STILL TO THE WEST OVER SBA COUNTY WITH THE COLD FRONT ITSELF PASSING THROUGH SBP AT 8 AM. A FEW THUNDERSTORMS HAVE DEVELOPED ALONG THE FRONTAL BOUNDARY THIS MORNING WITH SOME SMALL HAIL REPORTED. NO BIG CHANGES TO THINKING AND THE REMAINDER OF THE FORECAST REMAINS IN TACT FOR TODAY AND TONIGHT. THE FRONT MAY BE MOVING A BIT FAST TO GENERATE WARNING LEVEL SNOW AMOUNTS BUT I'M NOT GOING TO SQUABBLE WITH THOSE MINOR DETAILS AT THIS POINT. UPDATE ON THE WEEKEND STORM. MODELS HAVE INDEED DELAYED THE ARRIVAL CONSIDERABLY. KUDOS TO THE NAM-WRF WHICH HAS BEEN INDICATING THIS SINCE WEDNESDAY. IT NOW APPEARS LA COUNTY WON'T SEE ANY SIGNIFICANT RAIN OR SNOW UNTIL MONDAY. STAY TUNED ON THIS ONE AS I EXPECT FURTHER TIMING ADJUSTMENTS OVER THE NEXT SEVERAL MODEL RUNS. ...REMAINDER FROM PREVIOUS DISCUSSION... .SHORT TERM (TODAY-SUNDAY)...TODAYS FORECAST SEEMS TO BE ON TRACK AS FAIRLY VIGOROUS AND RELATIVELY FAST MOVING COLD FRONT WILL BEGIN TO APPROACH THE CENTRAL COAST THIS MORNING AND CONTINUE TO MOVE SOUTHWARD ACROSS SANTA BARBARA COUNTY BY MID MORNING...WHILE MOVING ACROSS VENTURA AND LOS ANGELES COUNTIES LATER THIS AFTERNOON. MOST AREAS WILL RECEIVE BETWEEN 3 TO 5 HOURS OF STEADY RAINFALL.THIS STORM WILL LIKELY PRODUCE BETWEEN ONE HALF TO ONE INCH OF RAIN IN COASTAL AND VALLEY LOCATIONS...WITH UP TO ONE AND ONE HALF INCHES IN THE FOOTHILLS AND LOWER MOUNTAINS. LATEST 850 MB WIND PROFILE LOOKS FAVORABLE FOR LOCALLY HIGHER AMOUNTS WITH PLUS 2 INCHES ACROSS PORTIONS OF THE SANTA YNEZ RANGE AND ALSO THE SAN GABRIEL MOUNTAIN RANGE. WHILE THE FRONT MOVES DOWN THE COAST TODAY...A FAVORABLE 120 KT JET BEGINS TO DIVE DOWN ACROSS THE CENTRAL COAST INTO THE FORECAST AREA WITH THE LEFT FRONT QUADRANT OVER THE AREA LATE THIS MORNING AND AFTERNOON. THIS WILL HELP CREATE GOOD DIVERGENCE ALOFT AND WITH GOOD PVA THERE COULD BE SOME ISOLATED THUNDERSTORMS ACROSS THE FORECAST AREA...ESPECIALLY S OF POINT CONCEPTION. SOME OF THESE THUNDERSTORMS WILL PRODUCE SMALL HAIL AND GUSTY WINDS. A WINTER STORM WARNING HAS BEEN ISSUED FOR THE MOUNTAINS OF LOS ANGELES AND VENTURA COUNTY VALID FROM NOON TODAY THROUGH LATE TONIGHT. TOTAL SNOW ACCUMULATIONS SHOULD BE BETWEEN 8 TO 12 INCHES FOR AREAS ABOVE 4500 FT. THE SNOW LEVEL IS GENERALLY EXPECTED TO RANGE BETWEEN 3500 AND 4000 FEET WITH THIS SYSTEM...BUT COULD FALL AS LOW AS 3000 FEET NEAR HEAVIER SHOWERS OR THUNDERSTORMS. THE LOW SNOW LEVELS WILL LIKELY IMPACT THE INTERSTATE 5 CORRIDOR NEAR THE GRAPEVINE...AND POSSIBLY HIGHER PORTIONS OF HIGHWAY 14 THROUGH THE SOLEDAD PASS. A WINTER WEATHER ADVISORY HAS ALSO BEEN ISSUED FOR THE SANTA BARBARA COUNTY MOUNTAINS FOR THIS MORNING THROUGH TONIGHT AS WELL WITH EXPECTED SNOW ACCUMULATIONS OF 5 TO 10 INCHES. THE PRECIPITATION SHOULD BEGIN TO MOVE OUT OF THE AREA LATE TONIGHT WITH A FEW LINGERING SHOWERS ACROSS THE EASTERN LA COUNTY AND THE NRN SLOPES OF THE VENTURA COUNTY AND NORTHWESTERN LA COUNTY MOUNTAINS WITH SOME ADDITIONAL SNOW FLURRIES EARLY SAT. SKIES SHOULD REMAIN PARTLY TO MOSTLY CLOUDY ON SATURDAY WITH LINGERING MOISTURE ACROSS MUCH OF THE FORECAST AREA. THERE COULD BE A FEW SHOWERS...ESPECIALLY ACROSS THE FOOTHILLS AND MOUNTAINS...BUT SHOULD BE THE CALM BEFORE THE NEXT SIGNIFICANT STORM. A COLD AND VIGOROUS UPPER LVL LOW WILL SET UP OFF THE COAST OF NRN CAL/ORE BORDER ON SUN. AT THE LOWER LEVELS...AN IMPRESSIVE SURFACE LOW DEVELOPS WHICH WILL STRENGTHEN THE SOUTHERLY WINDS AHEAD OF THE NEXT FRONT THAT MOVES INTO THE AREA. ALL THREE MODELS...GFS/NAM-WRF/ECMWF HAVE SLOWED THE STORM CONSIDERABLY. THE FORWARD PROGRESSION OF THIS STORM SYSTEM HAS LIKELY STALLED DUE TO THE STRENGTH OF THE SOUTHERLY WINDS THAT DEVELOPED WITH THIS STRONG SFC LOW. IT NOW APPEARS THAT THE BULK OF THE PRECIP WILL BEGIN TO REACH SAN LUIS OBISPO COUNTY BY SUNDAY AFTERNOON AND SLOWLY PROGRESS TO THE SOUTH REACHING LOS ANGELES COUNTY BY SUNDAY EVENING AND PERSISTING THROUGH TUES. ALTHOUGH IT IS STILL EARLY...THE POTENTIAL EXISTS FOR 1 TO 3 INCHES ACROSS COASTS AND VALLEYS...WITH 2 TO 5 INCHES FOOTHILLS AND MOUNTAINS...WITH LOCALLY HIGHER AMOUNTS IN THE LOWER SOUTH FACING FOOTHILLS. READ THE LATEST SPECIAL WEATHER STATEMENT FOR MORE DETAILS ON THESE UPCOMING STORMS. GIVEN THE RECENT RAINS AND SATURATED SOILS...A STORM SYSTEM OF THIS MAGNITUDE WOULD BRING A RISK OF FLASH FLOODING...POSSIBLY EVEN TO NON BURN AREAS. THIS SITUATION WILL HAVE TO BE MONITORED CLOSELY OVER THE NEXT FEW DAYS. .LONG TERM...(MON-THU) BOTH GFS/AND ECMWF INDICATE THE BULK OF THE HEAVY RAIN WILL NOW FOCUS ON MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE FORECAST AREA. ESPECIALLY LOS ANGELES...VENTURA AND SANTA BARBRA COUNTIES. THE GFS ROTATES ANOTHER PIECE OF ENERGY ACROSS THE AREA ON WED FROM THE WEST WHICH WOULD LIKELY RAISE SNOW LEVELS...WHILE THE EURO PARKS A LOW FARTHER OFF THE COAST KEEPING MOST PRECIP OFF THE COAST. MODELS BEGIN TO DIVERGE A BIT ON WED AND THU...BUT THE MAIN TROUGHINESS AND THE POTENTIAL FOR CUT-OFF LOWS TO AFFECT THE AREA REMAIN THROUGH MOST OF NEXT WEEK. EXPECT LOWER THAN NORMAL TEMPS AND PERIODS OF RAIN THROUGH AT LEAST THU. && .AVIATION...13/2015Z. A COLD FRONT WILL PUSH THROUGH THE FORECAST AREA THIS AFTERNOON...BRINGING A NARROW BAND OF MODERATE TO HEAVY RAIN...FOLLOWED BY A FEW HOURS OF SCATTERED SHOWERS. SKIES WILL CLEAR ACROSS THE FORECAST AREA BEGINNING LATE THIS AFTERNOON IN THE NORTH AND BY THIS EVENING IN THE SOUTHERN PORTIONS. SKIES WILL BE MOSTLY CLEAR LATE TONIGHT AND SATURDAY...ASIDE FROM LOCALLY DENSE MORNING FOG IN SOME OF THE VALLEYS. KLAX AND KBUR...A COLD FRONT WILL SWEEP THROUGH THIS AFTERNOON SWITCHING THE WIND DIRECTION FROM SOUTHEAST TO WEST-SOUTHWEST...ALTHOUGH A PRE-FRONTAL LINE OF HEAVY RAIN MAY SIMULATE THE FRONT...SWITCHING THE WINDS AROUND TO THE SOUTHWEST PREMATURELY. THE WINDS COULD SWITCH BACK TO THE SOUTHEAST AGAIN BEFORE THE ACTUAL FRONT MOVES THROUGH BY LATE AFTERNOON OR EARLY THIS EVENING. && .LOX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING (SEE LAXWSWLOX). WINTER WEATHER ADVISORY (SEE LAXWSWLOX). SMALL CRAFT ADVISORY (SEE LAXMWWLOX). SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX). && $$ PUBLIC...WOFFORD/KAPLAN AVIATION...SWEET WWW.WEATHER.GOV/LOSANGELES