FXUS65 KVEF 070615 AAB
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
1015 PM PST SUN DEC 6 2009

SYNOPSIS...A COLD LOW PRESSURE SYSTEM WILL MOVE INTO NORTHERN 
CALIFORNIA MONDAY. WIDESPREAD VALLEY RAIN...MOUNTAIN SNOW..AND GUSTY 
WINDS WILL DEVELOP ACROSS MUCH OF THE AREA ON MONDAY THROUGH MONDAY 
NIGHT. A SERIES OF STORMS WILL IMPACT THE REGION THROUGH THE 
REMAINDER OF THE WEEK.
&&

.UPDATE...LOCALLY STRONG DOWNSLOPE WINDS IN THE LEE OF THE SOUTHERN 
SIERRA HAVE DECREASED SUBSTANTIALLY OVER THE PAST 3 HOURS. WINDS IN 
THE OWENS VALLEY AND DEATH VALLEY NATL. PARK HAVE EASED UP AS WELL. 
HIGH WIND WARNING HAS BEEN ALLOWED TO EXPIRE...WHILE WIND ADVISORY 
HAS BEEN CANCELLED. MODELS STILL SHOWING INGREDIENTS COMING TOGETHER 
TOMORROW AFTERNOON AND EVENING FOR WIDESPREAD RAIN AND MOUNTAIN 
SNOW. IF ANYTHING...MODELS ARE TAKING BRUNT OF HIGHER QPF VALUES 
ACROSS CLARK...SAN BERNARDINO AND MOHAVE COUNTIES WITH LIGHTER 
AMOUNTS FROM BISHOP EAST TO PIOCHE. TROUGH IS PROGRESSIVE WITH 
MOISTURE/DYNAMICS QUICKLY SPREADING EAST INTO ARIZONA BETWEEN 10 PM 
MONDAY EVENING AND 1 AM TUESDAY MORNING. NAM BURF SOUNDING SHOWS 
SNOW LEVELS FALLING TO THE VALLEY FLOORS AROUND THIS TIME SO CAN NOT 
RULE OUT SEE SOME LIGHT FLURRIES AROUND LAS VEGAS. ANOTHER COLD 
NIGHT IN STORE TUESDAY NIGHT AS WE AWAIT THE ARRIVAL OF OUR NEXT 
SYSTEM
&&

.AVIATION...FOR MCCARRAN...SIGNIFICANT CHANGE IN THE WEATHER IS 
EXPECTED FOR MONDAY. CLOUD COVER WILL INCREASE TONIGHT AHEAD OF A 
STRONG STORM DROPPING IN FROM THE NORTHWEST. BY MIDDAY MONDAY EXPECT 
THE CEILINGS TO BE BELOW 5000 FT AND CONTINUE TO LOWER THROUGH THE 
END OF THE 06Z TAF. CEILINGS COULD GO BELOW 3000 FT MONDAY EVENING 
WITH WIDE SPREAD RAIN AROUND AND AT KLAS. THE LOCAL MOUNTAINS WILL 
BE OBSCURED AND EXPERIENCE SNOWFALL DOWN TO ABOUT THE 3500 FT LEVEL 
MONDAY AFTERNOON. CEILINGS AND VISIBILITY WILL QUICKLY IMPROVE AFTER 
06Z TUESDAY.  

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...AN APPROACHING STORM SYSTEM FROM NORTHERN CALIFORNIA 
WILL BRING WINTRY WEATHER TO AREA MONDAY. CEILINGS WILL DECREASE TO 
THE 3000-5500 AGL FT LEVEL FROM THE WEST TO EAST AND BY 06Z TUESDAY 
EVENING EXPECT WIDESPREAD CEILINGS BELOW 3000 FT AND MOUNTAIN 
OBSCURATIONS. RAIN AND SNOW WILL BE WIDESPREAD AS WELL BY MONDAY 
AFTERNOON WITH CEILINGS AND VISIBILITIES IFR IN MANY LOCATIONS. 
CONDITIONS WILL IMPROVE FROM WEST TO EAST EARLY TUESDAY MORNING. 
&&

...PREV DISCUSSION...302 PM PST SUN DEC 6 2009...

.SHORT TERM...AT THIS TIME THE STRONG LOW PRESSURE SYSTEM THAT WILL 
BE THE MAIN FEATURE FOR WEATHER DURING THE NEXT 36 HOURS IS CENTERED 
OVER THE PACIFIC NORTHWEST. SOUTHWEST WINDS AHEAD OF THE FRONT WILL 
BE BREEZY ACROSS THE FORECAST AREA...WITH SOME LOCATIONS 
EXPERIENCING STRONG GUSTY WINDS. A WIND ADVISORY IS IN PLACE FOR THE 
WESTERN MOJAVE DESERT...DEATH VALLEY NATIONAL PARK...AND THE 
SOUTHERN NEVADA MOUNTAINS FROM MONDAY AT 00Z TO 12Z. A HIGH WIND 
WARNING IS IN PLACE FOR STRONG RIDGETOP WINDS ACROSS THE SOUTHERN 
SIERRA NEVADA FROM 18Z SUNDAY TO 06Z MONDAY. WINDS ABOVE 4000 FEET 
ARE EXPECTED TO BE THE STRONGEST WITH LOCATIONS ALONG THE SIERRA 
CREST EXPERIENCING WINDS AS STRONG AS 80 MPH. GUSTY WINDS WILL BEGIN 
TO SUBSIDE ACROSS THE HIGHER TERRAIN AND MOJAVE DESERT AS 
PRECIPITATION MOVES INTO THE AREA. THE LOW PRESSURE SYSTEM WILL PULL 
IN MOISTURE FROM THE PACIFIC OVER SOUTHERN CALIFORNIA AND SOUTHERN 
NEVADA...WHICH WILL INITIATE PRECIPITATION FROM WEST TO EAST. 
ALTHOUGH WIDESPREAD PRECIPITATION IS EXPECTED FROM MONDAY MORNING 
THROUGH EARLY TUESDAY...THE BEST TIME PERIOD FOR SIGNIFICANT RAIN 
AND SNOW WILL BE 21Z MONDAY TO 06Z TUESDAY. ELEVATIONS BELOW 3500 
FEET CAN EXPECT MOSTLY RAIN ON MONDAY AND AS SNOW LEVELS LOWER TO 
AROUND 2500 FEET OVERNIGHT...SOME LOCATIONS COULD EXPERIENCE A 
RAIN/SNOW MIX OR LIGHT SNOW SHOWERS. MOST LOCATIONS ABOVE 5000 FEET 
CAN EXPECT TO SEE SIGNIFICANT ACCUMULATIONS MONDAY NIGHT. THE WINTER 
STORM WATCH HAS BEEN UPGRADED TO A WINTER STORM WARNING FOR MOST OF 
THE FORECAST AREA THAT HAS TERRAIN ABOVE 4000 FEET. TUESDAY THE 
STORM SYSTEM MOVES TO THE EAST...LEAVING THE CHANCES FOR RAIN AND 
SNOW CONFINED TO MAINLY MOHAVE COUNTY. DRY NORTHWEST FLOW COMES IN 
BEHIND THE STORM SYSTEM LEAVING THE AREA UNDER MOSTLY CLEAR SKIES. 

.LONG TERM...THE START OF THE EXTENDED ON WEDNESDAY WILL SEE A BRIEF 
REPRIEVE FROM THE ACTIVE WEATHER PATTERN AS A SHORT WAVE RIDGE SETS 
UP OVER THE AREA. DECENT MODEL AGREEMENT ON HAVING A PACIFIC 
WAVE MOVE THROUGH THURSDAY TO EARLY FRIDAY. BEING A SMALL WAVE FROM 
THE PACIFIC MOST OF THE MOISTURE/QPF WILL BE DEPOSITED IN THE SIERRA 
BUT WITH ENOUGH TO KEEP THE CLOUD COVER OVER THE AREA AND FOR 
SOME VERY LIGHT PRECIPITATION AMOUNTS DOWN STREAM. SNOW LEVELS WILL 
BE HIGH ENOUGH TO KEEP THE PRECIPITATION LIQUID IN THE VALLEYS. 
ASIDE FORM THE SIERRA SNOW AMOUNTS SHOULD BE LIGHT AS WELL.  

ANOTHER WAVE IS FORECAST TO COME THROUGH ON SATURDAY. MODELS DIFFER 
IN STRENGTH AND DEPTH OF THIS ONE BUT ALL AGREE MOST OF THE ACTIVITY 
WILL BE IN THE NORTH PART OF THE CWA. THIS ONE I HAVE LOWER 
CONFIDENCE IN DUE TO IT BEING TOWARDS THE END OF THE EXTENDED AND 
ITS FORECASTED SHALLOW NATURE. AS WITH THE PREVIOUS SYSTEM ON 
THURSDAY/FRIDAY THIS ONE WILL HAVE SNOW LEVELS ALSO HIGH ENOUGH TO 
KEEP ANY SNOW IN THE HIGHER ELEVATIONS AND PRECIPITATION TOTALS LOW.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...WIND ADVISORY UNTIL 4 AM PST MONDAY FOR NVZ018-019.
     WINTER STORM WARNING FROM 10 AM MONDAY TO 4 AM PST TUESDAY FOR 
     NVZ014-015-018-019.
AZ...WINTER STORM WARNING FROM 11 AM MONDAY TO 5 AM MST TUESDAY FOR 
     AZZ001-003.
CA...WIND ADVISORY UNTIL 4 AM PST MONDAY FOR CAZ523.
     WINTER STORM WARNING FROM 10 AM MONDAY TO 4 AM PST TUESDAY FOR 
     CAZ522-524.
     WINTER STORM WARNING FROM 4 AM TO 10 PM PST MONDAY FOR CAZ519-
     521.
     HIGH WIND WARNING UNTIL 10 PM PST THIS EVENING FOR CAZ519.
&&

$$

PIERCE/LINDAMAN/JACQUES

HTTP://WEATHER.GOV/LASVEGAS