FXUS65 KVEF 101302 CCA
AFDVEF

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LAS VEGAS NV
459 AM PST THU DEC 10 2009

.SYNOPSIS...INCREASING MOISTURE WILL ACCOMPANY A WEAK PACIFIC
SYSTEM MOVING INLAND TONIGHT AND ACROSS THE REGION FRIDAY.
A STRONGER STORM AND ADDITIONAL MOISTURE WILL BRING WIDESPREAD 
PRECIPITATION TO MUCH OF THE REGION SATURDAY AND SUNDAY...WITH SNOW 
MAINLY CONFINED TO ELEVATIONS ABOVE 5000 FEET. HIGH PRESSURE WILL 
THEN DEVELOP OVER THE SOUTHWEST PROVIDING A DRY WEATHER PATTERN 
EARLY NEXT WEEK.
&&

.SHORT TERM...AN INITIAL SWATH OF MID AND HIGH LEVEL MOISTURE WAS 
PRECEDING A WEAK IMPULSE CURRENTLY MOVING FROM CENTRAL CALIFORNIA 
INTO CENTRAL NEVADA. THE MAIN FEATURES TO WATCH ARE A WEAK SHORTWAVE 
CURRENTLY NEAR 33N/135W AND...MORE SIGNIFICANTLY...A PACIFIC LOW 
SOUTH OF THE ALEUTIAN CHAIN. THESE WILL TAP A STREAM OF MOISTURE 
RIDING ALONG 30N AND EXTENDING BACK BEYOND THE DATELINE. THE FIRST 
SYSTEM WILL MOVE ACROSS THE REGION TONIGHT AND EARLY FRIDAY BRINGING 
A QUICK CHANCE OF LIGHT PRECIPITATION TO MUCH OF THE AREA. ANY 
MEASURABLE RAIN IN THE DESERTS SHOULD ONLY AMOUNT TO A FEW 
HUNDREDTHS. THE MORE SIGNIFICANT STORM WILL BRING DEEPER MOISTURE 
INTO THE SOUTHERNS SIERRA FRIDAY NIGHT THEN DIRECT IT INTO SOUTHERN 
NEVADA AND NORTHWEST ARIZONA SATURDAY AFTERNOON AND SATURDAY NIGHT. 
THE SYSTEM THEN MOVES INLAND AS A BROAD OPEN TROUGH SUNDAY WITH 
PRECIPITATION TAPERING OFF OVER THE AREA. THIS SYSTEM WILL NOT BE 
NEARLY AS COLD AS THE STORM EARLY THIS WEEK AND SNOW LEVELS WILL BE 
GENERALLY ABOVE 5000-6000 FEET. A WINTER STORM WATCH WAS ISSUED FOR 
THE SOUTHERN SIERRA/INYO COUNTY MOUNTAINS AND THE SOUTHERN NEVADA 
MOUNTAINS SATURDAY AND SUNDAY. TIME-HEIGHT SECTIONS ALSO INDICATES
SUBSTANTIAL LOW LEVEL MOISTURE...SURFACE TO 700 MB...IS FORECAST 
ACROSS SOUTHEAST CALIFORNIA AND SOUTHERN NEVADA SATURDAY WHILE MID 
LEVEL MOISTURE IS LIMITED. WEAKER DYNAMICS AND LESS OVERALL 
PRECIPITABLE WATER SHOULD RESULT IN LESS TOTAL RAINFALL...WITH 
AMOUNTS GENERALLY BETWEEN A QUARTER TO HALF AN INCH.

.LONG TERM...THE AFOREMENTIONED FINAL SYSTEM WILL DEPART THE AREA ON 
SUNDAY AFTERNOON...HOWEVER THE CHANCE OF PRECIPITATION WILL STILL 
EXIST ESPECIALLY ACROSS LINCOLN AND MOHAVE COUNTIES AND BACK TOWARDS 
THE SPRING MOUNTAINS. ADDITIONAL PRECIPITATION - THOUGH PERHAPS MORE 
"SHOWERY" IN NATURE - WILL BE POSSIBLE ACROSS THE EASTERN SOUTHERN 
SIERRA AS MOISTURE LINGERS AND ENERGY RIPPLES THROUGH THE ATMOSPHERE 
AROUND 18000 FEET. SNOW LEVELS WILL ALSO FALL AS COLDER AIR MOVES IN 
ON THE BACK SIDE OF THIS SYSTEM DROPPING TO AROUND 4000 FEET NORTH 
AND 5500-6000 FEET IN THE SOUTH. BY SUNDAY NIGHT DRY NORTHWEST FLOW 
SHOULD HELP TO END ANY OF THE PRECIPITATION. BASED ON THE CURRENT 
MODEL TIMING POPS LEFT IN THE GRIDS WERE LOWERED BUT ARE PROBABLY 
STILL OVERDONE ESPECIALLY IN THE WESTERN HALF OF THE AREA.

AFTER A WEEK OF COLD AND STORMIER WEATHER...BRIGHTER AND "WARMER" 
TIMES ARE AHEAD FOR THE AREA AS AN UPPER RIDGE SLIDES EASTWARD 
ACROSS THE SOUTHWEST U.S.. THIS WILL ALLOW FOR SOME WARMING WITH 
HIGHS CLOSER TO NORMAL...HOWEVER MIXING WILL BE WEAK SO HAVE GONE A 
LITTLE UNDER WHAT GUIDANCE WANTS TO WARM US TO. STILL THERE IS SOME 
CHANCE ONCE THE RIDGE AXIS HEADS EAST OF OUR AREA BY WEDNESDAY THAT 
WE MAY MIX A LITTLE BETTER AND HAVE THE CHANCE OF SEEING HIGH TEMPS 
A FEW DEGREES ABOVE NORMAL WHICH BY COMPARISON TO THIS WEEK WILL 
FEEL WARM. THE MAIN STORM TRACK WILL BE WELL NORTH OF THE AREA 
HOWEVER CLOUDS WILL STILL STREAM ACROSS NORTHERN AREAS AT TIMES. THE 
OPERATIONAL GFS AND DGEX ARE TRYING TO CUT SOME ENERGY OFF UNDER THE 
RIDGE...BUT WITH A LACK OF MOISTURE THIS SHOULD HAVE NO BIG IMPACT 
ANY ANYTHING OTHER THAN TEMPS. NIGHTTIME LOWS THOUGH LOOK TO BE A 
BIT CHILLY ESPECIALLY AT THE START OF THE WEEK. 
&&

.AVIATION...FOR MCCARRAN...LIGHT AND VARIABLE WINDS THROUGH TONIGHT 
WITH VARYING AMOUNTS OF CLOUD COVER AOA 25K FEET. A SERIES OF STORM 
SYSTEMS WILL BRING THE POSSIBILITY OF LOW CEILINGS AND RAIN TO THE 
AIRPORT STARTING FRIDAY NIGHT INTO SATURDAY MORNING AND EXIT BY 
SUNDAY AFTERNOON. THE MOST LIKELY TIME FOR RAIN IN THE VALLEY RIGHT 
NOW LOOKS TO BE FRIDAY AFTERNOON WITH A BETTER CHANCE ON SATURDAY 
AFTERNOON AND NIGHT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...LIGHT WINDS MAINLY FOLLOWING NORMAL DIURNAL DIRECTIONAL 
TRENDS THROUGH TONIGHT WITH VARIABLE AMOUNTS OF CLOUD COVER MAINLY 
ABA 20K FEET THOUGH CLOUD LAYERS AS LOW AS 7K-12K FEET ARE EXPECTED 
IN THE KBIH AREA. A SERIES OF SYSTEMS WILL IMPACT THE AREA STARTING 
FRIDAY AFTERNOON. MOST OF THE AREA WILL SEE TWO MAIN WINDOWS FOR 
PRECIPITATION AND LOWER CEILINGS - FROM FRIDAY AFTERNOON INTO EARLY 
SATURDAY MORNING AND FROM SATURDAY AFTERNOON INTO SATURDAY EVENING. 
THIS SYSTEM WILL MOVE OUT ON SUNDAY. GUSTY WINDS TO AROUND 25 KTS 
ARE ALSO POSSIBLE IN AREAS THAT FAVOR WEST TO SOUTHWEST WINDS THEN. 
MOUNTAIN OBSCURATIONS WILL BE LIKELY THROUGH THE PERIOD.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY 
     AFTERNOON FOR NVZ018-019.
AZ...NONE.
CA...WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH LATE SATURDAY 
     NIGHT FOR CAZ519-521-522.
&&

$$

ADAIR/STACHELSKI

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