FXUS65 KVEF 120406
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
806 PM PST FRI DEC 11 2009

.SYNOPSIS...A WEAK DISTURBANCE WILL BRING SOME LIGHT RAIN AND SNOW 
TO THE AREA TONIGHT AND SATURDAY. A STRONGER LOW PRESSURE SYSTEM 
WILL BRING WIDESPREAD RAIN AND SNOW TO THE REGION SATURDAY NIGHT 
INTO SUNDAY WITH HEAVY SNOW LIKELY IN THE MOUNTAINS. DRY CONDITIONS 
AND A WARMING TREND CAN BE EXPECTED AS HIGH PRESSURE BUILDS IN 
MONDAY AND TUESDAY.
&&

.UPDATE...SATELLITE LOOP SHOWS THE WEAK FIRST IMPULSE OVER CLARK AND 
NORTHERN SAN BERNARDINO COUNTIES AS OF 8 PM. RADAR RETURNS ARE QUITE 
WEAK...AND GAGE AND SPOTTER REPORTS CONFIRM ONLY VERY LIGHT RAIN AND 
SNOW ASSOCIATED WITH THIS IMPULSE. THE MAIN BANG IS STILL ON TRACK 
FOR SATURDAY NIGHT AND SUNDAY MORNING...AND THIS IS WELL REFLECTED 
IN THE GOING FORECAST. NO UPDATE NEEDED AT THIS TIME.
&&

.PREV DISCUSSION...
340 PM PST FRI DEC 11 2009

.SHORT TERM...A WEAKENING DISTURBANCE WILL MOVE ACROSS THE AREA 
TONIGHT AND EARLY SATURDAY BRINGING SOME LIGHT RAIN AND SNOW WITH A 
BIT OF A BREAK IN THE ACTION SATURDAY AFTERNOON. SNOWFALL 
ACCUMULATIONS UP TO 3 INCHES COULD FALL IN THE MOUNTAINS ACROSS THE 
NORTHERN ZONES AND THE CLARK COUNTY MOUNTAINS. EVEN THOUGH 
PRECIPITATION CHANCES WILL DIMINISH BEHIND THIS DISTURBANCE LATE 
SATURDAY MORNING AND SATURDAY AFTERNOON...THERE WILL STILL BE PLENTY 
OF MOISTURE LINGERING FOR MOSTLY CLOUDY SKIES TO PERSIST. THE NEXT 
TROUGH WHICH WILL BE QUITE A BIT STRONGER WILL SPREAD WIDESPREAD 
RAIN AND SNOW ACROSS THE FORECAST AREA SATURDAY NIGHT INTO SUNDAY. 
WENT WITH A WINTER STORM WARNING ACROSS THE NORTHERN MOUNTAINS AND 
THE MOUNTAINS OF CLARK COUNTY SATURDAY NIGHT WITH THE WARNING 
CONTINUING UNTIL 18Z SUNDAY FOR THE CLARK COUNTY MOUNTAINS AND 
LINCOLN COUNTY. SNOW LEVELS WILL GENERALLY BE AROUND 5000 FEET WITH 
THIS STORM AND SNOWFALL IN THE WARNING AREA WILL BE AROUND A FOOT IN 
MOST AREAS WITH UP TO 2 FEET IN THE HIGHER ELEVATIONS OF THE SIERRA. 
PRECIPITATION WILL BE DECREASING FROM WEST TO EAST SUNDAY AND A 
GENERALLY DRY NORTHWEST FLOW IS EXPECTED SUNDAY NIGHT. TEMPERATURES 
WILL REMAIN A LITTLE BELOW NORMAL SATURDAY AND SUNDAY WITH THE 
EXTENSIVE CLOUD COVER AND PRECIPITATION. 

.LONG TERM...THE UNSETTLED WEATHER WILL BE ABSENT FROM THE REGION AS 
HIGH PRESSURE BEGINS TO BUILD IN MONDAY AFTERNOON. RIDGING WILL BE 
THE DOMINANT FEATURE FOR THE EXTENDED. UNDER THE RIDGING...THE AREA 
WILL HAVE RELATIVELY QUIET CONDITIONS...INCLUDING LITTLE TO NO WIND 
...WARMER TEMPERATURES...AND PARTLY CLOUDY SKIES. TEMPERATURES 
OVERNIGHT WILL STILL REMAIN SEASONABLY CHILLY ALTHOUGH HIGH 
TEMPERATURES COULD REACH INTO THE UPPER 50S IN THE LAS VEGAS VALLEY. 
THURSDAY AFTERNOON THE ECMWF AND A COUPLE OF GFS ENSEMBLE MEMBERS 
SHOW A DISTURBANCE MOVING ACROSS THE REGION TO THE NORTH OF THE 
FORECAST AREA. SLIGHT CHANCES OF PRECIPITATION TO THE NORTHERNMOST 
PORTION OF THE CWA ARE POSSIBLE.

.AVIATION...FOR MCCARRAN...WINDS WILL BE LIGHT AND VARIABLE THROUGH 
TONIGHT AND SATURDAY. MAIN IMPACT FOR THE REST OF THE AFTERNOON INTO 
TONIGHT WILL BE CEILINGS. OVERCAST AND BROKEN CEILINGS ARE EXPECTED 
THROUGHOUT THE PERIOD...WITH LITTLE CHANCE FOR SCATTERED CONDITIONS. 
RAIN SHOULD HOLD OFF UNTIL LATE TONIGHT...WITH MOST SHOWERS 
REMAINING TO THE WEST AND NORTH OF THE AIRPORT. SCATTERED SHOWERS 
EXPECTED AROUND 08Z SATURDAY AND THE CEILINGS WILL DROP WITH THE 
RAIN TO BETWEEN 3K AND 5K FEET. PRECIPITATION SHOULD FALL AS MOSTLY 
RAIN...BUT THERE IS A CHANCE FOR A RAIN/SNOW MIX AT TIMES. THE 
MOUNTAINS WILL REMAIN OBSCURED THROUGH SUNDAY AFTERNOON. 

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...MAINLY LIGHT WINDS THROUGH TONIGHT AND SATURDAY. 
CEILINGS IN MOST LOCATIONS WILL REMAIN BETWEEN 5K AND 8K FEET WITH 
SOME DROPPING TO AROUND 3K FEET WITH PRECIPITATION. PRECIP WILL 
SPREAD EAST BETWEEN 06Z-12Z SATURDAY AND SNOW LEVELS WILL REMAIN 
ABOVE 3500 FEET ACROSS THE SOUTHWEST. KDRA AND KBIH WILL HAVE A MIX 
OF SNOW AND RAIN...BUT BOTH LOCATIONS COULD HAVE MOSTLY SNOW. SNOW 
WILL DECREASE VISIBILITIES DOWN TO 1 TO 2 MILES AT TIMES AND CAUSE 
CEILINGS TO DROP DOWN TO AROUND 3K FEET. THE STORM WILL LEAVE THE 
AREA BY SUNDAY EVENING.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...WINTER STORM WARNING FROM 4 PM SATURDAY TO 10 AM PST SUNDAY FOR 
     NVZ015-018-019.
     WINTER STORM WARNING FROM 4 PM SATURDAY TO 4 AM PST SUNDAY FOR 
     NVZ014.
AZ...NONE.
CA...WINTER STORM WARNING FROM 4 PM SATURDAY TO 4 AM PST SUNDAY FOR 
     CAZ519-521-522.
&&

$$

MORGAN/HARRISON/LINDAMAN

HTTP://WEATHER.GOV/LASVEGAS