FXUS65 KVEF 040411
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
811 PM PST THU DEC 3 2009

.SYNOPSIS...HIGH PRESSURE OVER THE AREA WILL KEEP DRY WEATHER AND 
SUBFREEZING MINIMUM TEMPERATURES THROUGH SATURDAY. HIGH PRESSURE 
WILL BREAKDOWN THIS WEEKEND...WHICH WILL ALLOW FOR A SERIES OF 
STRONG PACIFIC STORMS TO IMPACT THE AREA. COOLER THAN NORMAL 
TEMPERATURES WILL PERSIST THROUGH THE WEEKEND AND INTO NEXT WEEK.  
&&

.UPDATE...WINDS DIMINISHED EARLIER THAN EXPECTED. CANCELLED RED
FLAG WARNING AND WIND ADVISORY ALONG THE COLORADO RIVER. WILL
UPDATE FORECAST FOR LESS WIND.
&&

.PREVIOUS DISCUSSION...230 PM PST THU DEC 3...SHORT TERM...A WIND
ADVISORY HAS BEEN ISSUED FOR THE COLORADO RIVER VALLEY FOR STRONG
NORTH WINDS. WINDS HAVE PICKED UP ALONG THE COLORADO RIVER VALLEY
EARLY THIS AFTERNOON...WITH SOME SITES RECORDING GUSTS AROUND 35
MPH. EXPECT WINDS TO INCREASE THROUGH THE AFTERNOON AND INTO
TONIGHT...WITH THE PEAK WINDS OCCURRING AROUND MIDNIGHT. CLEAR
SKIES AND COLDER THAN NORMAL TEMPERATURES WILL PERSIST THROUGH THE
WEEKEND WITH HIGH PRESSURE BREAKING DOWN FRIDAY INTO SATURDAY. A
FREEZE WARNING IS IN EFFECT EARLY FRIDAY MORNING AND EARLY
SATURDAY MORNING FOR SUBFREEZING TEMPERATURES ACROSS THE MOJAVE
DESERT AND LAS VEGAS. EXPECT MINIMUM TEMPERATURES TO DROP BETWEEN
5 TO 10 DEGREES OVERNIGHT TONIGHT...WHILE TEMPERATURES ON SATURDAY
MORNING ARE EXPECTED EVEN COLDER. SATURDAY EVENING A SHORTWAVE
CARVES ITS WAY DOWN ACROSS THE EASTERN EDGE OF THE CWA...WHICH MAY
BRING A SLIGHT CHANCE OF SNOW TO LINCOLN COUNTY...BUT ONLY ECMWF
IS SHOWING THIS SOLUTION. MAIN IMPACT FOR THE REMAINDER OF THE CWA
ON SATURDAY WILL BE DECREASING TEMPERATURES AND AN INCREASE IN
WINDS IN SAN BERNARDINO COUNTY. NORTHWEST TO WEST FLOW WILL BE
OVER THE AREA ON SUNDAY WHEN ANOTHER SHORTWAVE HEADING SOUTH MAKES
ITS WAY TOWARDS THE CWA. ALONG WITH THIS SHORTWAVE COMES ANOTHER
ROUND OF WEST TO SOUTHWEST WINDS FOR SAN BERNARDINO COUNTY.

.LONG TERM...STILL SOME DIFFERENCES IN THE MODELS EARLY IN THE 
EXTENDED WITH REGARDS TO HOW FAR THE PACIFIC NORTHWEST LOW DROPS 
SOUTH. GFS...WHICH HAS BEEN THE MOST CONSISTENT MODEL...BRINGS THE 
LOW INTO NORTHERN CALIFORNIA MONDAY MORNING AND EVENTUALLY ACROSS 
NORTHERN NEVADA BEFORE OPENING AND SWINGING THE TROUGH INTO THE 
ROCKY MOUNTAIN STATES TUESDAY MORNING. ALTHOUGH THE GFS IS FORECAST 
TO PULL SOME PACIFIC MOISTURE INLAND...IT DOES NOT LOOK TO TAP INTO 
ANYTHING SIGNIFICANT. HOWEVER...A COLD FRONT PUSHING THROUGH THE 
REGION SHOULD BE STRONG ENOUGH TO WRING OUT ANY AVAILABLE MOISTURE. 
THE TIMING OF THE FRONT WILL BE THE BIGGEST CONCERN DUE TO THE 
SIGNIFICANT AMOUNT OF COLD AIR BEHIND THE FRONT. GFS BUFR SOUNDING 
FOR LAS VEGAS IS SHOWING A BIG DROP IN FREEZING LEVELS AND WET BULB 
ZERO LEVELS ABOUT 03Z-06Z MONDAY NIGHT. THIS COULD POTENTIALLY PUT 
MANY VALLEY LOCATIONS ABOVE 2000 FEET IN A BRIEF PERIOD OF RAIN SNOW 
MIX OR A BRIEF PERIOD OF ALL SNOW JUST AS THE FRONT PUSHES THROUGH. 
ACCUMULATIONS WOULD NOT BE EXPECTED IN THE VALLEYS...BUT HIGHER 
ELEVATIONS COULD SEE A FEW INCHES OF SNOW. COLD AIR ADVECTION 
EXPECTED ALL DAY TUESDAY AND ITS POSSIBLE THAT TEMPERATURES IN LAS 
VEGAS WILL REMAIN IN THE 40S FOR HIGHS. WE WILL SEE A BRIEF DRYING 
TREND WEDNESDAY AS A WEAK RIDGE MOVES OVER THE AREA. HOWEVER...THE 
MODELS ARE FORECASTING A SERIES OF STORMS TO AFFECT THE AREA 
BEGINNING THURSDAY AND CONTINUE THROUGH THE WEEKEND. 
&&

.AVIATION...FOR MCCARRAN...NORTHEAST WINDS 10-18 KNOTS ARE EXPECTED 
TO DIMINISH EARLY THIS EVENING TO AROUND 7-10 KNOTS AND DIMINISH 
FURTHER OVERNIGHT TO AROUND 5 KNOTS. WINDS ON FRIDAY ARE FORECAST TO 
REMAIN UNDER 6 KNOTS THROUGH THE DAY. SKIES WILL REMAIN MOSTLY CLEAR 
THOUGH FRIDAY. 

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...GUSTY NORTH WINDS DOWN THE COLORADO RIVER VALLEY ARE 
EXPECTED TO CONTINUE THROUGH 04Z THIS EVENING BEFORE DIMINISHING. 
WINDS GUSTING UP TO 35 KNOTS ARE EXPECTED. WINDS WILL DIMINISH TO 
AROUND 10-20 KNOTS AFTER 02Z AND THEN DIMINISH TO AROUND 7-10 KNOTS 
AFTER 06Z. NORTH WINDS FROM 6-9 KNOTS ARE EXPECTED ON FRIDAY. SKIES 
WILL REMAIN MOSTLY CLEAR. 

.FIRE WEATHER...LOCALLY GUSTY NORTH WINDS...ESPECIALLY DOWN THE 
COLORADO RIVER VALLEY...WILL USHER IN A VERY DRY AIRMASS TODAY. A 
RED FLAG WARNING IS IN EFFECT THROUGH MIDNIGHT FOR GUSTY NORTH WINDS 
AND LOW RELATIVE HUMIDITIES. MINIMUM RELATIVE HUMIDITY VALUES WILL 
DROP INTO THE LOW TEENS AND SINGLE DIGITS WITH MARGINAL RECOVERY 
TONIGHT. WINDS WILL CONTINUE TO INCREASE BETWEEN 25 AND 35 MPH WITH 
WIND GUSTS UP TO 45 MPH IN SOME LOCATIONS...WITH THE PEAK WINDS 
OCCURRING AROUND MIDNIGHT.
&&

&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM PST FRIDAY FOR 
     NVZ016-020-022.
     FREEZE WARNING FROM 10 PM FRIDAY TO 9 AM PST SATURDAY FOR NVZ016-
     020>022.
AZ...FREEZE WARNING FROM 11 PM FRIDAY TO 10 AM MST SATURDAY FOR 
     AZZ002-036.
CA...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM PST FRIDAY FOR 
     CAZ523-524.
     FREEZE WARNING FROM 10 PM FRIDAY TO 9 AM PST SATURDAY FOR 
     CAZ523>527.
&&

$$

HARRISON/LINDAMAN/GORELOW

HTTP://WEATHER.GOV/LASVEGAS