FXUS65 KVEF 260432
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
830 PM PST FRI DEC 25 2009

.SYNOPSIS...HIGH PRESSURE OVER THE SOUTHWEST STATES WILL GIVE WAY 
LATE SATURDAY TO A SERIES OF WEAK STORMS AFFECTING THE REGION SUNDAY 
THROUGH NEW YEARS DAY. THIS PATTERN WILL MAINLY BRING PERIODS OF 
CONSIDERABLE CLOUDINESS TO THE REGION AND POSSIBLY A FEW FLURRIES TO
THE HIGHER PEAKS.
&&

.UPDATE...VERY SIMILAR CONDITIONS TO LAST NIGHT. DUE TO LIGHT 
WINDS...LACK OF ANY CLOUD COVER...SOME COLD ADVECTION ALOFT OVER 
SOUTHERN NEVADA...I HAVE LOWERED TEMPS TONIGHT IN SOUTHERN NEVADA. 
TEMPERATURES HAVE ALREADY BEGUN TO DROP INTO THE UPPER 30S IN 
PORTIONS OF THE LAS VEGAS VALLEY. EXPECT LOWS NEAR FREEZING AT 
MCCARRAN AND FALLING INTO THE MID TO UPPER 20S IN LOCATIONS LIKE 
SUMMERLIN AND HENDERSON...WHILE MANY LOCATIONS ACROSS LINCOLN COUNTY 
WILL DIP INTO THE SINGLE DIGITS. A SHORTWAVE RIDGE WILL MOVE THROUGH 
THE AREA OVER THE NEXT 18 TO 24 HOURS. CLOUD COVER WILL INCREASE 
TOMORROW AFTERNOON AHEAD OF A WEAK IMPULSE OF ENERGY. 

.PREV DISCUSSION...A HIGHLY AMPLIFIED RIDGE SHIELDING THE WEST 
FROM ANY SIGNIFICANT WEATHER WILL BE UNDERCUT LATE SATURDAY BY 
ENERGY EJECTING FROM A BROAD EASTERN PACIFIC TROUGH. A SUBSTANTIAL 
PLUME OF MID AND HIGH LEVEL MOISTURE...CURRENTLY ALONG 130W...WILL 
BE PULLED ACROSS THE FORECAST AREA SATURDAY AFTERNOON THROUGH 
SUNDAY. NO SIGNIFICANT DIFFERENCES EXIST AMONG THE MODELS AND THE 
FORECAST IS BASED ON THE GFS SOLUTION. TIME-HEIGHT SECTIONS INDICATE 
SUFFICIENT MOISTURE FOR SOME LIGHT SNOW TO FALL ON THE HIGHEST PEAKS 
SATURDAY NIGHT AND EARLY SUNDAY BUT THE MAIN RESULT WILL BE FAIRLY 
DENSE CLOUD COVER. ADDITIONAL ENERGY ENTERING THE EASTERN PACIFIC 
TROUGH IS FORECAST TO DIG THE SYSTEM TOWARD BAJA. THIS WILL LEAVE A 
VERY WEAK TROUGH WITH MID LEVEL MOISTURE CROSSING THE REGION MONDAY 
FOR MORE CLOUDS BUT LITTLE PRECIPITATION EXCEPT POSSIBLY AGAIN ON 
THE HIGHEST PEAKS. A PERSISTENT NORTH/SOUTH SURFACE PRESSURE 
GRADIENT IS FORECAST TO HOLD ALONG THE SOUTHERN NEVADA/UTAH BORDER 
THROUGH MONDAY FOR CONTINUED BREEZES DOWN THE COLORADO RIVER 
VALLEY...THOUGH SPEEDS SHOULD BE DOWN A LITTLE FROM TODAY. HIGH 
TEMPERATURES WILL DROP A FEW DEGREES AND LOW TEMPERATURES SHOULD 
COME UP SLIGHTLY AS A RESULT OF THE CLOUDS.

.LONG TERM...SYSTEM ON TUESDAY STILL FORECAST TO TRACK SOUTH OF THE 
AREA WITH SOME POTENTIAL OF WRAP AROUND MOISTURE AFFECTING THE FAR 
SOUTHERN AREAS OF SAN BERNARDINO AND MOHAVE COUNTIES...ALTHOUGH 
CHANCES ARE LOOKING LESS LIKELY WITH EACH MODEL RUN. THE ECMWF AND 
TO A WEAKER EXTENT THE GFS IS SHOWING A SECOND PIECE OF ENERGY 
MOVING SOUTHEAST THROUGH NORTHERN NEVADA TUESDAY AFTERNOON AND 
NIGHT. THIS IS NOT EXPECTED TO BRING MUCH TO OUR CWA AND ONLY HAVE 
GHOST POPS MENTIONED ACROSS THE FAR NORTHERN ZONES. MODELS ARE 
INDICATING RIDGING DEVELOPING WEDNESDAY WHICH IS FORECAST TO REMAIN 
THROUGH THE REMAINDER OF THE WEEK. TEMPERATURES ARE FORECAST TO 
REMAIN AT OR SLIGHTLY BELOW NORMAL THROUGH NEXT WEEK.
&&

.AVIATION...FOR MCCARRAN...NO SIGNIFICANT WEATHER THROUGH SUNDAY 
WITH VARIABLE WINDS BECOMING NORTHEAST UNDER 8KTS EACH AFTERNOON AND 
LIGHT SOUTHWEST AT NIGHT. VARIABLE AMOUNTS OF HIGH CLOUDS EXPECTED 
THROUGH SATURDAY AFTERNOON WITH A BAND OF MID/LOW LEVEL CLOUDS 
MOVING ACROSS SOUTHERN NEVADA LATE SATURDAY NIGHT INTO SUNDAY.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...NORTH WINDS AT 10-15 KNOTS WILL CONTINUE DOWN THE 
COLORADO RIVER FOR MUCH OF THE NIGHT. NORTH WINDS ARE EXPECTED TO 
INCREASE ONCE AGAIN DOWN THE COLORADO RIVER SATURDAY AFTERNOON TO 
AROUND 15-20 KNOTS. ELSEWHERE WINDS WILL GENERALLY REMAIN UNDER 10 
KNOTS THROUGH SATURDAY. THERE WILL BE SOME INCREASING CLOUDS 
SATURDAY AFTERNOON WITH SLIGHT CHANCE OF SNOW OVER THE SIERRA WITH 
DRY CONDITIONS ELSEWHERE. 
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&

$$

CZYZYK/ADAIR/GORELOW

HTTP://WEATHER.GOV/LASVEGAS