FXUS65 KVEF 262242
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
242 PM PST THU NOV 26 2009

.SYNOPSIS...A PACIFIC LOW PRESSURE SYSTEM WILL MOVE INTO NORTHERN 
AND CENTRAL CALIFORNIA FRIDAY...BRINGING INCREASING HIGH CLOUDINESS 
AND SOME SOUTHERLY BREEZES. THIS LOW WILL THEN MOVE TO SOUTHERN 
CALIFORNIA FRIDAY NIGHT AND SATURDAY...BRINGING CHANCES FOR VALLEY 
RAIN AND MOUNTAIN SNOW. THE LOW WILL MOVE AWAY ON SUNDAY...WITH HIGH 
PRESSURE RETURNING EARLY NEXT WEEK.
&&

.SHORT TERM...SATELLITE SHOWS CLEAR SKIES AREAWIDE. SURFACE OBS SHOW 
ABOVE NORMAL TEMPERATURES AND GENERALLY LIGHT WINDS...EXCEPT FOR 
LOCALLY GUSTY NORTH WINDS IN THE BULLHEAD CITY AREA. THE PRESSURE 
GRADIENT BETWEEN KELY AND KEED HAD COLLAPSED FROM 16.4 MB AT 8 PM 
LAST NIGHT TO 6.2 MB AT 2 PM THIS AFTERNOON...EXPLAINING THE REDUCED 
WIND SPEEDS AND AREAL COVERAGE DOWN THE RIVER VALLEY. MODELS REMAIN 
IN PRETTY GOOD AGREEMENT WITH THE INCOMING LOW...SEEN NEAR 42N 130W 
THIS AFTERNOON. AS THE TROUGH REACHES THE WEST COAST OVERNIGHT...THE 
FLOW SPLITS AND THE SOUTHERN END OF THE TROUGH FORMS A CLOSED LOW 
WHICH DIGS DOWN THE CALIFORNIA COAST TO SAN FRANCISCO TOMORROW 
AFTERNOON AND THEN TO THE MOJAVE DESERT SATURDAY AFTERNOON. THIS 
WILL BRING MOISTURE AND EASTERLY UPSLOPE FLOW TO THE EAST SIDE OF 
THE SIERRA FRIDAY NIGHT...AND HAVE RAISED POPS THERE. AS THE LOW 
SHIFTS SOUTH...THE MOISTURE AND FORCING WILL COME WITH IT...BUT THE 
LACK OF A WELL DEFINED NORTH SOUTH MOUNTAIN BARRIER FARTHER SOUTH 
WILL MAKE PRECIP PLACEMENT MORE PROBLEMATIC. BY SATURDAY AFTERNOON 
IT BECOMES VERY DIFFICULT TO PINPOINT THE HIGHEST PRECIP 
CHANCES...BUT THE LOWEST CHANCES APPEAR TO BE IN THE NORTHEAST CWFA 
WHICH WILL BE FARTHEST FROM THE LOW CENTER...SO TWEAKED POPS TO 
REFLECT THIS. SATURDAY NIGHT AND SUNDAY...THE LOW WILL SAG SOUTH TO 
SAN DIEGO AND THEN OFFSHORE OF THE BAJA IN RESPONSE TO RIDGING 
BUILDING INTO THE PACIFIC NORTHWEST...THUS ALLOWING DRY AIR TO 
SPREAD INTO OUR CWFA FROM THE NORTH. POPS REFLECT THIS...WITH ONLY 
SLIGHT CHANCES REMAINING IN CENTRAL AND SOUTHERN MOHAVE COUNTY BY 
THE END OF THE SHORT TERM SUNDAY AFTERNOON. AS THE LOW PASSES 
BY...TEMPERATURES WILL FALL IN RESPONSE TO FALLING HEIGHTS AND 
INCREASING CLOUDS AND PRECIP CHANCES. POINT TEMPERATURES WILL BE 
HIGHLY DEPENDENT ON CLOUD AMOUNTS AND PRESENCE/TIMING OF SHOWERS 
AND/OR VIRGA...THUS CONFIDENCE IN POINT TEMPS IS LOW. NORTH WINDS 
WILL LIKELY OVERSPREAD THE CWFA AS THE LOW MOVES AWAY TO THE 
SOUTH...WITH SPEEDS DEPENDENT ON THE EXACT TRACK OF THE LOW. WIND 
ADVISORIES MAY BE NEEDED AT SOME TIME FOR AREAS PRONE TO NORTH WINDS.

.LONG TERM...BY MONDAY THE AFOREMENTIONED SYSTEM IS FORECAST TO BE 
OVER SONORA ALLOWING DRIER AIR TO SPREAD ACROSS THE ENTIRE CWFA 
BRINGING ABUNDANT SUNSHINE. THE ONLY CONCERN WILL BE WINDS AS A 
PROGGED 16 MB ELY-NEEDLES SFC PRESSURE GRADIENT WILL BE SITTING OVER 
THE AREA EARLY MONDAY MORNING BEFORE GRADUALLY RELAXING BY THE LATE 
AFTERNOON. EXPECT GUSTY NORTHERLY WINDS IN AREAS THAT FAVOR THIS 
DIRECTION...ESPECIALLY DOWN THE COLORADO RIVER VALLEY...WHERE GUSTS 
TO AROUND 30 MPH CERTAINLY LOOK POSSIBLE. OTHERWISE WITH THE GFS 
BUFR SOUNDINGS SHOWING A SHALLOW INVERSION IN THE VALLEYS IN THE 
AFTERNOON AND NORTHEAST FLOW PRESENT I UNDERCUT MOS NUMBERS AS 
COLDER AIR SHOULD HAVE TROUBLE GETTING MIXED OUT. AN UPPER RIDGE 
MOVES IN OVERHEAD MONDAY NIGHT INTO TUESDAY AND THIS SHOULD RESULT 
IN A WARMER AFTERNOON ON TUESDAY THOUGH MIXING STILL LOOKS MINIMAL 
AND AGAIN UNDERCUT MOST OF THE FORECAST GUIDANCE VALUES FOR MAX 
TEMPS. 

BY WEDNESDAY THE NEXT SYSTEM LOOKS TO APPROACH FROM THE NORTH AND 
FOR NOW HAVE FOLLOWED THE 12Z ECMWF/GEM WHICH WERE MORE CONSISTENT 
AND SHOWED A SYSTEM PASSING BY TO THE NORTHEAST OF THE AREA. DUE TO 
THE TRAJECTORY OF THIS SYSTEM JUST EXPECT AN INCREASE IN HIGH LEVEL 
CLOUDS AND AN ENHANCEMENT OF WINDS ESPECIALLY OUT OF THE NORTH 
WEDNESDAY NIGHT ONCE THE SYSTEM PASSES BY. DRY NORTHWEST FLOW IS 
EXPECTED FOR THURSDAY AND FRIDAY HOWEVER HIGH TEMPS SHOULD BE RIGHT 
AT OR JUST BELOW NORMAL. 
&&

.AVIATION...FOR MCCARRAN...LIGHT AND VARIABLE WINDS THROUGH FRIDAY 
AFTERNOON. A CLEAR SKY TONIGHT WITH FEW-SCT CLOUDS AOA 25K FEET 
FRIDAY AFTERNOON. A STORM SYSTEM WILL APPROACH THE AREA ON SATURDAY 
BRINGING THE POSSIBILITY OF CLOUD LAYERS AS LOW AS 8K FEET AND EVEN 
THE POSSIBILITY OF A FEW SHOWERS TO SOUTHERN NEVADA.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...MAINLY LIGHT WINDS TONIGHT FOLLOWING DIURNAL 
DIRECTIONAL TRENDS. FOR FRIDAY LIGHT WINDS ARE EXPECTED OVER THE 
MOJAVE DESERT WITH WINDS TURNING TO THE SOUTH AND GUSTING TO 15-20 
KTS AT TIMES OVER THE SOUTHERN GREAT BASIN BY THE AFTERNOON. FEW-SCT 
CLOUDS AOA 25K FEET TONIGHT IN THE NORTH WITH THESE CLOUDS SPREADING 
SOUTH INTO THE MOJAVE DESERT FRIDAY AFTERNOON. OVER THE SOUTHERN 
GREAT BASIN EXPECT SCT-BKN CLOUDS AOA 20K FEET WITH FEW-SCT CLOUDS 
AS LOW AS 15K FEET BY FRIDAY EVENING OVER THE WESTERN PART OF INYO 
COUNTY. A SYSTEM WILL APPROACH THE AREA FRIDAY NIGHT INTO SATURDAY 
BRINGING THE CHANCE OF SCATTERED SHOWERS TO THE AREA ESPECIALLY TO 
THE HIGHER ELEVATIONS.
&&

.CLIMATE...SO FAR THROUGH 2 PM TODAY THE AVERAGE TEMPERATURE FOR THE 
NOVEMBER AT MCCARRAN INTERNATIONAL AIRPORT HAS BEEN 59.8 DEGREES. 
GIVEN THE CURRENT FORECASTED NUMBERS THERE IS SOME POTENTIAL FOR LAS 
VEGAS TO SEE THIS NOVEMBER RANK AMONG THE 10 WARMEST ON RECORD. THE 
WARMEST NOVEMBERS ON RECORD AT LAS VEGAS ARE...

1. 60.9 DEGREES IN 2007
2. 60.8 DEGREES IN 2008
3. 59.8 DEGREES IN 1995
4. 59.3 DEGREES IN 2005
5. 58.9 DEGREES IN 1949
6. 58.8 DEGREES IN 1999
7. 58.6 DEGREES IN 2001
8. 58.4 DEGREES IN 2006
9. 58.0 DEGREES IN 1976 AND 1981
&&

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

$$

MORGAN/STACHELSKI

HTTP://WEATHER.GOV/LASVEGAS