Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 221711
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
910 AM PST MON DEC 22 2014

.SYNOPSIS...A STRONG JET STREAM WILL MOVE ACROSS UTAH TODAY
RESULTING IN A PUSH OF GUSTY NORTH WINDS DEVELOPING ACROSS THE AREA
FROM LATE THIS MORNING INTO EARLY THIS EVENING. TEMPERATURES WILL BE
NEAR RECORD LEVELS TODAY THEN LOWER BACK TO ABOUT 5-8 DEGREES ABOVE
NORMAL FOR TUESDAY. DRY AND MILD WEATHER IS EXPECTED FOR CHRISTMAS
EVE. A STORM SYSTEM WILL PASS ACROSS THE AREA ON CHRISTMAS DAY
BRINGING THE POTENTIAL FOR SOME SHOWERS TO THE SOUTHERN GREAT BASIN
AND WIDESPREAD GUSTY WINDS. MUCH COLDER AIR IS EXPECTED FOR THE END
OF THE WEEK WITH MANY AREAS SEEING LOWS NEAR OR BELOW FREEZING ONCE
AGAIN.
&&

.UPDATE...
THE FORECAST IS IN GOOD SHAPE THIS MORNING...ONLY MADE MINOR
ADJUSTMENTS TO ALIGN THE NEAR-TERM FORECAST TO CURRENT OBSERVATIONS.
TEMPERATURES HAVE BEEN RUNNING SEVERAL DEGREES WARMER THAN THIS TIME
YESTERDAY...MAINLY BECAUSE OF THE STEADY WIND ACROSS THE REGION.
STILL EXPECTING BREEZY NORTH WINDS TODAY. SLIGHTLY STRONGER WINDS
ARE ANTICIPATED ACROSS ESMERALDA AND NYE COUNTIES...THE WIND
ADVISORY LOOKS GOOD FOR THAT AREA. AFTERNOON HIGHS WILL DEPEND ON
HOW MUCH MIXING OCCURS. LAS VEGAS COULD REACH OR BREAK 70 DEGREES IF
WINDS MIX DOWN THE ANOMALOUSLY WARM AIR ALOFT. LAS VEGAS AND OTHER
SITES AROUND THE FORECAST AREA COULD SET NEW RECORD HIGH
TEMPERATURES THIS AFTERNOON.
&&

.PREVIOUS DISCUSSION...
322 AM PST MON DEC 22 2014

.SHORT TERM...TODAY THROUGH CHRISTMAS EVE.

SOME GOOD NEWS TODAY FOR FANS OF THE SUN AS THE PERSISTENT SHIELD OF
CIRRUS HAS FINLAY HEADED OFF TO THE EAST. MUCH OF THE AREA HAS
TRENDED CLEAR OR IS CLEAR AND WILL STAY THAT WAY TODAY. THERE COULD
BE A LITTLE FOG THAT DEVELOPS BRIEFLY THIS MORNING ACROSS FAR NW SAN
BERNARDINO AND SOUTHWEST INYO COUNTIES DUE TO LINGERING LOW-LEVEL
MOISTURE.

HIGH PRESSURE ALOFT HAS SET UP OFF THE COAST OF CALIFORNIA AND WILL
HOLD THERE THROUGH EARLY CHRISTMAS EVE. MEANWHILE THE DRIVER OF
TODAY`S WEATHER WILL BE A STRONG 140-160 KT+ JET STREAM AT 250 MB
PROGGED TO PLOW ACROSS UTAH. THIS JET WILL BRING A PUSH OF STRONG
NORTH WINDS TO THE AREA STARTING LATE THIS MORNING OR EARLY
AFTERNOON THAT WILL LAST INTO EARLY THIS EVENING. NORTH-SOUTH
SURFACE PRESSURE GRADIENTS ALSO TIGHTEN IN RESPONSE TO A SURFACE
HIGH BUILDING INTO IDAHO AND NORTHERN NEVADA. THIS WILL ALSO HELP TO
INCREASE WINDS. 700 MB WINDS OFF THE GFS AND ECMWF ARE PROGGED UP TO
50 KTS THIS AFTERNOON, HOWEVER, 850 MB WINDS ARE SHOWN TO BE MUCH
LIGHTER. THUS MOST AREAS WILL SEE GUSTS BETWEEN 20 AND 30 MPH WITH
THE HIGHEST SPEEDS IN AREAS THAT FAVOR NORTHWEST TO NORTH WINDS SUCH
AS THE COLORADO RIVER VALLEY, NORTHWEST PART OF THE LAS VEGAS VALLEY
AND MOST NOTABLY ESMERALDA AND CENTRAL NYE COUNTIES. A WIND
ADVISORY WAS ISSUED FOR THE LATTER AS GUSTS HERE MAY REACH 45 MPH.
LOCAL LAKE WIND ADVISORY CRITERIA MAY BE REACHED NEAR BULLHEAD CITY
AND LAUGHLIN BRIEFLY THIS AFTERNOON BUT THIS IS SUCH A SMALL AREA
THAT NO HEADLINE WILL BE ISSUED FOR THIS.

THE OTHER BIG IMPACT OF THIS WIND TODAY IS THAT IT WILL BREAK UP THE
INVERSION BY THIS AFTERNOON AND MIX DOWN WARMER AIR ALOFT TOWARD THE
SURFACE. BOTH THE GFS AND ECMWF SHOW 850 MB TEMPS NEAR +12C ACROSS
THE AREA, WHICH IS QUITE HIGH FOR LATE DECEMBER. ONCE THE INVERSION
BREAKS AND WE MIX, TEMPS WILL SOAR NEAR OR ABOVE RECORD LEVELS FOR
TODAY, ESPECIALLY IN LAS VEGAS WHICH COULD HIT 70 OR BETTER THIS
AFTERNOON. HOWEVER, GIVEN THE SHORT AMOUNT OF DAYLIGHT I HAVE KEPT
THE FORECASTED HIGH FOR MCCARRAN AT 69.

COOLER AIR IS EXPECTED TONIGHT ACROSS THE AREA AND FOR TOMORROW WITH
HIGHS FALLING SEVERAL DEGREES BUT STILL WE SHOULD SEE READINGS 5-8
DEGREES ABOVE NORMAL. HOWEVER, THE INVERSION DOES NOT HAVE ANYTHING
TO BREAK IT ON TUESDAY, AND THUS LOWER VALLEYS WILL NOT HAVE THE
POTENTIAL TO WARM-UP TO WHAT WE SHOULD SEE TODAY. WITH LOW-LEVEL
MOISTURE LINGERING, WE WILL HAVE TO WATCH OUT AGAIN TONIGHT AND
POSSIBLY TUESDAY NIGHT IN NW SAN BERNARDINO AND FAR SW INYO COUNTIES
FOR PATCHY FOG TO RETURN. BUFKIT SOUNDINGS FOR CHINA LAKE NAS STILL
SHOW THE POTENTIAL AND WITH LIGHT WINDS AND A CLEAR SKY, THE
INGREDIENTS ARE CERTAINLY THERE.

THE HIGH ALOFT OFFSHORE WILL WEAKEN ON CHRISTMAS EVE IN RESPONSE TO
A NORTHERN STREAM MID/UPPER LEVEL TROUGH THAT DIGS SOUTH OFF THE
COAST OF THE PAC NW. CHRISTMAS EVE ITSELF WILL STILL BE MILD WITH
HIGHS STILL 5-8 DEGREES ABOVE NORMAL. WINDS SHOULD START TO PICK UP
BY THE AFTERNOON AND ESPECIALLY THE EVENING ACROSS THE WESTERN CWFA,
ESPECIALLY OVER THE SOUTHERN SIERRA AND WHITE MTS AS A 100 KT+ JET
AT 250 MB MOVES DIRECTLY OVERHEAD. 500 MB HEIGHTS SHOW A HYDRAULIC
JUMP SIGNATURE TO THE LEE AND THE SET-UP LOOKS GOOD FOR THE
POTENTIAL OF A CHRISTMAS EVE DOWNSLOPE WIND EVENT IN THE OWENS
VALLEY AND POSSIBLY THE FISH LAKE VALLEY.

WHILE THE MODELS KEEP THE AREA DRY CHRISTMAS EVE DAY, SANTA MAY HAVE
SOME ISSUES TO CONTEND WITH CHRISTMAS EVE NIGHT AS MOISTURE STARTS
TO SPILL ON EAST. A BLEND OF THE 00Z OPERATIONAL ECMWF, GFS AND WRF
ALL SPREAD LIGHT PRECIPITATION INTO THE NORTHERN CWFA CHRISTMAS EVE
NIGHT AND POPS WERE INCREASED. 700 MB TEMPS ARE PROGGED TO BE -4 TO
-8C WHICH WOULD PUT SNOW LEVELS AROUND 5000-5500 FEET. LIGHT SNOW
MAY MAKE TRAVEL IN INYO, ESMERALDA, CENTRAL NYE AND NORTHERN LINCOLN
COUNTIES SLICK ON CHRISTMAS MORNING AND REDUCE VISIBILITY FOR THE
REINDEERS. ELSEWHERE IT LOOKS DRY BUT ON THE CLOUDY SIDE FOR THOSE
OUT AND ABOUT ON CHRISTMAS EVE NIGHT.

.LONG TERM...CHRISTMAS DAY THROUGH SUNDAY.

A QUICK HITTING TROUGH STILL LOOKS TO BE ON TRACK CHRISTMAS DAY. THE
MAIN IMPACT OF THIS SYSTEM WILL BE GUSTY WINDS...COOLER TEMPERATURES
AND SOME SNOW SHOWERS PRIMARILY ACROSS CENTRAL AND EASTERN NEVADA.
THE LATEST MEDIUM RANGE MODELS CONTINUE TO SHOW SOME DISAGREEMENT IN
THE DEPTH OF THE TROUGH...THE ECMWF BEING THE DEEPEST...BUT ALL SHOW
A FAST MOVING OPEN WAVE WITH THE AXIS CROSSING THE GREAT BASIN
BETWEEN 06Z AND 18Z THURSDAY. SINCE THE ECMWF IS A BIT OF AN
OUTLIER...THE FORECAST GRIDS ARE GEARED MORE TOWARD THE GFS/SREF
SOLUTIONS WHICH KEEP THE COLD CORE OF THE TROUGH MORE OVER THE
NORTHEAST CORNER OF NEVADA AND NEARBY IDAHO AND UTAH. THE TROUGH
AXIS IS FORECAST TO MOVE ACROSS THE ROCKIES LATE THURSDAY INTO
FRIDAY LEAVING OUR FORECAST AREA UNDER A STIFF NORTHWEST TO
NORTHERLY FLOW ON THE BACK SIDE OF THE TROUGH. THIS WILL FAVOR GUSTY
NORTH WINDS...ESPECIALLY DOWN THE COLORADO RIVER VALLEY...THURSDAY
NIGHT INTO FRIDAY. TEMPERATURES WILL COOL SEVERAL DEGREES AND
OVERNIGHT LOWS WILL DIP NEAR THE FREEZING MARK IN SOME AREAS IN
SOUTHERN NEVADA AND SURROUNDING AREAS OF THE MOJAVE DESERT REGION.

THE PATTERN REMAINS PROGRESSIVE THROUGH THE WEEKEND WHICH WILL LEAD
TO A RIDGE BRIEFLY MIGRATING OVERHEAD SATURDAY AHEAD OF ANOTHER
TROUGH DIVING ACROSS THE PACIFIC NORTHWEST AND DROPPING INTO THE
GREAT BASIN SUNDAY...LIKELY INCREASING WINDS AGAIN LATE IN THE
WEEKEND AND EARLY NEXT WEEK.
&&

.AVIATION...FOR MCCARRAN...WINDS SHOULD STAY 6-12 KTS THIS MORNING
AND INCREASE SLIGHTLY THIS AFTERNOON AS THEY SHIFT MORE WEST AND
EVENTUALLY NORTHWEST ESPECIALLY AFTER 20Z TODAY. WINDS SHOULD SHIFT
FROM CONFIGURATION 1 TO FAVORING CONFIGURATION 3 AROUND 20Z TODAY
AND HOLD FROM THE NORTHWEST INTO TONIGHT. GUSTS OF 20-25 KTS ARE
POSSIBLE AT TIMES. WINDS WILL REMAIN GUSTY OFF AND ON THROUGH
TONIGHT. SCT CLOUDS AOA 25K FEET THIS MORNING TRANSITIONING TO FEW
BY TONIGHT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS SHOULD STAY 6-12 KTS THIS MORNING AND INCREASE
SLIGHTLY THIS AFTERNOON AS THEY SHIFT MORE WEST AND EVENTUALLY
NORTHWEST ESPECIALLY AFTER 16Z-21Z TODAY WITH LOCATIONS FURTHER
NORTH SUCH AS KBIH INCREASING FIRST. GUSTS OF 20-30 KTS ARE POSSIBLE
AT TIMES. MECHANICAL TURBULENCE ALOFT IS POSSIBLE. WINDS WILL REMAIN
GUSTY OFF AND ON THROUGH TONIGHT. SCT CLOUDS AOA 25K FEET THIS
MORNING TRANSITIONING TO FEW BY TONIGHT.
&&

.CLIMATE...HIGH TEMPERATURES WILL BE CLOSE TO RECORD LEVELS TODAY AT
SOME LOCATIONS ESPECIALLY LAS VEGAS. RECORD HIGHS ARE LISTED BELOW.

LAS VEGAS          68/1950
DESERT ROCK        69/1985
MT CHARLESTON      56/2005
BISHOP             71/2000
BARSTOW-DAGGETT    78/1955
DEATH VALLEY       82/1914
NEEDLES            74/1955
KINGMAN            72/1906
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING
PROCEDURES.
&&

$$

UPDATE...PADDOCK
SHORT TERM/AVIATION...STACHELSKI
LONG TERM...ADAIR

FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:

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