Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 222331 CCA
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
331 PM PST MON DEC 22 2014

.SYNOPSIS...

DRY CONDITIONS AND MILD TEMPERATURES ARE ANTICIPATED THROUGH
WEDNESDAY AS HIGH PRESSURE BUILDS. A STRONG COLD FRONT WILL PUSH
THROUGH THE REGION LATE WEDNESDAY INTO CHRISTMAS DAY WITH GUSTY
WINDS, RAIN, AND SNOW.


&&

.SHORT TERM...

BREEZY WINDS TODAY HAVE ALLOWED US TO MIX WELL WITH TEMPERATURES
REACHING INTO THE LOW 60S ACROSS MUCH OF WESTERN NEVADA. PATCHY
FREEZING FOG IS EXPECTED AGAIN TONIGHT IN THE SIERRA VALLEYS,
INCLUDING AROUND TRUCKEE. THE RIDGE OF HIGH PRESSURE CONTINUES TO
BUILD OVER THE WEST COAST THROUGH TUESDAY WITH THE PRESSURE GRADIENT
RELAXING A BIT. THIS WILL ALLOW FOR CALMER WINDS, LESS MIXING AND
COOLER TEMPERATURES THAN WE SAW TODAY...STILL ABOUT 10 DEGREES ABOVE
NORMAL FOR LATE DECEMBER.

AS WE GO INTO CHRISTMAS EVE (WEDNESDAY), A STRONG AND FAST MOVING
SHORTWAVE WILL DROP INTO NORTHERN CA/NV. THE COLD FRONT DOESN`T MOVE
THROUGH UNTIL WEDNESDAY NIGHT INTO EARLY CHRISTMAS MORNING, BUT THE
MAIN IMPACT AHEAD OF THE FRONT ON WEDNESDAY WILL BE STRONG WINDS.
GRADIENTS AND WINDS ALOFT WILL INCREASE SHARPLY WEDNESDAY AHEAD OF
THE FRONT. VALLEY GUSTS UP TO 55 MPH ARE LIKELY ON WEDNESDAY
AFTERNOON, ESPECIALLY ALONG THE HIGHWAY 395 CORRIDOR WHERE GUSTS UP
TO 65 MPH WILL BE POSSIBLE. DEEP MIXING WILL ALSO PUSH TEMPERATURES
UP INTO THE LOW 60S IN WESTERN NEVADA. AREAS OF BLOWING DUST ARE ALSO
LIKELY EAST OF HIGHWAY 395, ESPECIALLY IN PERSHING, CHURCHILL, AND
MINERAL COUNTIES.

ON WEDNESDAY EVENING, A VERY STRONG AND DYNAMIC COLD FRONT WILL
SWEEP ACROSS THE REGION. FORECAST CONFIDENCE IS HIGH THAT THIS
SHORTWAVE WILL BRING A STRONG COLD FRONT THROUGH THE REGION (MODELS
HAVE BEEN SHOWING THIS POTENTIAL SINCE LAST WEEK). AS FOR SPECIFIC
SNOW AMOUNTS, OUR FORECAST CONFIDENCE IS INCREASING BUT STILL MEDIUM
AT THIS TIME. THIS SHORTWAVE HAS TRENDED FURTHER OFFSHORE, WHICH
WILL ALLOW IT TO PICK UP A DECENT AMOUNT OF MOISTURE OVER THE
PACIFIC BEFORE IT MOVES ONSHORE WEDNESDAY NIGHT. THIS WILL PUSH A
QUICK BURST OF SNOW INTO THE SIERRA AND INTO WESTERN NEVADA AS WELL.
IN THE SIERRA, MODERATE SNOW TOTALS UP TO 6 INCHES ARE POSSIBLE
ABOVE 7000 FEET, WITH A FEW INCHES AROUND LAKE TAHOE LEVEL. SNOW
LEVELS WILL DROP VERY QUICKLY WEDNESDAY NIGHT BEHIND THE COLD FRONT,
DROPPING FROM AROUND 6000 FEET TO VIRTUALLY ALL VALLEY FLOORS BY
MIDNIGHT.

VERY UNSTABLE CONDITIONS AND LOW LEVEL FORCING ALONG THE COLD FRONT
WILL LIKELY BRING PRECIP DOWN TO VALLEY FLOORS IN WESTERN NEVADA AND
NORTHEASTERN CALIFORNIA AS WELL. SINCE THE FRONT IS VERY DYNAMIC AND
COMING THROUGH AT NIGHT, CHANCES ARE THAT PRECIP WILL COME AS SNOW
ON THE VALLEY FLOORS, ALTHOUGH PRECIPITATION MAY MIX WITH RAIN
FOR A SHORT TIME AND THEN QUICKLY BECOME ALL SNOW BEHIND THE FRONT.
FOR NOW, UP TO AN INCH OF SNOW IS FORECAST BY EARLY CHRISTMAS
MORNING ON THE VALLEY FLOORS AROUND RENO-SPARKS-CARSON CITY WITH UP
TO A FEW INCHES ABOVE 5000 FEET, INCLUDING VIRGINIA CITY. LIGHT SNOW
AMOUNTS ARE ALSO POSSIBLE OUT INTO THE VALLEYS OF NORTHEASTERN
CALIFORNIA AROUND SUSANVILLE AND SURPRISE VALLEY, AS WELL AS IN
WEST-CENTRAL NEVADA AROUND LOVELOCK, FALLON, AND FERNLEY.

WE`VE POSTED A PRELIMINARY SNOWFALL FORECAST ON OUR WEBPAGE
WWW.WEATHER.GOV/RENO AND ON OUR FACEBOOK PAGE. ANYONE TRAVELING
THROUGH THE SIERRA OR WESTERN NEVADA ON CHRISTMAS EVE NIGHT THROUGH
CHRISTMAS MORNING SHOULD BE PREPARED FOR POTENTIAL WINTER DRIVING
CONDITIONS. TEMPERATURES ON CHRISTMAS DAY WILL REMAIN IN THE 20S AND
30S, MORE THAN A 25 DEGREE DROP FROM CHRISTMAS EVE! DEPENDING ON HOW
MUCH AND HOW WIDESPREAD THE SNOWFALL, MAY NEED TO ADJUST
TEMPERATURES EVEN FURTHER DOWN THURSDAY NIGHT. HOON

.LONG TERM...FRIDAY THROUGH TUESDAY...

EXTENDED MODEL FORECAST CONTINUES TO SHOW A BLOCKING PATTERN
DEVELOPING ACROSS THE EASTERN PACIFIC AROUND 140W. WITH THE RIDGE
SETTING UP IN THAT LOCATION THIS WILL KEEP MOISTURE LADEN
ATMOSPHERIC RIVERS FROM STREAMING ACROSS THE PACIFIC INTO THE WEST
COAST, BUT IT WILL ALSO ALLOW COLD CANADIAN AIR TO STREAM SOUTHWARD
INTO THE SIERRA AND WESTERN NEVADA.

FOR THE WEEKEND INTO EARLY NEXT WEEK, THERE IS MEDIUM CONFIDENCE FOR
BELOW AVERAGE TEMPERATURES AS THE COLD NORTHERLY FLOW SETS UP ACROSS
THE GREAT BASIN. THE NEXT BEST SHOT FOR PRECIPITATION WILL BE ON
SATURDAY-SUNDAY AS A SYSTEM DROPS DOWN OUT OF THE GULF OF ALASKA.
MODELS ARE IN FAIR AGREEMENT WITH THIS SYSTEM IMPACTING THE REGION,
WITH MAIN DIFFERENCES BEING IN TRACK AND TIMING. THE ECMWF IS FASTER
AND FURTHER WEST THAN THE GFS AT THIS POINT, BUT WENT AHEAD AND LEFT
IN CHANCES FOR RAIN/SNOW SHOWERS NORTH OF HIGHWAY 50 FROM SATURDAY
THROUGH EARLY NEXT WEEK. WEISHAHN

&&

.AVIATION...

HIGH PRESSURE BUILDING ACROSS THE REGION TODAY WILL ALLOW SURFACE
WINDS TO REMAIN RELATIVELY LIGHT. ALTHOUGH MODERATE TO STRONG RIDGE
WINDS MAY STICK AROUND THROUGH 00Z TUESDAY, RESULTING IN BUMPY
APPROACHES AND DEPARTURES.

NEXT SYSTEM WILL ARRIVE ON WEDNESDAY WITH POTENTIAL FOR A STRONG
WIND EVENT. LATEST MODELS SHOW SURFACE GUSTS TO 50 KTS AS LOW
PRESSURE MOVES INTO NORTHERN CALIFORNIA, ALONG WITH GOOD MOUNTAIN
WAVE SIGNATURES. A COLD FRONT WILL MOVE INTO THE AREA ON CHRISTMAS
EVE, WHICH MAY BRING A ROUND OF LOW LEVEL WIND SHEAR AND A PERIOD OF
MODERATE TO HEAVY SNOW INTO EARLY CHRISTMAS MORNING. BRONG/WEISHAHN

&&


.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)










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