Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 250410 AAA
AFDREV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
810 PM PST WED DEC 24 2014

.UPDATE...

THE COLD FRONT RAPIDLY PUSHED THROUGH THE REGION THIS EVENING WITH
SNOW QUICKLY TAPERING OFF BEHIND IT. THE MAIN FRONT IS NOW SOUTH
OF HIGHWAY 50 WITH STEADY SNOW ENDING FOR MOST LOCATIONS. HOWEVER,
A WEAK DEFORMATION BAND IS DEVELOPING SHOWERS NORTH OF INTERSTATE
80 NEAR PYRAMID LAKE, WHICH WILL SHIFT SOUTH. PERIODS OF SNOW
SHOWERS ARE POSSIBLE WITH THIS FEATURE, BUT WILL BE VERY
LOCALIZED. CURRENT RADAR TRENDS LOOK LIKE IT WILL PASS OVER
INTERSTATE 80, BUT EAST OF RENO. HAVE EXPIRED THE SNOW ADVISORIES
FOR NORTHEAST CALIFORNIA, THE SURPRISE VALLEY, AND NORTHERN WASHOE
COUNTY ON TIME AT 7 PM AND CANCELLED THE REMAINING SNOW ADVISORIES
FOR THE SIERRA AND WESTERN NEVADA EARLY. ANY ADDITIONAL
ACCUMULATION FROM THESE LINGERING SHOWERS WILL BE NEGLIGIBLE WITH
MINIMAL ADDITIONAL IMPACTS. KEEP IN MIND THAT TEMPERATURES WILL BE
BELOW FREEZING EVERYWHERE TONIGHT AND ANY LOCATIONS THAT RECEIVED
RAIN OR SNOW TODAY WILL LIKELY BE ICY THROUGH CHRISTMAS MORNING.
TAKING A LOOK AT WEBCAMS AND ROAD REPORTS, CHAINS ARE REQUIRED
THROUGH MUCH OF THE SIERRA INTO PORTIONS OF NORTHEAST CALIFORNIA
WITH SNOW COVERED ROADS. SLOW DOWN AND ALLOW EXTRA TIME TO REACH
YOUR DESTINATION IF YOU HAVE PLANS TO TRAVEL THIS EVENING OR EARLY
CHRISTMAS MORNING.


&&

.PREVIOUS DISCUSSION... /ISSUED 315 PM PST WED DEC 24 2014/

SYNOPSIS...

A STRONG COLD FRONT WILL PUSH THROUGH THE REGION TONIGHT INTO
CHRISTMAS DAY. EXPECT GUSTY WINDS AND SNOW DOWN TO THE VALLEY FLOORS
OF WESTERN NEVADA AND NORTHEASTERN CALIFORNIA. TRAVEL WILL BECOME
DIFFICULT AS THE FRONT MOVES THROUGH DUE TO BRIEF HEAVY SNOW.
TEMPERATURES BECOME MUCH COLDER BY THE WEEKEND WITH LOW CHANCES OF
SNOW SHOWERS EARLY NEXT WEEK.

SHORT TERM...

LOW PRESSURE SYSTEM CONTINUES TO PUSH INTO NORTHERN CA/NV THIS
AFTERNOON, SPREADING PRECIP ACROSS THE SIERRA AND MUCH OF WESTERN
NEVADA. GUSTY WINDS WILL CONTINUE AS WELL, ALTHOUGH AS THE PRECIP
MOVES IN, THE WINDS WILL BACK OFF AS WELL. BLOWING DUST IS STILL A
CONCERN THROUGH THE REST OF THE AFTERNOON FOR THE WESTERN NEVADA
BASIN AND RANGE.

SNOW LEVELS ARE A BIT HIGHER THAN PREVIOUSLY EXPECTED, RIGHT AROUND
6500 FEET FOR THE RENO-CARSON-TAHOE AREA. THE COLD FRONT--CURRENTLY
NORTH OF SUSANVILLE--IS STILL EXPECTED TO MOVE THROUGH THE REGION
THIS EVENING.  COLD FRONT WILL MOVE INTO THE RENO-SPARKS-CARSON
AFTER 4 PM AND SNOW LEVELS ARE STILL EXPECTED TO FALL TO ALL VALLEY
FLOORS BEHIND THE FRONT. IN FACT, THE FRONT ALREADY PASSED THROUGH
ALTURAS AND SURPRISE VALLEY IN FAR NORTHEASTERN CALIFORNIA AND
BROUGHT SNOW LEVELS DOWN QUICKLY. STRONG INSTABILITY IS CAUSING
LIGHTNING IN THE SIERRA AS WELL. THIS THREAT OF THUNDER SNOW WILL
CONTINUE IN THE EVENING HOURS AS WELL, WITH THIS DEEP UNSTABLE
ATMOSPHERE.

FOR THE VALLEY FLOORS, RAIN WILL MIX WITH SNOW, THEN CHANGE OVER TO
ALL SNOW BEHIND THE COLD FRONT. THE STRONG FRONT WILL ALLOW FOR
EXCELLENT FORCING AND INSTABILITY WITH A PERIOD OF MODERATE TO HEAVY
SNOW POSSIBLE. AS THE SUN GOES DOWN THIS EVENING, THE ROADS WILL
COOL OFF EVEN MORE, CREATING SLICK AND ICY ROAD CONDITIONS FOR
WESTERN NEVADA AND THE SIERRA. DUE TO THE WARM TEMPERATURES THIS
AFTERNOON, MELTED SNOW AND RAIN THAT FELL EARLIER WILL BE PRONE TO
RE-FREEZING. THIS COULD CREATE A DANGEROUS SITUATION WITH SNOW ON
TOP OF A LAYER OF ICE. ALSO, DUE TO THE INTENSITY OF THE PRECIP, WE
COULD SEE QUICKLY DETERIORATING VISIBILITIES AS SNOW RATES APPROACH
2 INCHES PER HOUR. ANYONE TRAVELING THIS EVENING OR TONIGHT SHOULD
BE PREPARED FOR WINTER DRIVING CONDITIONS AND POSSIBLE DELAYS
THROUGH CHRISTMAS MORNING.

STILL EXPECTING SNOW AMOUNTS IN IN THE TAHOE BASIN ABOVE 7000 FEET
UP TO 12 INCHES...UP TO 6 INCHES IN MONO COUNTY AND LASSEN-PLUMAS
WEST OF HIGHWAY 395. HIGH SNOW RATIOS UP TO 15:1 ARE EXPECTED IN THE
HIGH SIERRA DUE TO THE VERY COLD AIR BEHIND THE FRONT. IN THE LOWER
VALLEYS OF NORTHEASTERN CALIFORNIA AND WESTERN NEVADA LIGHT SNOW
ACCUMULATIONS AROUND AN INCH IS EXPECTED ON THE VALLEY FLOORS THIS
EVENING WITH UP TO 3 INCHES ABOVE 5000 FEET. WINTER WEATHER
ADVISORIES FOR SNOW AND BLOWING SNOW REMAIN IN PLACE THROUGH 10 PM
TONIGHT.

VERY COLD TEMPERATURES FILTER IN TONIGHT AND ON CHRISTMAS DAY BEHIND
THE COLD FRONT. EXPECT BLUSTERY NORTH WINDS WITH TEMPERATURES IN THE
30S FOR THE BASIN VALLEYS AND 20S IN THE EASTERN SIERRA. OVERNIGHT
LOWS WILL DIP INTO THE SINGLE DIGITS FOR MANY LOCATIONS OVER THE
NEXT FEW NIGHTS AS WELL. HOON

LONG TERM...SUNDAY THROUGH NEW YEARS EVE...

A HIGH AMPLITUDE RIDGE DEVELOPING OVER THE PACIFIC ALONG 140W WILL
PERSIST THROUGH THE LONG TERM. THIS LARGE SCALE SET UP SHOULD LEAD
TO A COLD NORTH FLOW WITH THE POTENTIAL FOR A FEW PERIODS OF LIGHT
SNOW SHOWERS INTO THE FINAL WEEK OF 2014. MODEL DIFFERENCES REMAIN
ON EXACT TIMING AND LOCATION OF ENERGY AND REINFORCING PIECES OF
COLD AIR DROPPING SOUTH INTO THE REGION, BUT MEDIUM CONFIDENCE FOR A
COLD NORTHERLY FLOW ACROSS THE AREA. THE STRONGEST SYSTEM MAY DROP
INTO THE REGION TUESDAY INTO NEW YEAR`S EVE DAY. THE MAIN CONCERN
WILL BE BREEZY WINDS, AND HIGHS FALLING INTO THE UPPER 20S TO MID
30S FOR THE NEVADA VALLEYS, WITH LIGHT SNOW ACCUMULATIONS POSSIBLE.

FOR THE SIERRA, MOST OF THE ENERGY WILL REMAIN TOO FAR EAST, BUT
COLD AND DRY CONDITIONS WILL PERSIST THROUGH THE PERIOD. THE BIGGER
IMPACT FOR THE SIERRA WILL BE THE POTENTIAL FOR A MODERATE TO STRONG
NORTHEAST TO EAST WIND EVENT. GFS AND THE ECMWF SHOW A STRONG
NORTHEAST TO EAST OFFSHORE FLOW STARTING TUESDAY AND PERSISTING INTO
NEW YEARS EVE DAY. THE COLD AIR BEHIND THE SYSTEM AND A 1040+ MB
SURFACE HIGH MAY LEAD TO STRONG PRESSURE AND THERMAL GRADIENTS ALONG
THE SIERRA CREST. THE JET MAY ALSO BE ALIGNED WITH THE SURFACE
GRADIENTS TO PROVIDE UPPER SUPPORT FOR 70-100 MPH RIDGE WINDS, WITH
POTENTIAL FOR 30-40 MPH WINDS ON LAKE TAHOE. WEISHAHN

AVIATION...

RAIN AND SNOW SHOWERS ALONG WITH LOW CEILINGS AND LOW VISIBILITY
WILL CONTINUE THROUGH 03Z WITH IMPROVING CONDITIONS AFTER THAT
TIME. SKIES WILL BEGIN TO CLEAR RAPIDLY AFTER 6Z AS WELL.
NORTHERLY WINDS WILL REMAIN BREEZY THROUGH 12Z THURSDAY WITH
FREEZING LEVELS AROUND 4000 FT MSL OR LESS.

FARTHER SOUTH FOR KMMH, 30-50KT SURFACE GUSTS MAY PERSIST THROUGH
06Z 12/25, WITH SNOW AND IFR CONDITIONS POSSIBLE 06Z-12Z 12/25.

CLEARING SKIES WITH LITTLE TO NO CHANCES FOR PRECIPITATION EXPECTED
FOR CHRISTMAS DAY. WINDS WILL ALSO BEGIN TO SHIFT TO THE NORTHEAST
AND EAST TOMORROW FOR KTRK, KTVL, KRNO, KCXP, WHILE KMMH MAY REMAIN
NORTHERLY THROUGH THE DAY. 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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