Winter Storm Heads into High Gear This Evening, dec. 10

Staff Writer

The storm is in full swing right now in Mammoth with a lot more to go. Here is what and when to expect the rest of it, and the forecast for the weekend ahead, as of this afternoon, Dec. 10

Forecast done at 4 pm:

A WINTER STORM WILL IMPACT THE REGION THROUGH TONIGHT WITH HIGH
WINDS, FOLLOWED BY HEAVY SNOW IN THE SIERRA AND RAIN FOR LOWER
ELEVATIONS. SNOW MAY ACCUMULATE IN LOWER VALLEYS BY EARLY FRIDAY
MORNING. ANOTHER COLDER STORM WILL LIKELY BRING MORE SNOW AND
WIND FOR SUNDAY AND SUNDAY NIGHT. BOTH OF THESE STORMS WILL
PRODUCE SIGNIFICANT TRAVEL IMPACTS ESPECIALLY NEAR THE SIERRA.

SHORT TERM...

OVERALL FORECAST REMAINS INTACT WITH SIGNIFICANT WIND AND
SNOW/RAIN IMPACTS ACROSS THE EASTERN SIERRA AND WESTERN NEVADA.
AS OF 3 AM, WINDS WERE BECOMING STRONG OUTSIDE THE NWS RENO
OFFICE, WHILE RAIN WAS SPREADING ACROSS NORTHEAST CA-NORTHWEST
NV.

SOME MINOR TIMING DIFFERENCES HAVE SHOWN UP ON THE LATEST
GUIDANCE DATA. THE ARRIVAL OF THE COLD AIR APPEARS TO BE DELAYED
BY A COUPLE OF HOURS, BUT ONCE THE FRONT AND MOISTURE SURGE
ARRIVES IT PROGRESSES SOUTHWARD AT A SLIGHTLY FASTER RATE. THIS
WOULD LIKELY LEAD TO A SHORTER PERIOD OF HIGH WINDS WITH THE PEAK
GUSTS OCCURRING THROUGH THIS MORNING, AND AN EARLIER END TO THE
STEADY PRECIP ESPECIALLY IN AREAS NORTH OF I-80. THIS TIMING
CHANGE MAY LIMIT THE OVERALL SNOW TOTALS A BIT IN THE 6500-7500
FOOT RANGE, BUT WE DIDN`T HAVE VERY HIGH TOTALS. WITH SNOWFALL
RATES LIKELY INCREASING TO 2-3 INCHES PER HOUR DURING THE PEAK
PERIOD OF INTENSITY TODAY, IT WOULD ONLY TAKE A FEW HOURS TO
APPROACH THE FORECAST VALUES. IN ADDITION, THE SECONDARY WAVE
WHICH WILL LIKELY BRING SOME BANDS OF SNOW WITH CONVECTIVE
ENHANCEMENT IS STILL ON TRACK TO REACH THE SIERRA TONIGHT. THESE
SNOW BANDS MAY START A LITTLE EARLIER IN THE EVENING AS MOST OF
THE LATEST GUIDANCE HAS ALSO SPED UP THE ARRIVAL OF THIS SYSTEM A
BIT. THE SAME MESSAGE OF AVOIDING TRAVEL AND BACKCOUNTRY ACTIVITY
ACROSS THE SIERRA TODAY AND TONIGHT STILL APPLIES, AS DANGEROUS
WHITEOUT CONDITIONS WILL OCCUR ACROSS LONG SECTIONS OF THE MAIN
HIGHWAYS, WITH LIFE THREATENING WIND CHILLS IN HIGHER ELEVATIONS.

FOR WESTERN NV, A PERIOD OF MODERATE TO HEAVY RAINFALL IS STILL ON
TRACK TO SPREAD QUICKLY ACROSS THE LOWER ELEVATIONS AROUND
DAYBREAK AND REACH WEST CENTRAL NV BY MID MORNING. THE QUICKER
SOUTHWARD PROGRESSION MAY LIMIT RAIN TOTALS SLIGHTLY, BUT MOST
AREAS SHOULD STILL RECEIVE BETWEEN 0.25 AND 0.50 INCH OF RAIN,
WITH TOTALS CLOSE TO 1 INCH ESPECIALLY WEST OF HIGHWAY 395. RAIN
MAY CHANGE TO SNOW IN SOME FOOTHILL LOCATIONS BY MID-LATE
AFTERNOON, BUT ACCUMULATION MAY BE DELAYED DUE TO THE PRECEDING
PERIOD OF RAIN. AIR TEMPERATURES ONLY DROP TO THE LOWER-MID
30S TONIGHT, WITH PAVEMENT MORE LIKELY TO BE WET OR SLUSHY FOR
MOST OF THE NIGHT IN THE LOWER VALLEYS. ROAD SURFACES NEAR AND
ABOVE 5000 FEET MAY BECOME SLICK WITH A LIGHT ACCUMULATION
(GENERALLY LESS THAN 2 INCHES) BY EARLY FRIDAY MORNING, BUT AT
THIS TIME THE IMPACTS AND SNOW AMOUNTS DO NOT APPEAR TO BE
WIDESPREAD ENOUGH FOR ISSUING A WINTER WEATHER ADVISORY IN THE
RENO-CARSON VICINITY.

FOR FRIDAY, THE SNOW WILL DIMINISH WITH ISOLATED-SCATTERED SNOW
SHOWERS MAINLY NEAR THE SIERRA AND NORTH OF SUSANVILLE-GERLACH.
TRAVEL IMPACTS ACROSS THE SIERRA WILL CONTINUE THROUGH THE FRIDAY
MORNING COMMUTE, WHILE COOLER CONDITIONS WILL PREVAIL ACROSS THE
REGION WITH HIGHS ONLY IN THE 30S TO LOWER 40S.

A SHORT BREAK IN PRECIPITATION IS EXPECTED ACROSS MOST OF THE
REGION FRIDAY NIGHT, BEFORE WE HEAD INTO MORE ACTIVE WEATHER AGAIN
FOR THE WEEKEND. WHILE THE MOST SIGNIFICANT WEATHER IMPACTS ARE
EXPECTED ON SUNDAY (SEE THE LONG TERM SEGMENT FOR MORE DETAILS), A
LEADING SHORTWAVE MOVING ACROSS NORTHERN CA SATURDAY WILL BRING
STRONG WARM ADVECTION ALOFT ALONG WITH ABUNDANT MOISTURE NORTH OF
SUSANVILLE AND GERLACH. WE ARE INCREASING THE PRECIP CHANCES
ACROSS THESE AREAS, AND IF THIS WAVE COMES IN ON THE STRONG SIDE
(AND TRACKS FAR ENOUGH SOUTH), SEVERAL INCHES OF SNOW COULD
ACCUMULATE ACROSS PORTIONS OF NORTHEAST CA-NORTHWEST NV.
OTHERWISE, CONTINUED COOL TEMPS WILL CONTINUE ON SATURDAY WITH
WIDESPREAD CLOUD COVER, AND WINDS INCREASING IN HIGHER ELEVATIONS
DURING THE AFTERNOON. GUSTY WINDS MAY BEGIN TO SPREAD INTO LOWER
ELEVATIONS BY SATURDAY NIGHT. MJD

.LONG TERM...SUNDAY THROUGH WEDNESDAY...

FORECASTER CONFIDENCE CONTINUES TO REMAIN MODERATE TO HIGH
CONCERNING ANOTHER WINTER STORM SYSTEM AFFECTING THE REGION SUNDAY
AND SUNDAY NIGHT. THE TIMING OF THE COLD FRONT REMAINS TO BE THE
UNCERTAINTY FOR SUNDAY, AS MODELS SEEM TO BE SPEEDING UP THE FRONTAL
PASSAGE SUNDAY AFTERNOON, A FULL 6 HOURS FASTER THAN MODELS WERE
SHOWING YESTERDAY.

A STRONG 700MB JET OVER 75KTS WILL PUSH IN SUNDAY MORNING, WITH
STRONG WINDS EXPECTED TO MIX DOWN INTO THE VALLEYS OF NORTHEASTERN
CALIFORNIA AND WESTERN NEVADA. PRESSURE GRADIENTS ARE ALSO
APPROACHING EXTREMES FOR SUNDAY, MEANING ANOTHER HIGH WIND EVENT IS
LIKELY. PACIFIC MOISTURE WILL COMBINE WITH THIS STORM TO PRODUCE
HEAVY PRECIPITATION RATES IN THE SIERRA, AS WELL AS GOOD SPILLOVER
INTO WESTERN NEVADA. SOMETHING OF CONCERN ON SUNDAY WILL BE THE
STRONG WINDS IN THE SIERRA AND HEAVY SNOW COMBINING FOR DANGEROUS
WHITE OUT CONDITIONS. ANYONE WITH TRAVEL PLANS OVER THE SIERRA ON
SUNDAY CHECK BACK FOR LATEST FORECAST CONDITIONS AS WE GET CLOSER.

CURRENT FORECAST FOR SUNDAY STILL HAS ROUGHLY 10 TO 20 INCHES OF
SNOW ALONG THE SIERRA CREST FROM TAHOE DOWN TO MONO COUNTY, WITH 4
TO 10 INCHES BELOW 7000 FEET. WHILE SPILLOVER INTO WESTERN NEVADA
LOOKS GOOD, THE COLD AIR MAY BE PUSHING IN AT THE TAIL END OF THE
PRECIPITATION, WHICH WOULD LEAD TO A MIX OF RAIN/SNOW AND LESS
SNOWFALL IN WESTERN NEVADA THAN IF THE STORM CAME THROUGH AT NIGHT.
STILL, A COUPLE OF INCHES MAY BE POSSIBLE DOWN TO THE VALLEYS OF
WESTERN NEVADA SUNDAY EVENING THAT MAY CAUSE SOME IMPACTS SUNDAY
NIGHT AS WELL AS INTO THE MONDAY MORNING COMMUTE.

LIGHT SNOW SHOWERS WILL LINGER INTO MONDAY AND MONDAY NIGHT AS THE
LOW PUSHES OUT OF THE REGION. BELOW NORMAL TEMPERATURES ARE EXPECTED
THROUGH NEXT WEEK UNDER NORTH FLOW. HOON

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