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070
FXUS65 KREV 171735
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
935 AM PST WED DEC 17 2014

.UPDATE...
CLOUDS HAVE THINNED A BIT MORE THAN FORECAST EAST OF THE SIERRA
TODAY WHILE SHOWERS ARE NOT QUITE AS WIDESPREAD IN THE SIERRA NOW.
HAVE REDUCED CLOUD COVER AND POPS EAST OF THE SIERRA FOR THE REST
OF THE DAY. THERE ARE SHOWERS WORKING THEIR WAY INTO THE WESTERN
SLOPES OF THE SIERRA NOW. THESE ARE IN MOIST FLOW BETWEEN AN
EXITING SHORT WAVE MOVING INTO NEVADA AND AN APPROACHING WAVE
MOVING TOWARD THE CA COAST. SHOWERS SHOULD INCREASE IN COVERAGE
LATER THIS AFTERNOON IN THE SIERRA AND NORTHEAST CA IN RESPONSE TO
THIS APPROACHING WAVE. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 401 AM PST WED DEC 17 2014/

UPDATE...

QUICK UPDATE THIS MORNING TO INCLUDE SOME LAKE EFFECT SNOW SHOWERS
DEVELOPING OFF OF LAKE TAHOE. THE LIGHT SNOW BAND IS AROUND MOUNT
ROSE AND JUST NORTH OF WASHOE VALLEY. LIGHT SNOW ACCUMULATIONS
COULD MAKE FOR SOME SLICK DRIVING CONDITIONS THIS MORNING ON MOUNT
ROSE HIGHWAY AND I-580 BETWEEN RENO AND CARSON CITY. HOON

PREVIOUS DISCUSSION... /ISSUED 304 AM PST WED DEC 17 2014/

SYNOPSIS...

A WEAK SYSTEM EXITS THE REGION TODAY WITH RESIDUAL SHOWERS EXPECTED
ACROSS THE SIERRA AND PORTIONS OF NORTHEAST CALIFORNIA. ANOTHER WEAK
SYSTEM WILL PUSH INTO THE SIERRA AND WESTERN NEVADA TONIGHT BRINGING
THE NEXT ROUND OF LIGHT SNOW SHOWERS FOR THE HIGHER TERRAIN. SLICK
AND SNOW COVERED ROADS WILL IMPACT THE SIERRA PASSES THROUGH
FRIDAY.

SHORT TERM...
WEAK DISTURBANCE CURRENTLY MAKING ITS WAY ACROSS CALIFORNIA EARLY
THIS MORNING. A STRONGER JET AND SYSTEM UPSTREAM IS DIVING SOUTH AND
BREAKING UP/SPLITTING THE ENERGY WITH THIS FIRST WAVE AS IT
ENCOUNTERS THE SIERRA. THIS IS RESULTING IN THE BAND OF RAIN/SNOW
SHOWERS NEAR THE SIERRA TO FALL APART EARLY THIS MORNING, WITH
WARMING CLOUD TOPS ALSO INDICATING THE WEAKENING OF THE BAND. THE
BEST CHANCES FOR PRECIPITATION WILL BE SOUTH OF HIGHWAY 50 AS THE
SYSTEM CONTINUES TO GET SHOVED FURTHER SOUTH OF THE LAKE TAHOE
BASIN.

RESIDUAL SHOWERS WILL CONTINUE WITH MOIST UPSLOPE FLOW ACROSS
NORTHEASTERN CALIFORNIA AND THE SIERRA TODAY. THE LACK OF DYNAMICS
AND STRONG SOUTHWEST FLOW WILL RESULT IN MUCH OF THE PRECIPITATION
BEING SHADOWED OUT FOR WESTERN NEVADA THROUGH THE DAY, ALTHOUGH SOME
WEAK FLURRIES WILL BE POSSIBLE. THE NEXT WAVE WILL SWING THROUGH
THE AREA THIS EVENING INTO THURSDAY MORNING, BRINGING ANOTHER
ROUND OF LIGHT SNOW SHOWERS TO THE SIERRA. MAIN IMPACT WILL
CONTINUE TO BE INTERMITTENT DETERIORATING ROAD CONDITIONS ACROSS
SIERRA AND MOUNTAIN PASSES AS SNOW SHOWERS MOVE THROUGH THE REGION
THROUGH THURSDAY. KEEP UPDATED WITH ROAD CONDITIONS VIA NDOT AND
CALTRANS THROUGH THE END OF THE WEEK.

SHORTWAVE RIDGING WILL GIVE THE REGION A SHORT REPRIEVE FROM
PRECIPITATION WITH CLEARING SKIES AND LIGHT WINDS. THE NEXT SYSTEM
DROPS OUT OF THE GULF OF ALASKA AND ADVANCES TOWARDS THE REGION ON
FRIDAY AFTERNOON. NAM/ECMWF/GFS ALL HAVE SIMILAR TIMING WITH THE
COLD FRONT SWEEPING ACROSS THE REGION ON FRIDAY AFTERNOON. LIGHT
RAIN AND MOUNTAIN SNOW ARE LIKELY BY FRIDAY AFTERNOON, MAINLY NORTH
OF THE TAHOE BASIN AND INTERSTATE 80. PRECIPITATION AMOUNTS REMAIN
MODEST AT THIS TIME, AS JET ORIENTATION WILL NOT PROMOTE THE
DYNAMICS NEEDED FOR HIGHER AMOUNTS. STILL LOOKING AT AROUND A 0.10
TO 0.2 INCHES FROM PLUMAS-LASSEN-MODOC COUNTIES. THERE IS ALSO THE
POSSIBILITY THAT THE STRONG NORTH-SOUTH ORIENTED JET MAY RESULT IN
THE BULK OF THE SYSTEM`S DYNAMICS AND PRECIPITATION BEING DRIVEN
FURTHER SOUTH. OVERALL THIS IS NOT AN INCREDIBLY STRONG STORM, BUT
IT COULD BRING ANOTHER ROUND OF SNOW RESULTING IN CONTINUED WINTRY
ROAD CONDITIONS FOR THE SIERRA AND HIGHER TERRAIN. WEISHAHN

LONG TERM...SATURDAY THROUGH CHRISTMAS EVE...

BY SATURDAY, AN UPPER LEVEL RIDGE STARTS TO BUILD OVER THE
CALIFORNIA COAST. THIS LOOKS TO BE A DIRTY RIDGE, DUE TO WARM AIR
ADVECTION MOISTURE STREAMING INTO THE PACIFIC NORTHWEST AND CLIPPING
FAR NORTHERN CA/NV. THIS WILL KEEP SOME CLOUDS AROUND THROUGH THE
WEEKEND WITH CHANCES OF LIGHT RAIN/SNOW ON SATURDAY. MODELS ARE IN
GOOD AGREEMENT THAT THE RIDGE WILL AMPLIFY AS WE GO INTO NEXT WEEK,
BRINGING MILD AND DRY CONDITIONS. LIGHT WINDS AND VALLEY INVERSIONS
WILL ALSO LIKELY BRING AIR QUALITY ISSUES FOR EARLY NEXT WEEK AS
WELL. HOON

AVIATION...

LIGHT SNOW SHOWERS CONTINUE IN THE SIERRA THIS MORNING WITH MVFR CIG
FOR KTRK/KTVL/KMMH. LITTLE TO NO ACCUMULATION EXPECTED AS THIS STORM
WILL REMAIN MAINLY WEST OF THE SIERRA CREST. FOR KRNO/KCXP...A FEW
SHOWERS ARE POSSIBLE THIS MORNING, BUT RESTRICTIONS TO CIG/VIS ARE
UNLIKELY. MOUNTAIN OBSCURATION AND LIGHT TURBULENCE/ICING ARE ALSO
EXPECTED FOR TODAY. HOON

&&

.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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