Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 151117
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
317 AM PST MON DEC 15 2014

.SYNOPSIS...

A SERIES OF WEATHER SYSTEMS WILL BRING PERIODS OF SNOW TO THE
SIERRA AND WESTERN NEVADA THIS WEEK. ALTHOUGH HEAVY SNOW IS NOT
EXPECTED THROUGH MIDWEEK, SLICK DRIVING CONDITIONS COULD AFFECT
LOWER ELEVATIONS AND IMPACT THE PEAK MORNING AND EVENING COMMUTE
TIMES FROM TODAY THROUGH WEDNESDAY.

&&

.SHORT TERM...

AREA OF PRECIP OVER CENTRAL CALIFORNIA CONTINUES TO SPREAD
NORTHEAST EARLY THIS MORNING. FORECAST SOUNDINGS AROUND RENO AND
TAHOE INDICATE DEEP MOISTURE AND INCREASING LIFT THIS MORNING IN
THE 600-500 MB LAYER, WHICH IS LOCATED AT A TEMPERATURE RANGE
FAVORABLE FOR SNOW GROWTH DUE TO MICROPHYSICS. THE 00Z GFS AND
ECMWF PRECIP FIELDS APPEARED TO BE MORE IN LINE WITH THE MODEL
SOUNDINGS, WHICH INDICATED A PERIOD OF SNOW SPREADING INTO TAHOE
AND FAR WESTERN NV AFTER 12Z, WITH PEAK COVERAGE AND INTENSITY
COINCIDING WITH THE MORNING COMMUTE.

THE SNOW THAT FALLS THIS MORNING WILL LIKELY RESEMBLE THE
ACCUMULATION CHARACTER OF THE SNOW WHICH OCCURRED LATE SUNDAY
AFTERNOON IN WESTERN NV. BELOW 5000 FEET, ACCUMULATIONS SHOULD BE
MAINLY LIMITED TO UNPAVED SURFACES, ALTHOUGH A FEW SLICK PATCHES
ARE POSSIBLE ON BRIDGES/OVERPASSES. ROAD SURFACE TEMPERATURES IN THE
LOWER VALLEYS AROUND RENO-CARSON CITY ARE GENERALLY EXPECTED TO
REMAIN ABOVE FREEZING. AREAS ABOVE 5000 FEET COULD RECEIVE AROUND
1 INCH OF SNOW WITH HIGHER POTENTIAL FOR SNOW STICKING TO PAVEMENT.

THIS MORNING SNOW EVENT WILL ALSO AFFECT THE TAHOE BASIN WITH
ACCUMULATIONS UP TO 3 INCHES, AND NORTHEAST CALIFORNIA WITH 1 INCH
OR LESS FROM SUSANVILLE EASTWARD, AND ABOUT 2 INCHES WEST OF
SUSANVILLE. ANYONE DRIVING IN THESE AREAS THIS MORNING SHOULD USE
EXTRA CAUTION AND ALLOW EXTRA TIME TO REACH THEIR DESTINATION.

BY THIS AFTERNOON, THE MAIN PRECIP BAND IS EXPECTED TO LIFT
FARTHER NORTH INTO NORTHWEST NV, BUT IS LESS LIKELY TO PRODUCE
LOWER ELEVATION TRAVEL IMPACTS, DUE TO TEMPERATURES RISING INTO
THE UPPER 30S OR LOWER 40S AT THAT TIME OF DAY.

FOR TONIGHT, ADDITIONAL BANDS OF SNOW OR SNOW SHOWERS ARE LIKELY
TO DEVELOP NEAR THE SIERRA AND SPREAD EAST AS ELONGATED TROUGH
PASSES ACROSS WESTERN NV. UP TO 4 INCHES OF SNOW MAY ACCUMULATE
NEAR THE SIERRA BETWEEN PLUMAS AND MONO COUNTIES INCLUDING THE
TAHOE BASIN. LIGHTER AMOUNTS (GENERALLY 1 INCH OR LESS) COULD
EXTEND INTO THE RENO-CARSON CITY REGION BY LATE TONIGHT AND AGAIN
PRODUCE POSSIBLE SLICK DRIVING CONDITIONS.

ON TUESDAY, A SHORT BREAK IN BETWEEN WEATHER SYSTEMS IS EXPECTED,
ALTHOUGH SOME LIGHT SNOW SHOWERS REMAIN POSSIBLE ESPECIALLY NEAR
THE SIERRA AND INTO NORTHEAST CA.

FOR TUESDAY NIGHT, MODEL GUIDANCE IS COMING IN BETTER AGREEMENT
WITH ANOTHER LOW PRESSURE SPREADING A ROUND OF SNOW ACROSS THE
SIERRA AND INTO PARTS OF WESTERN NV. THIS LOW APPEARS TO BE A BIT
STRONGER AND COLDER THAN ANY OF THE PRECEDING SYSTEMS. IF THIS
STORM TRACK HOLDS TOGETHER, SNOW AMOUNTS MAY MEET WINTER WEATHER
ADVISORY CRITERIA IN SOME AREAS NEAR AND WEST OF HIGHWAY 395.
PRELIMINARY SNOW PROJECTIONS CALL FOR 2-6 INCHES FROM WESTERN
LASSEN COUNTY SOUTHWARD ACROSS THE TAHOE BASIN AND WESTERN MONO
COUNTY, WITH LOCALLY UP TO 8 INCHES NEAR THE CREST. FOR EASTERN
LASSEN COUNTY AND FAR WESTERN NV, 1-3 INCHES OF SNOW ARE POSSIBLE.
HOWEVER, THE MODEL GUIDANCE HAS VARIED WITH THE TRACK OF THIS LOW
SO CONFIDENCE LEVEL IS ONLY MEDIUM FOR THE SIERRA, AND LOW FOR
SNOW AMOUNTS IN THE LOWER ELEVATIONS OF WESTERN NV-NORTHEAST CA.

FOR WEDNESDAY, SNOW WILL TAPER TO ISOLATED-SCATTERED SHOWERS AS
THE MOISTURE FEED AND LOW PRESSURE EXITS INTO SOUTHERN NEVADA.
DRIER AIR WILL LEAD TO THE FINAL LINGERING SHOWERS TAPERING OFF BY
WEDNESDAY NIGHT. MJD

.LONG TERM...THURSDAY THROUGH SUNDAY...

MODELS ARE IN GOOD AGREEMENT FOR THURSDAY, SHOWING SHORTWAVE RIDGING
OVER THE WEST COAST. AFTER THURSDAY, THE MODELS CONTINUE TO SHOW
QUITE A BIT OF DIFFERENCES, LEADING TO LOW FORECASTER CONFIDENCE
REGARDING PRECIPITATION. LOW PRESSURE IS EXPECTED TO DROP OUT OF THE
GULF OF ALASKA LATE IN THE WEEK, THEN PUSH INTO NORTHERN CA/NV ON
FRIDAY. LATEST GFS IS TAKING THE MAJORITY OF THE ENERGY INTO THE
PAC NW AND WASHES OUT THE FRONT AS IT MOVES INTO THE SIERRA.
RECENT TRENDS IN THE GFS ARE SHOWING A DEFINITE SIGNAL OF HIGHER
HEIGHTS OVER CA/NV.

ON THE OTHER HAND, THE MORE CONSISTENT ECMWF DOES LOOK BETTER FOR
OUR AREA, TRACKING THE SHORTWAVE THROUGH NORTHERN CA/NV AND
BRINGING POTENTIAL FOR MORE PRECIP IN THE SIERRA AND WESTERN
NEVADA. FOR NOW, WILL KEEP THE FORECAST CLOSER TO THE ECMWF AS IT
HAS BEEN MORE CONSISTENT OVER THE LAST COUPLE DAYS. TIMING OF THIS
TROUGH DOES LOOK TO HAVE GOOD AGREEMENT, AROUND THE FRIDAY TO
SATURDAY MORNING TIME FRAME FOR POTENTIAL IMPACTS TO TRAVEL IN THE
SIERRA. THERE IS A STRONG SIGNAL OF RIDGING BUILDING BACK INTO THE
REGION OVER THE WEEKEND AS THE STORM TRACK SHIFTS NORTH INTO THE
PACIFIC NORTHWEST. HOON

&&

.AVIATION...

LOW PRESSURE WILL PUSH MOISTURE INTO THE SIERRA AND WESTERN NEVADA
TODAY AND TUESDAY WITH CHANCES FOR SIERRA SNOW AND MIXED RAIN/SNOW
DOWN TO THE WESTERN NEVADA TERMINALS. STRATUS IS ALREADY BRINGING A
MIX OF IFR CONDITIONS TO KTRK AND KCXP AND IS LIKELY TO CONTINUE
THROUGH THE MORNING.

SNOW WILL PUSH INTO THE AREA THIS MORNING, THEN AGAIN LATER THIS
EVENING AFTER 00Z TUE. AS FOR KTRK/KTVL...1-3" OF SNOW ACCUMULATION
CAN BE EXPECTED THROUGH 18Z THIS MORNING, WITH ANOTHER 2-4" POSSIBLE
TONIGHT INTO TUESDAY MORNING. FOR KMMH...TODAY SHOULD REMAIN DRY,
WITH 1-3" POSSIBLE LATE TONIGHT INTO EARLY TUESDAY. AS FOR
KRNO/KCXP...LESS THAN ONE INCH OF SNOW EXPECTED DUE TO WARM GROUND
TEMPERATURES.

WINDS DO NOT LOOK PARTICULARLY STRONG FOR THIS SYSTEM BUT AREAS OF
TURBULENCE POSSIBLE ALONG THE SIERRA WITH GUSTS OVER 40 KTS
EXPECTED. FUENTES/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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