Winter Weather in Nevada, December 30, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
936 PM PST MON DEC 29 2014

.UPDATE...
JUST A FEW MINOR FORECAST TWEAKS THIS EVENING. WE ARE STILL ON
TRACK FOR A LIGHT SNOWFALL LATER TONIGHT. HOWEVER, THE INITIAL
BAND ASSOCIATED WITH SHALLOWER LIFT/MOISTURE HAS MOVED TO BETWEEN
RENO AND CARSON CITY AND IS NOT THE MAIN BAND OF SNOW FOR THE
AREA.

THE MAIN EVENT FOR THE RENO-SPARKS AND CARSON CITY-MINDEN AREAS
LOOKS TO BE LATER TONIGHT AS THE MAIN UPPER COLD POOL/TROUGH AXIS
APPROACHES. THIS IS EVIDENCED BY INCREASING RADAR RETURNS UP AROUND
PYRAMID LAKE AND COLDER CLOUD TOPS IN THE INFRARED SATELLITE NORTH
OF RENO. ALONG WITH A LIGHT SNOWFALL FOR MOST OF WESTERN NEVADA,
THE INSTABILITY AND DEEPER MOISTURE WITH THE COLD POOL SHOULD
COMBINE WITH UPSLOPE FLOW AGAINST THE CARSON RANGE TO PRODUCE
LOCALLY HIGHER SNOWFALL TOTALS IN THE FOOTHILLS SOUTH AND WEST OF
RENO. SNYDER

&&

.SYNOPSIS...
A STRONG COLD FRONT WILL PUSH THROUGH THE AREA TONIGHT. SNOWFALL IS
POSSIBLE WITH POTENTIAL TRAVEL IMPACTS FOR THE TUESDAY MORNING
COMMUTE ALONG THE HIGHWAY 395 CORRIDOR. STRONG WINDS ARE EXPECTED TO
PRODUCE ROUGH CONDITIONS ON AREA LAKES ALONG WITH POSSIBLE AREAS OF
BLOWING SNOW. TEMPERATURES WILL BE BITTER COLD WITH WIND CHILLS IN
THE SINGLE DIGITS AND NEGATIVE VALUES HEADING INTO THE NEW YEAR. A
MILDER PATTERN WILL RETURN FOR THE WEEKEND.

&&

.PREVIOUS DISCUSSION... /ISSUED 242 PM PST MON DEC 29 2014/

SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT

VISIBLE SATELLITE IMAGERY SHOWING A COLD UPPER LOW ACROSS THE
PACIFIC NORTHWEST WITH COOLING IR COLD TOPS ALONG A STRONG COLD
FRONT OVER SOUTHERN OREGON. THIS FRONT WILL QUICKLY DRIVE SOUTH
THROUGH NORTHERN NEVADA TONIGHT INTO TUESDAY MORNING PROVIDING THE
POTENTIAL FOR A FEW INCHES OF SNOWFALL AND BITTER COLD HEADING INTO
THE NEW YEAR.

HI-RES MESOSCALE AND GLOBAL MODELS ARE BEGINNING TO CLUE INTO THE
FORMATION OF BANDED SNOWFALL CREATED BY STRONG LOW LEVEL
FRONTOGENESIS AND MOISTURE IN A REGION OF FAVORABLE MICROPHYSICS FOR
ICE CRYSTAL GROWTH. THESE COLD TEMPERATURES WILL MAKE FOR LIGHT
AND FLUFFY SNOW. SOME DISAGREEMENT ON TIMING BUT LARGELY LOOKING
FOR SNOWFALL IN THE RENO/CARSON CITY REGION AS EARLY 8PM BUT THE
MOST FAVORABLE WINDOW LOOKS TO BE BETWEEN 10PM-4AM. A WINTER
WEATHER ADVISORY HAS BEEN POSTED FOR THE SIERRA FRONT WHICH
INCLUDES THE HWY 395 CORRIDOR SOUTH THROUGH MINDEN AND
GARDNERVILLE. THE ADVISORY ALSO COVERS PORTIONS OF WESTERN MINERAL
AND SOUTHERN LYON COUNTY. GENERALLY LOOKING FOR SNOWFALL IN THE
1-2" RANGE FROM RENO TO CARSON CITY WITH HIGHER AMOUNTS SOUTH
WHERE UPSLOPE FORCING WILL ADD ADDITIONAL LIFT. LOCATIONS ALONG
THE EASTERN SLOPES OF THE CARSON RANGE, EASTERN ALPINE CO,
NORTHERN MONO COUNTY COULD SEE MORE IN THE 2-4" RANGE. SLIDERS ARE
NOTORIOUSLY DIFFICULT SYSTEMS TO FORECAST SO WILL PUT FORECAST
CONFIDENCE IN SNOW AMOUNTS IN THE MEDIUM CATEGORY.

THE OTHER IMPACTS WITH THIS SYSTEM WILL BE SOME GUSTY CONDITIONS
BEHIND THE FRONT AS A STRONG PRESSURE GRADIENT DEVELOPS ACROSS
WESTERN NEVADA AND THE SIERRA. EXPECTING TO SEE SUSTAINED WINDS IN
THE 15-25 MPH RANGE WITH GUSTS UP TO 40-45 MPH OUT OF THE EAST WHICH
PUTS THIS JUST BELOW ADVISORY CRITERIA ACROSS WESTERN NEVADA. HAVE
HOWEVER POSTED A LAKE WIND ADVISORY FOR PYRAMID LAKE AND A WIND
ADVISORY ACROSS THE TAHOE BASIN. EXPECTING HAZARDOUS BOATING
CONDITIONS ON AREA LAKES WITH GUSTS NEAR 45 MPH EXPECTED IN THE
TAHOE BASIN WITH HIGHEST WAVES ALONG THE ATYPICAL WESTERN SHORES.
WINDS WILL SHARPLY INCREASE IN ELEVATION WITH VERY STRONG WINDS
EXPECTED MAINLY ABOVE 8,500 FEET WHERE GUSTS BETWEEN 80-100+ MPH ARE
POSSIBLE. THIS MAY ALSO POSE THE RISK FOR TREE FALLS ACROSS THE
TAHOE BASIN PARTICULARLY FOR TREES WEAKENED FROM THE PAST WIND
EVENT. THE SAME STRONG WINDS HOLD TRUE ACROSS HIGH TERRAIN THROUGH
MONO COUNTY BUT THE STRONGEST WINDS WILL REMAIN OVER THE CREST AND
ALONG THE WESTERN SLOPES OF THE SIERRA WHERE VERY STRONG DOWNSLOPE
WINDS LOOK FAVORABLE.

OTHERWISE, LOOKING FOR SNOW SHOWERS TO LINGER THROUGH TUESDAY
AFTERNOON ESPECIALLY ACROSS ALPINE AND MONO COUNTY WHERE UPSLOPE
FORCING SETS UP. AN INCH OR TWO IS POSSIBLE ACROSS THE TAHOE BASIN
AND MONO COUNTY OUTSIDE OF AREAS OF LAKE ENHANCED SNOWFALL. STRONG
WINDS MAY ALSO PRODUCE AREAS OF BLOWING SNOW AND REDUCED VISIBILITY.
FUENTES

(WEDNESDAY AND THURSDAY)..
MAIN CHANGE TO THE WEDNESDAY-THURSDAY TIME FRAME WAS LOWERING MAX
AND MIN TEMPS BY A FEW DEGREES EACH, WITH THE INCREASED
EXPECTATION OF ACCUMULATING SNOW WITH THE UPPER LOW PASSING
THROUGH TONIGHT AND TUESDAY. THE PRESENCE OF SNOW COVER WILL
STRENGTHEN THE VALLEY INVERSION FURTHER AND KEEP HIGHS ONLY IN THE
LOWER-MID 20S WEDNESDAY. STRONG NE-E WINDS WILL CONTINUE OVER THE
SIERRA RIDGES WITH GUSTS 75-85 MPH, WHILE SURFACE WIND GUSTS WILL
GENERALLY RANGE FROM 25-35 MPH EXCEPT NEAR 40 MPH AROUND TAHOE
WEDNESDAY MORNING. THESE WINDS WILL DECREASE LATER IN THE DAY AS
THE UPPER LOW MOVES FROM SOUTHEAST CA TO ARIZONA.

NEW YEARS EVE WILL BE QUITE COLD WITH TEMPERATURES BY MIDNIGHT
DROPPING TO THE LOWER TEENS FOR RENO-CARSON CITY AND SINGLE DIGITS
AROUND TAHOE. ALTHOUGH WINDS WILL BE DECREASING, WIND CHILLS COULD
STILL BE NEAR ZERO FOR WESTERN NV AND -10 DEGREES IN THE TAHOE BASIN
FOR THE FIRST COUPLE HOURS OF 2015. THE EARLY MORNING LOWS FOR NEW
YEARS DAY ARE LIKELY TO BE AROUND 5 DEGREES FOR URBAN AREAS OF
WESTERN NV, AND BELOW ZERO AWAY FROM THE MAIN CITIES AND IN THE
SIERRA VALLEYS.

ON THURSDAY, THE CORE OF THE COLD AIR MASS WILL MOVE AWAY FROM
WESTERN NV BUT WITH INVERSION STILL IN PLACE, HIGHS ARE LIKELY TO
REMAIN BELOW FREEZING. LIGHTER WINDS ARE EXPECTED WITH DRY
CONDITIONS PREVAILING THROUGH THE FIRST DAY OF 2015. MJD

LONG TERM (FRIDAY-MONDAY)...

THE MOTTO FOR THE LONG TERM WILL BE "WELCOME TO INVERSION CITY".
GUIDANCE CONSENSUS SHOWS RIDGING JUST OFF THE WEST COAST THROUGH THE
WEEKEND WHICH YIELDS WARMING TEMPERATURES AT 700MB. COUPLED WITH A
SURFACE HIGH OVER THE INTERMOUNTAIN WEST THIS RESULTS IN AN
INVERSION PATTERN FOR THE VALLEYS OF WESTERN NV AND NORTHEAST CA,
WITH LIGHT WINDS, LIMITED MIXING, AND POTENTIAL AIR POLLUTION
BUILDUPS. TEMPERATURES IN VALLEYS WILL WARM EACH DAY BUT AT A MUCH
SLOWER RATE COMPARED TO THE MOUNTAINS. IF WE GET SUFFICIENT SNOWFALL
TONIGHT THEN THOSE INVERSIONS COULD BE STRONGER WITH POTENTIAL FOR
SPOTS OF FREEZING FOG IN NORMALLY PRONE AREAS.

UNFORTUNATELY I'M REALLY NOT SEEING MEANINGFUL STORM POTENTIAL
THROUGH AT LEAST MONDAY AS THE RIDGE BLOCKS PACIFIC STORMS FROM
IMPACTING CA/NV. THERE ARE SOME SIGNS OF THE RIDGE BREAKING DOWN OR
BEING UNDERCUT MID/LATE NEXT WEEK ALLOWING AN INCREASED CHANCE OF
ATMOSPHERIC RIVERS LANDFALLING ON THE WEST COAST. BUT OF COURSE
PREDICTABILITY OF THESE PATTERN CHANGES 7-10 DAYS OUT IS QUITE
LIMITED. CS

AVIATION...

FORECAST CONFIDENCE IN TODAY'S TAFS IS MEDIUM, WITH UNCERTAINTIES IN
TIMING AND INTENSITY OF TONIGHT'S BAND OF SNOW. THESE KIND OF SLIDER
STORMS ARE A CHALLENGE TO PREDICT SO SNOWFALL POTENTIAL REMAINS ONLY
MEDIUM CONFIDENCE AS WELL. HIGH RESOLUTION SIMULATIONS (HRRR) ARE
SHOWING A FAST MOVING BAND OF -SN DEVELOPING FROM AAT-LOL AROUND
SUNDOWN AND THEN DROPPING SOUTHWARD INTO RNO/CXP 4-10Z, TRK/TVL/MEV
AROUND 6-12Z, AND AFTER 12Z AT MMH. IN SUCH A STRONGLY FORCED
SITUATION THE HRRR USUALLY DOES REASONABLY WELL SO WE'LL FOLLOW FOR
THE TAFS.

PERIODS OF MVFR/IFR -SN LIKELY AT RNO/CXP/TRK/TVL/MEV TONIGHT
YIELDING UP TO 2 INCHES OF FLUFFY SNOW. THERE'S ABOUT A 20% CHANCE
WE COULD SEE BRIEF PERIODS OF HEAVIER SNOW, 1/2SM VISIBILITY TYPE
STUFF, BUT PREDICTING TIMING ON THAT IS TRICKY. GUSTY N/NE WINDS
WILL RESULTING IN BLOWING SNOW AS WELL. CLOUDS WILL RESULT IN
TERRAIN OBSCURATION TONIGHT THROUGH TOMORROW.

THE POST-FRONTAL NORTHEAST WINDS TUESDAY WILL BE PRONOUNCED AND
GUSTY, WITH A FRESH SUSTAINED 15-25 KTS EAST/NORTHEAST WIND WITH
GUSTS 25-30 KTS. CXP WHICH IS PRONE TO NE FLOW EVENTS, WILL LIKELY
SEE PERIODS OF STRONGER SUSTAINED WINDS. RIDGE LEVEL GUSTS OF 60-70
KTS FORECAST TOMORROW, INCREASING TUESDAY NIGHT INTO WEDNESDAY. DUE
TO THE UNUSUAL NE WIND DIRECTION, THAT WILL LEAD TO TURBULENCE
ESPECIALLY WEST OF ANY MOUNTAINS DUE TO MOUNTAIN WAVE ACTIVITY. CS

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY FROM 7 AM TO 7 PM PST TUESDAY FOR PYRAMID
     LAKE IN NVZ004.

     WIND ADVISORY FROM 7 AM TUESDAY TO 4 AM PST WEDNESDAY NVZ002.

     WINTER WEATHER ADVISORY UNTIL 4 PM PST TUESDAY NVZ001.

     WINTER WEATHER ADVISORY UNTIL 10 AM PST TUESDAY NVZ003.

CA...WIND ADVISORY FROM 7 AM TUESDAY TO 4 AM PST WEDNESDAY CAZ072.

&&

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