Strong Wind in Nevada, January 9 to 10, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
243 PM PST WED JAN 9 2013

.SYNOPSIS...
A STRONG COLD FRONT WILL MOVE THROUGH THE EASTERN SIERRA AND
WESTERN NEVADA TONIGHT. WINDS WILL REMAIN GUSTY AHEAD OF THE FRONT
WITH SOME LOCALLY HEAVY SNOW BEHIND THE FRONT. MUCH COLDER
TEMPERATURES WILL CONTINUE INTO THE WEEKEND BEHIND THE FRONT UNDER
COLD NORTH FLOW WITH A FEW SNOW SHOWERS CONTINUING INTO FRIDAY.

&&

.SHORT TERM...
ADVERTISED STRONG COLD FRONT IS NOW INTO NORTHERN CALIFORNIA AND
SNOW HAS STARTED ACROSS WESTERN LASSEN COUNTY. MODELS CONTINUED
THEIR TREND WETTER FOR TONIGHT AND MADE SOME ADJUSTMENTS TO THE
FORECAST BASED ON THESE IDEAS. EVEN THE DRIER NAM HAS COME MUCH
MORE IN LINE WITH THE WETTER GFS/EC. BEYOND TONIGHT, MODELS KEEP
THE COLD AIR MASS IN PLACE WITH MUCH BELOW NORMAL TEMPERATURES
INTO THE WEEKEND.

APPROXIMATE FRONTAL PASSAGE TIMES ARE 4-6 PM FOR SUSANVILLE-
CEDARVILLE, 10 PM TO MIDNIGHT FOR THE I-80 CORRIDOR AND 4 AM FOR
BRIDGEPORT-HAWTHORNE. AHEAD OF THE FRONT, WINDS ARE GUSTY ALONG THE
395/I-580 CORRIDOR AND EXPECT THESE WINDS TO CONTINUE UNTIL
FRONTAL PASSAGE. CURRENT WIND ADVISORIES LOOK GOOD AS THE SIERRA
FRONT IS SEEING GUSTS 40-50 MPH WITH LOCAL GUSTS TO 60 MPH. EXPECT
THESE WINDS TO SPREAD SOUTH THIS EVENING. BEHIND THE FRONT, WINDS
WILL WEAKEN BUT STILL REMAIN LOCALLY GUSTY.

FOR SNOWFALL BEHIND THE FRONT, EXPECT SNOW LEVELS TO RAPIDLY REACH
THE VALLEY FLOORS. THERE MAY BE A BRIEF MIX WITH RAIN BELOW 5000
FEET AT PRECIP ONSET, BUT IT SHOULD NOT LAST MORE THAN 30 MINUTES
OR SO BEFORE COMPLETE CHANGEOVER. WITH MODELS NOW ADVERTISING 1/4
TO 1/2 INCH FROM BOGARD THROUGH NORTHERN WASHOE COUNTY, UPGRADED
THE ADVISORY TO A WARNING THERE. LIKE THE WETTER MODEL IDEAS AT
THIS TIME AS THE FORCING JUST BEHIND THE FRONT IS IMPRESSIVE WITH
GOOD LIFT THROUGH THE DENTRITIC LAYER. WITH SUCH GOOD FORCING,
SPILLOVER SHOULD OCCUR SO EXPECT 3-5 INCHES ACROSS THE LOWER
ELEVATIONS WITH HIGHER AMOUNTS FOR WESTERN LASSEN COUNTY.

FURTHER SOUTH, THE WETTER SOLUTION AND STRONG FORCING TO I-80 LEAD
ME TO BELIEVE THERE WILL BE ACCUMULATING SNOWS NOT ONLY FOR THE
TAHOE BASIN BUT INTO WESTERN NV AS WELL. EXPECT A 2-3 HOURS BURST
OF SNOW TONIGHT WITH ACCUMULATIONS ROUGHLY 2 INCHES OR SO LESS
THAN WHAT WILL OCCUR FURTHER NORTH. THE GREATEST ACCUMULATION WILL
OCCUR DURING THE EARLY MORNING HOURS WITH ANOTHER LIGHTER BURST
AROUND SUNRISE. HAVE RUN THE ADVISORY THROUGH THE MORNING RUSH
HOUR AS ROADS WOULD LIKELY REMAIN SLICK AND ICY THROUGH THE TIME
DUE TO THE VERY COLD TEMPERATURES BEHIND THE FRONT.

FOR THURSDAY AND FRIDAY, COLD, NORTH, UNSTABLE FLOW WILL REMAIN.
THE GREATEST INSTABILITY WILL OCCUR THURSDAY WITH SCATTERED SNOW
SHOWERS BECOMING ISOLATED FRIDAY. SOME LAKE ENHANCEMENT IS LIKELY
DOWNSTREAM OF THE MAJOR LAKES ESPECIALLY THURSDAY EVENING.
HOWEVER, IT DOES NOT LOOK TO BE A MAJOR EVENT AS THE WINDS ALOFT
ARE 30 KTS AT 700 MB AND THIS WILL ACT TO SHEAR THE CONVECTIVE
COLUMNS.

OUTSIDE OF THE SNOW, IT WILL BE VERY COLD THE NEXT FEW DAYS WITH
HIGHS AS MUCH AS 30 DEGREES COLDER THURSDAY THAN THEY WERE TODAY.
HIGHS WILL STRUGGLE TO BREAK 30 IN WESTERN NEVADA WITH WIDESPREAD
TEENS AND 20S IN THE SIERRA. OVERNIGHT LOWS WILL BE BELOW ZERO IN
MANY SIERRA VALLEYS ALSO. DESPITE THIS COLD AIR MASS AND SNOW ON
THE GROUND, THE STRONG INVERSIONS OF THE PAST WEEK ARE NOT
EXPECTED TO FORM THROUGH THE WEEKEND AS THE TEMPERATURES ALOFT ARE
ALSO VERY COLD. WALLMANN

.LONG TERM...SUNDAY THROUGH WEDNESDAY...
VERY LITTLE HAS CHANGED WITH THE EXPECTED CONDITIONS IN THE
EXTENDED FORECAST. THEREFORE, ONLY VERY MINOR ADJUSTMENTS WERE
MADE TO THE EXISTING PRODUCT. MODELS REMAIN IN CONSENSUS THAT A
VERY HIGHLY AMPLIFIED RIDGE WILL PERSIST OFF SHORE THROUGHOUT THE
FORECAST PERIOD WITH BROAD TROUGHING AND SEASONABLY COLD
TEMPERATURES OVER MUCH OF THE WESTERN UNITED STATES.

WITH THE RIDGE EXTENDING THROUGH THE GULF OF ALASKA INTO THE ALASKAN
INTERIOR, COLD AIR WILL CONTINUE TO FUNNEL INTO THE REGION FROM
NORTHERLY FLOW. ANOTHER REINFORCING PUNCH OF COLDER TEMPERATURES
WILL OCCUR SATURDAY AS A WEAK IMPULSE PUSHES THROUGH THE REGION
SUNDAY. HAVE LOWERED TEMPERATURES A LITTLE EACH DAY ESPECIALLY FOR
PERSHING AND CHURCHILL COUNTIES WHERE MODELS SHOW -20C TEMPERATURES
AT 700MB MOVING THROUGH. ANTICIPATE INVERSIONS TO STRENGTHEN THROUGH
MID WEEK AS UPPER AND MID SLOPES WARM WHILE COLD AIR BECOMES TRAPPED
IN VALLEYS. WARMING IN LOW LEVELS WILL DEPEND ON PRECIPITATION THAT
MAY RESULT FROM THIS SLIDER TYPE SYSTEM.

THERE HAS BEEN A LARGE AMOUNT OF UNCERTAINTY WITH THIS SYSTEM. THE
GFS HAS BEEN DRY OVER THE LAST FOUR DAYS WHILE THE EC AND GEM
STARTED MUCH WETTER THEN TRENDED DRY OVER THE LAST COUPLE OF RUNS.
NOW THE GFS AND NAM ARE SHOWING SOME MOISTURE. KEPT SLIGHT CHANCES
OF SNOW WITH THIS SLIDER SYSTEM BASED OFF MODEL INCONSISTENCY, BUT
WILL ADJUST TO LOW CHANCE WORDING IF GFS AND NAM CONTINUE WITH
MOISTURE OVER THE NEXT COUPLE OF RUNS. BOYD

&&

.AVIATION...
FLYING CONDITIONS WILL INITIALLY BE IMPACTED BY A PASSING SYSTEM
EARLY IN THE EVENING. MAINLY SNOW SHOWERS BECOME LESS FREQUENT
OVERNIGHT WITH SOME LINGERING IN THE SIERRA AT KTRK AND KTVL INTO
THE EARLY MORNING HOURS. SOUTHERLY WINDS BECOMING WESTERLY LATE IN
THE EVENING AND THEN NORTHWESTERLY BEHIND THE FRONT OVERNIGHT. IN
BETWEEN PERIODS OF PRECIPITATION, WINDS MAY BE QUITE GUSTY WITH
GUSTS GENERALLY AROUND 35 KNOTS AND UP TO 50 MPH POSSIBLE. LOW
LEVEL WIND SHEAR WILL ALSO BE A THREAT, ESPECIALLY FOR WESTERN
NEVADA LOCATIONS WHERE TERRAIN DRIVES SOUTHERLY FLOW WHILE WINDS
ALOFT WILL BE FROM THE SOUTHWEST.

CONDITIONS IMPROVE TO MAINLY VFR THROUGH THE DAY AS SNOW TAPERS OFF
AND GRADIENT WINDS SLOW AFTER MIDNIGHT. A FEW SNOW SHOWERS WILL
CONTINUE TO BE POSSIBLE FOR SIERRA LOCATIONS, BUT THEY WILL BECOME
FEWER AND FARTHER IN BETWEEN. ASIDE FROM A WEAK SYSTEM BRINGING
ISOLATED SNOW SHOWERS SUNDAY, COLD HIGH PRESSURE BUILDS IN ACROSS
THE REGION. BOYD
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...WINTER STORM WARNING UNTIL 9 AM PST THURSDAY NVZ005.

     WIND ADVISORY UNTIL 4 AM PST THURSDAY NVZ001.

     LAKE WIND ADVISORY UNTIL 6 PM PST THIS EVENING FOR LAKE TAHOE IN
     NVZ002.

     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM PST
     THURSDAY NVZ002.

     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 9 AM PST
     THURSDAY NVZ003-004.

     WIND ADVISORY UNTIL 10 PM PST THIS EVENING NVZ003.

     LAKE WIND ADVISORY UNTIL 6 PM PST THIS EVENING FOR PYRAMID LAKE
     IN NVZ004.

CA...WINTER STORM WARNING UNTIL 9 AM PST THURSDAY CAZ070-071.

     WIND ADVISORY UNTIL 4 AM PST THURSDAY CAZ073.

     LAKE WIND ADVISORY UNTIL 6 PM PST THIS EVENING FOR LAKE TAHOE IN
     CAZ072.

     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM PST
     THURSDAY CAZ072.

&&

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