High Wind in California, November 21, 2012

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
1000 PM PST TUE NOV 20 2012

.UPDATE...
NO CHANGES PLANNED THIS EVENING AS FORECAST IS ON TRACK. WINDS ARE
INCREASING ACROSS THE SIERRA FRONT THIS EVENING AS EXPECTED WITH
THE STRONGEST WINDS FORECAST AROUND SUNRISE. WIND ADVISORY FOR
TAHOE/SIERRA FRONT THROUGH TOMORROW MORNING STILL LOOKS GOOD. HIGH
WIND WARNING FOR LASSEN THROUGH NORTHERN WASHOE MAY NOT VERIFY,
BUT WINDS HAVE BEEN AROUND ADVISORY LEVEL THERE AND WILL LEAVE
ALONE TO NOT SEND OUT MIXED MESSAGES.

AS FAR AS PRECIP, SOUNDING PROFILES ARE NOT FAVORABLE FOR
SPILLOVER AND MOST RAINFALL HAS BEEN NEAR THE SIERRA CREST AND IN
WESTERN LASSEN COUNTY. EXPECT ONLY LIMITED SPILLOVER 10-20 MILES
EAST OF THE CREST AND THE FORECAST HANDLES THIS WELL WITH A STRONG
SHADOW IN THE POP GRIDS. SNOW LEVELS ARE AROUND 7000 FEET AND WILL
ONLY FALL A FEW HUNDRED FEET AT BEST THROUGH NOON WEDNESDAY.
RAINFALL TOTALS OF 1/2 TO 1 INCH NEAR THE CREST THAT WILL RAPIDLY
FALL OFF TO THE EAST. ALL THIS IS IN THE FORECAST AS WELL.
WALLMANN

&&

.PREVIOUS DISCUSSION... /ISSUED 207 PM PST TUE NOV 20 2012/

SHORT TERM...

MAIN ISSUE IS TONIGHT AND EARLY WEDNESDAY MORNING AS A COLD FRONT
TRACKS ACROSS NORTHERN CALIFORNIA AND INTO WESTERN NEVADA. AHEAD
OF THE FRONT STRONG AND GUSTY WINDS WILL PERSIST WITH RAIN AND
HIGH ELEVATION SNOW SPREADING INTO WESTERN LASSEN COUNTY SOUTHWARD
TO ALPINE AND NORTHERN MONO COUNTY.

FOR THE WINDS TONIGHT...LITTLE HAS CHANGED IN FORECAST REASONING.
OVERALL PEAK GUSTS OF 55-65 MPH WILL IMPACT THE THE RENO-CARSON-
TAHOE AREA NORTH TO LASSEN AND NORTHERN WASHOE COUNTIES THROUGH
WEDNESDAY MORNING. GUSTY WINDS MAY ALSO IMPACT LYON AND NORTHERN
MONO COUNTIES EARLY WEDNESDAY MORNING. FOR SIMPLICITY HAVE BUMPED
UP THE START TIME OF THE WIND ADVISORIES FOR RENO-CARSON-TAHOE
AND ENDED THE LAKE WIND ADVISORY FOR THE TAHOE BASIN EARLY.

RIDGE WINDS ARE ON THE RISE AND WITH GOOD MIXING, STRONGER GUSTS
NEAR 50 MPH ARE REACHING THE SURFACE. IN ADDITION A STRONG SOUTH
TO NORTH SURFACE PRESSURE GRADIENT WILL HELP PRODUCE SUSTAINED
WINDS AS HIGH AS 40 MPH ACROSS NORTHWEST NEVADA (INCLUDING RENO-
CARSON-DOUGLAS), NORTHEAST CALIFORNIA AND THE SURPRISE VALLEY.
SOUTH TO NORTH GRADIENTS SUPPORT A STRONGER SUSTAINED WIND EVENT
ON THE RENO VALLEY FLOOR THAN IN SOME NEARBY WIND PRONE AREAS. THE
RENO AIRPORT HAS BEEN IMPACTED BY SUSTAINED WINDS NEAR 30 MPH
SINCE EARLY THIS AFTERNOON.

MODELS CONTINUE TO SUPPORT A SHORT DURATION DOWNSLOPE EVENT EARLY
WEDNESDAY MORNING ACROSS WESTERN NEVADA AS THE FRONT PASSES. THIS
MAY BOOST GUSTS A BIT HIGHER BETWEEN 4AM AND 10AM WEDNESDAY MORNING.

RAIN AND HIGH ELEVATION SNOW ALONG THE FRONT HAS REACHED WESTERN
LASSEN AND PLUMAS COUNTIES AND WILL SLOWLY MOVE SOUTH TO THE YUBA
PASS AND TAHOE BASIN THIS EVENING. LACK OF MOISTURE DEPTH WILL
LIMIT THE AMOUNT OF RAIN AND SNOW CROSSING INTO WESTERN NEVADA.
SNOW LEVELS ARE ON THE HIGH SIDE, A PROFILER IN CHICO RECENTLY
REPORTED A SNOW LEVEL NEAR 8000 FEET. DO THINK SNOW LEVELS WILL
DROP DOWN TO 7000-7500 FEET TONIGHT IN THE TAHOE BASIN PERHAPS
A BIT BELOW 7000 FEET ALONG HIGHWAY 89 DUE TO A HIGHER
PRECIPITATION INTENSITY. ACCUMULATIONS ON ROADS WILL BE LIMITED TO
JUST A FEW INCHES ALONG A SHORT STRETCH OF I-80 AND US-50 ABOVE
7000 FEET. THE HIGHEST TOTALS WILL OCCUR ABOVE 8000 FEET WHERE
AMOUNTS OF 4 INCHES OR MORE ARE POSSIBLE.

WINDS REMAIN BREEZY THROUGH WEDNESDAY AFTERNOON WITH PEAK GUSTS
TO 40 MPH BEHIND THE FRONT. HAVE ISSUED A LAKE WIND ADVISORY FOR
PYRAMID LAKE STARTING EARLY WEDNESDAY MORNING.

SNOW SHOWERS MAY LINGER INTO WEDNESDAY AFTERNOON NEAR THE SIERRA
CREST. TRAVEL IMPACTS WILL BE MINIMAL BY WEDNESDAY AFTERNOON AS
THE SHOWERS WILL DIMINISH FOR THE HOLIDAY RUSH OVER THE PASSES.
STILL THOSE TRAVELING WILL WANT TO BE PREPARED FOR WET AND
POSSIBLY SLICK ROADS WEDNESDAY EVENING. AFTER SUNSET TEMPERATURES
WILL DROP OFF AND ANY MELTED SNOW OVER THE PASSES MAY TURN INTO
BLACK ICE.

TEMPERATURES WILL REMAIN A BIT ON THE COOL SIDE FOR THANKSGIVING
DAY, BUT WITH LIGHT WINDS AND SUNNY SKIES. THOSE HEADING OUT
THANKSGIVING NIGHT AND EARLY MORNING FRIDAY WILL WANT TO PREPARE
FOR COLD TEMPERATURES. LOWS WILL DROP INTO THE 20S ACROSS WESTERN
NEVADA, WITH TEENS IN THE COLDER SIERRA VALLEYS. BRONG

LONG TERM...SATURDAY THROUGH TUESDAY...

VERY FEW CHANGES WERE MADE TO THE FORECAST. HIGH PRESSURE BEGINS TO
FLATTEN SATURDAY AS FAST MOVING FLOW PUSHES A SHORTWAVE ACROSS THE
PACIFIC NORTHWEST. MODELS CONTINUE TO TREND WARMER AND DRIER WITH
THIS SYSTEM TAKING IT MORE ON A WEST TO EASTERLY TRAJECTORY THROUGH
THE NORTHERN PLAINS OF THE U.S. RATHER THAN DROPPING THE ENERGY
SOUTH AS SHOWN BY EARLY RUNS. GFS AND ECMWF SHARE THIS CONSENSUS
WHILE THE GEM CONTINUES TO HOLD ON TO A MUCH COLDER SOLUTION. HAVE
REJECTED GEM'S SOLUTION IN FAVOR OF GFS/ECMWF CONSENSUS. CONTINUE TO
HAVE SLIGHT CHANCES OF RAIN SHOWERS SATURDAY INTO SUNDAY ACROSS THE
NORTHERN EDGE OF THE FORECAST REGION SINCE BOUNDARY WILL PUSH
THROUGH WITH PRESENCE OF MOISTURE. JET POSITIONING ALSO FAVORS AT
LEAST SLIGHT CHANCES WITH NORTHWESTERN NEVADA UNDER THE RIGHT
ENTRANCE REGION.

GUSTY NORTHERLY WINDS BEHIND THE SURFACE BOUNDARY WILL PUNCH COOLER
TEMPERATURES INTO THE REGION SUNDAY NIGHT INTO MONDAY RESULTING IN
HIGHS NEARLY 10 DEGREES BELOW SEASONAL AVERAGES. RIDGING BUILDS AND
PERSISTS OVER THE WESTERN U.S. THROUGH MID WEEK. A SLOW WARMING
TREND WILL BEGIN TUESDAY AS WINDS BECOME SOUTHWESTERLY. BOYD

AVIATION...

GUSTY WINDS AND, SUBSEQUENTLY, MECHANICAL TURBULENCE CONTINUE TO BE
THE PRIMARY IMPACTS THROUGH THE FORECAST PERIOD FOR MOST TERMINALS.
THE PRESSURE GRADIENT CONTINUES TO INCREASE OVERNIGHT AS LOW
PRESSURE MOVES ACROSS THE REGION. THE ORIENTATION OF THIS GRADIENT
IS GENERALLY NORTH TO SOUTH SUGGESTING STRONG FLOW FOR THE LEE SIDE
OF THE SIERRA. ALSO, WIND SPEEDS ACROSS THE PEAKS WILL CONTINUE TO
BE SOUTHWESTERLY AND INCREASE TO AROUND 70 KNOTS OVERNIGHT. THIS
WILL  CREATE FAVORABLE CONDITIONS FOR AN EXTENDED DURATION OF GUSTY
WINDS AND WIND SHEAR CONDITIONS FOR TERMINALS FROM THE TAHOE BASIN
NORTH. ALSO, MAINLY RAIN SHOWERS WITH MVFR RESTRICTIONS WILL BE
POSSIBLE FOR TERMINALS NEAR THE SIERRA CREST INCLUDING KTRK AND KTVL
FROM 12-18Z.

ANTICIPATE A BRIEF PERIOD WHERE WINDS SLOW AROUND LOCAL MIDNIGHT.
THIS WILL PRESENT AN ISSUE WITH LOW LEVEL WIND SHEAR AS PEAK LEVEL
WINDS CONTINUE TO INCREASE OVERNIGHT FROM THE SOUTHWEST. WITH THE
TIGHTENING PRESSURE GRADIENT AND INHIBITION OF THE STABILIZING
EFFECTS OF NOCTURNAL RADIATION, WIND SPEEDS WILL RAMP BACK UP BY
09Z. TERMINALS CAN EXPECT WINDS GENERALLY FROM THE SOUTH AROUND 25
KNOTS WITH GUSTS TO 35 KNOTS. FOR TERMINALS ALONG THE SIERRA FRONT,
ESPECIALLY FOR THE RENO/CARSON AREA, SUSTAINED WINDS WILL LIKELY
BE HIGHER 30 TO 35 KNOTS WITH HIGHEST GUSTS IN EXCESS OF 40
KNOTS. LOCAL GUSTS COULD BE INTERMITTENTLY HIGHER AROUND 45 KNOTS.

KMMH WILL BE THE LEAST INFLUENCED LOCATION SINCE THE BOUNDARY
SIGNIFICANTLY WEAKENS BY THE TIME IT SAGS THIS FAR SOUTH. STILL
GUSTY CONDITIONS WILL BE PRESENT OVERNIGHT INTO WEDNESDAY. BOYD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...HIGH WIND WARNING UNTIL 10 AM PST WEDNESDAY NVZ005.

     WIND ADVISORY UNTIL 10 AM PST WEDNESDAY NVZ002.

     WIND ADVISORY UNTIL 10 AM PST WEDNESDAY NVZ003.

     LAKE WIND ADVISORY FROM 6 AM TO 4 PM PST WEDNESDAY FOR PYRAMID
     LAKE IN NVZ004.

CA...HIGH WIND WARNING UNTIL 10 AM PST WEDNESDAY CAZ070-071.

     WIND ADVISORY UNTIL 10 AM PST WEDNESDAY CAZ072.

&&

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