High Wind and Strong Wind in Nevada, March 31, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
936 AM PDT SAT MAR 31 2012

.UPDATE...
AT 930 AM, THE COLD FRONT SHOWS UP CLEARLY ON SATELLITE AND RADAR
EXTENDS FROM REDDING SOUTH TO OAKLAND. IF THE FRONT CONTINUES AT
ITS CURRENT WESTWARD PACE OF 15-20 MPH, IT WILL REACH WESTERN
LASSEN COUNTY BY NOON, THE TAHOE BASIN BY 2 PM AND RENO-CARSON
AND MONO COUNTY AT 3-4 PM.

SNOW LEVELS ARE AT 7000-7500 FEET IN THE TAHOE BASIN AND
6000-6500 FEET IN PLUMAS AND LASSEN COUNTIES. SNOW LEVELS MAY RISE
ANOTHER 500 FEET THIS MORNING, THEN LOWER BELOW 6000 FEET AS THE
FRONT MOVES INTO THE REGION. PROFILER AT BODEGA BAY CALIFORNIA
REPORTED A SNOW LEVEL OF 7000 FEET AHEAD OF THE FRONT DROPPING TO
4000 FEET BEHIND THE FRONT.

A FEW SHOWERS AHEAD OF THE FRONT ARE DIMINISHING AND SKIES ARE
CLEARING DOWNWIND OF THE SIERRA, OUTSIDE OF THE RENO-CARSON AREA.
THIS WILL ALLOW FOR INCREASED MIXING AND STRONGER GUSTS TO REACH
THE LOWER ELEVATIONS. A FEW RECENT GUSTS HAVE JUMPED TO 50-60 MPH
EAST OF THE CREST AND ALONG US-395, WITH RIDGE LEVEL GUSTS OF
UP TO 90 MPH.

BLOWING DUST AND VISIBILITY DOWN TO NEAR ZERO MAY BECOME AN ISSUE
ACROSS WEST CENTRAL NEVADA AS A LENGTHY DURATION OF 25-35 MPH
SUSTAINED WINDS PICK UP DUST FROM THE DRY LAKE BEDS.  BRONG

&&

.PREVIOUS DISCUSSION... /ISSUED 401 AM PDT SAT MAR 31 2012/

SHORT TERM...
ALL WIND AND WINTER HEADLINES WILL REMAIN IN PLACE TODAY AS
VIGOROUS UPPER LOW OFF THE CA COAST CONTINUES ITS EASTWARD TREK.
CURRENTLY WIND GUSTS HAVE ONLY INCREASED TO THE 30-40 MPH RANGE
BUT THAT WILL CHANGE ABRUPTLY IN THE NEXT FEW HOURS AS 700 MB FLOW
INCREASES TO 50-60 KT AND SFC PRESSURE GRADIENT BECOMES MUCH
TIGHTER BTWN 12-18Z. THIS TIGHT PRESSURE GRADIENT WILL KEEP STRONG
WINDS GOING THIS AFTERNOON EVEN AS PRECIP INTENSIFIES OVER THE
SIERRA AND SPILLS INTO FAR WRN NV INCLUDING THE RENO-CARSON
VICINITY. THE THREAT OF BLOWING DUST WILL EXIST OVER ALL OF WRN
NV, MONO COUNTY AND EXTREME ERN LASSEN COUNTY THRU MIDDAY BUT THEN
SHIFT TO AREAS NEAR AND EAST OF HWY 95 AS RAIN MAKES ITS EASTWARD
PUSH INTO NV.

FOR PRECIPITATION AND SNOWFALL, THE MAIN FOCUS WILL BE ALONG THE
COLD FRONT AS IT MOVES QUICKLY INTO NERN CA BY MIDDAY THEN SWEEPS
ACROSS THE SIERRA AND FAR WRN NV THRU THIS AFTN. A SHORT BURST OF
VERY HEAVY SNOW AND RAIN IS EXPECTED WITH THIS FRONT PASSAGE,
COMBINING WITH STRONG WINDS TO PRODUCE WHITEOUT CONDITIONS IN
HIGHER ELEVATIONS OF THE SIERRA NEAR LAKE TAHOE. SNOWFALL RATES
UP TO 3 INCHES PER HOUR WILL BE POSSIBLE WITH THIS SNOW BURST.
FOR THE LAKE TAHOE BASIN, RAIN WILL CHANGE TO SNOW THIS AFTERNOON
ALTHOUGH SNOW MAY NOT BEGIN TO ACCUMULATE ON ROADS UNTIL AFTER 3
OR 4 PM WHEN THE MOST INTENSE SNOW OCCURS AND IS ABLE TO OVERCOME
THE MELTING POWER OF THE HIGHER SUN ANGLES THIS LATE IN THE
SEASON. FOR THE RENO-CARSON VICINITY, THIS SAME HEAVY PRECIP BAND
ASSOCIATED WITH THE FRONT WILL LIKELY PRODUCE BETWEEN 0.10 AND
0.30 INCH OF WIND DRIVEN RAINFALL DURING THE AFTERNOON. THE HIGH
TEMPS IN AREAS WEST OF HWY 95 WILL OCCUR BEFORE NOON TODAY, BEFORE
TEMPS BEGIN TO FALL AS THE RAIN MOVES IN.

AFTER THE MAIN COLD FRONT PASSAGE, THE AREA OF WIDESPREAD SNOW
AND RAIN WILL WIND DOWN EARLY THIS EVENING. HOWEVER, IF TSTMS
DEVELOP OVER THE FAVORED AREAS FROM REDDING TO CHICO AS THE COLD
POOL ALOFT MOVES THROUGH, THESE TSTMS COULD SPREAD A FEW CONVECTIVE
SNOW BANDS INTO PARTS OF THE ADVISORY AREA THIS EVENING.

SINCE THE DURATION OF THE MORE INTENSE SNOWFALL IS COMPRESSED
INTO A SMALLER TIME FRAME AND PREDOMINANTLY IN THE DAYTIME HOURS,
SNOW AMOUNTS IN THE HIGHER ELEVATIONS OF THE TAHOE BASIN AND NERN
CA WERE TRIMMED BACK A COUPLE OF INCHES. BELOW 7000 FEET IN THE
TAHOE BASIN, UP TO 6 INCHES OF HEAVY WET SNOW ARE STILL LIKELY ON
UNPAVED SURFACES, ALTHOUGH ACCUMULATIONS ON MAJOR ROADS ARE MORE
LIKELY TO BE LIMITED TO A SLUSHY INCH OR TWO. FARTHER SOUTH INTO
MONO COUNTY, AREAS NEAR THE SIERRA CREST ABOVE 8000 FT CAN EXPECT
4 TO 8 INCHES BUT AMOUNTS DROP TO FEWER THAN 3 INCHES ALONG
HIGHWAY 395.

LATER TONIGHT THRU SUN MORNING, A FEW SNOW SHOWERS WILL LINGER
MAINLY IN THE SIERRA BUT ADDITIONAL ACCUMULATIONS WILL BE MINIMAL.
DRIER AIR WITH BRISK NORTHWEST WINDS WILL PREVAIL ON SUNDAY WITH
MAX TEMPS ABOUT 10 DEGREES BELOW NORMAL, ONLY REACHING THE LOWER
50S IN THE WRN NV VALLEYS AND AROUND 40 IN THE TAHOE BASIN.

BY MONDAY, FLAT RIDGE RETURNS TO THE REGION WITH DRY CONDITIONS
AND TEMPS REBOUNDING TO NEAR SEASONAL NORMALS NEAR 60 IN WRN NV
AND AROUND 50 IN THE TAHOE BASIN. MJD

LONG TERM...TUESDAY THROUGH FRIDAY...
MADE ONLY MINOR CHANGES TO THE EXTENDED FORECAST THIS MORNING.
MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT EARLY IN THE FORECAST BUT
THEN BEGIN TO DIVERGE BY DAY 6. GEM REMAINS A BIT OF AN OUTLIER
EARLY AND WAS GENERALLY NOT USED IN THIS FORECAST.

SHORT WAVE RIDGE AXIS TO THE EAST AT THE START OF THE FORECAST
CONTINUES TO SHIFT EAST TUESDAY. MEANWHILE LONG WAVE TROF IN THE ERN
PACIFIC WITH LOW OFF THE COAST OF BC SHIFTS TO NEAR THE COAST BY
TUESDAY NIGHT/WEDNESDAY MORNING. GEM IS FASTER BRINGING PCPN INTO THE
REGION AND PUSHING COLD FRONT THROUGH THAN EITHER ECMWF OR GFS. MOST
GEFS ENSEMBLE MEMBERS FAVOR THE SLOWER SOLUTIONS. SO LOWERED POPS
FOR TUESDAY BUT BUMPED THEM UP FOR WEDNESDAY AND WEDNESDAY NIGHT
ACROSS THE REGION WITH THE BEST CHANCES OVER THE NORTH AND ALONG THE
SIERRA. ALSO BUMPED UP TEMPS JUST A LITTLE FOR TUESDAY. TEMPS
WEDNESDAY ARE A BIT MORE PROBLEMATIC AS ECMWF AND GFS ARE EVOLVING A
LITTLE DIFFERENTLY. GFS IS A LITTLE FASTER TO BRING TROF AXIS INTO
THE REGION WHILE ECMWF IS HOLDING COLDEST AIR JUST OFF SHORE. GFS
HAS A LITTLE MORE ENSEMBLE SUPPORT SO LOWERED TEMPS A LITTLE MORE
FOR BOTH WEDNESDAY AND THURSDAY. ONE THING I CONSIDERED FOR
WEDNESDAY BUT DID NOT ADD WAS TSTMS. H500 TEMPS DROP TO NEAR -30C BY
LATE WEDNESDAY WITH H400 TEMPS AROUND -40C. GIVEN IT IS EARLY APRIL
THERE COULD BE SOME DAYTIME HEATING AND THINK IT IS NOT OUT OF THE
QUESTION TO DEVELOP ENOUGH INSTABILITY FOR TSTMS OVER THE NRN AND
ERN PORTIONS OF THE CWA. BUT...AS STATED...DID NOT ADD THESE YET.
WOULD PREFER TO SEE MORE INFORMATION AND BETTER AGREEMENT ON TEMPS
ALOFT.

BY THURSDAY MODELS START TO DIVERGE WITH GFS BECOMING MORE
PROGRESSIVE AND MORE OF AN OUTLIER. ECMWF AND GEM KEEP MAIN TROF
JUST WEST. GEFS ENSEMBLE MEMBERS ARE SHOWING MORE SPREAD AS WELL.
THIS ONLY GETS WORSE BY FRIDAY AS ECMWF DROPS THE MAIN TROF OVER THE
REGION AND GEM AND GFS START TO DVLP A SHORT WAVE RIDGE. AND AGAIN
THE GEFS ENSEMBLE MEMBERS DISPLAY QUITE A LOT OF SPREAD. THEREFORE
OPTED TO MAKE VERY FEW CHANGES BEYOND DAY 5 AND KEEP SMALL POPS
ACROSS THE MUCH OF THE AREA THURSDAY AND THE NW 1/3 FRIDAY. MLF

AVIATION...
LOW TO MID LVL WINDS WILL BE THE BIGGEST AVIATION IMPACT EARLY
TODAY. A STRONG PRESSURE AND THERMAL GRADIENT WILL RESULT IN
INCREASING SOUTHERLY WINDS OVER THE ENTIRE AREA. SFC GUSTS UP TO
55KTS ARE POSSIBLE EAST OF THE SIERRA...WITH SLIGHTLY LOWER GUSTS IN
THE SIERRA VALLEYS. OVER THE SIERRA RIDGES WIND GUSTS COULD EXCEED
95KTS. THIS WILL RESULT IN FAIRLY WIDESPREAD TURBULENCE THROUGH THE
DAY. LIMITED DIRECTIONAL SHEAR THIS MORNING WILL INCREASE A BIT BY
LATE AFTERNOON...BUT THERE SHOULD BE SPEED SHEAR OFF THE SFC THROUGH
MUCH OF THE DAY.

LATER THIS MORNING PCPN WILL START TO MOVE INTO THE SIERRA THEN
SPREAD EAST INTO THE AFTERNOON AND EVENING. LATE THIS MORNING
CIGS/VSBYS SHOULD DROP TO MVFR THEN IFR IN THE SIERRA WITH RAIN
CHANGING TO SNOW AS SNOW LEVELS FALL THIS AFTERNOON. THIS SHOULD
RESULT IN A FEW INCHES OF ACCUMULATION ON THE RUNWAYS AT KTRK AND
KTVL LATE THIS AFTN THRU THIS EVE.

EAST OF THE SIERRA VFR CONDITIONS SHOULD CONTINUE FOR MOST OF THE
DAY WITH THE EXCEPTION OF PARTS OF THE BASIN AND RANGE IN WESTERN
NEVADA AND LOWER ELEVATIONS IN MONO COUNTY WHERE THE STRONG GUSTY
WINDS WILL PRODUCE BLOWING DUST. THE BLOWING DUST COULD REDUCE VSBYS
TO LESS THAN 3/4 MILE AT TIMES THIS AFTERNOON AND EARLY EVENING. FOR
KRNO PCPN WILL BE LIMITED TO A BRIEF PERIOD THIS AFTN OR EARLY EVE
ASSOCIATED WITH A COLD FRONT. CIGS/VSBYS COULD BRIEFLY DROP TO
MVFR AS RAIN SHOWERS CHANGE TO SNOW SHOWERS WITH NO SIGNIFICANT
ACCUMULATION. FOR KMMH THE POSSIBILITY OF SHOWERS WILL BE MAINLY
LATE THIS EVENING AND OVERNIGHT. A PERIOD OF IFR CONDITIONS IS
POSSIBLE AFTER 01/06 UTC WHEN SNOW SHOWERS COULD BE HEAVY ENOUGH
FOR SOME SLUSHY ACCUMULATION. MLF

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON NVZ005.

     HIGH WIND WARNING UNTIL 8 PM PDT THIS EVENING NVZ001.

     HIGH WIND WARNING UNTIL 2 PM PDT THIS AFTERNOON NVZ002.

     WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 5 AM PDT
     SUNDAY NVZ002.

     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON NVZ003.

     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON NVZ004.

CA...HIGH WIND WARNING UNTIL 2 PM PDT THIS AFTERNOON CAZ071.

     WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 5 AM PDT
     SUNDAY CAZ071.

     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON CAZ070.

     HIGH WIND WARNING UNTIL 8 PM PDT THIS EVENING CAZ073.

     HIGH WIND WARNING UNTIL 2 PM PDT THIS AFTERNOON CAZ072.

     WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 5 AM PDT
     SUNDAY CAZ072.

&&

HTTP://WEATHER.GOV/RENO