Winter Storm and Heavy Snow in Nevada, February 24 to 25, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
246 PM PST THU FEB 24 2011

.SHORT TERM...
WINTER STORM APPEARS TO BE ON TRACK FOR TONIGHT INTO EARLY
SATURDAY MORNING. AHEAD OF THE STORM GUSTY WINDS WILL CONTINUE
INTO THE EVENING FOR AREAS EAST OF THE SIERRA AND SOUTH OF
INTERSTATE 80. LOCALLY STRONG GUSTS TO NEAR 65 MPH HAVE BEEN
REPORTED IN SOME OF THE WIND PRONE AREAS ALONG HIGHWAY 395 AND
HIGHWAY 95...AND THIS COULD CONTINUE. BUT OVERALL GUSTS WILL BE
BELOW ADVISORY CRITERIA AND DECREASING INTO THE LATE EVENING
HOURS.

UPPER TROF DROPPING SOUTH ALONG THE PAC NW COAST TODAY. MODELS
SHOW A WEAK CLOSED CIRCULATION DEVELOPING THEN OPENING UP BEFORE
REDEVELOPING BY LATE FRIDAY IN CENTRAL CALIFORNIA. 130 KT JET IS
PULLING AROUND THE TROF AS WELL AND WILL LEAD TO INCREASE
LIFT/INSTABILITY BY FRIDAY OVER THE RGN. MODEL SOUNDINGS SHOWING
INSTABILITY DEVELOPING EAST OF THE SIERRA FRIDAY MORNING JUST
AHEAD OF THE SFC COLD FRONT WITH AN EXTENDED PERIOD OF
FRONTOGENTIC FORCING THAT SHOULD LEAD TO SOME RATHER IMPRESSIVE
SNOW FALL RATES DURING THE MORNING HOURS. TIMING COULD BE
PROBLEMATIC IN THE VALLEYS OF WRN NV AS SNOW FALL MAY NOT
ACCUMULATE AS FAST IF HEAVIEST SNOW IS DELAYED AND TEMPS WARM A
BIT. LATEST 18Z GFS IS COMING IN WITH MUCH MORE QPF FOR THIS EVENT
AS WELL...SO AMOUNTS MAY NEED TO BE UPPED BEYOND THIS
FORECAST...BUT FOR NOW WILL STICK WITH LOW END TO MID RANGE
WARNING NUMBERS FOR THE RENO AREA AND ONLY ADVISORY CRITERIA EAST
INTO FALLON AND LOVELOCK. DID UP THE QPF AND SNOW AMOUNTS FOR
LASSEN COUNTY AND MONO COUNTY FOR THIS EVENT. LASSEN COUNTY AREA
SHOULD HAVE GOOD DYNAMICS THIS EVENING. WITH LATEST GFS RUNS
SLOWING THE PASSAGE OF THE UPPER TROF AND FORMING A CLOSED
CIRCULATION TO OUR WEST THAT WOULD SUPPORT A LONGER DWELL TIME IN
THE SRN PART OF THE CWA AND HIGHER AMOUNTS FOR MONO COUNTY FRIDAY
NIGHT.

THIS ALSO BRINGS UP ANOTHER ISSUE. WITH UPPER LOW DEVELOPING...A
DEFORMATION AXIS IS LIKELY TO FORM BY EARLY SATURDAY MORNING WHICH
WOULD HOLD SNOW BANDS OVER WRN NV. THIS IS PROBLEMATIC FOR TIMING
THE END OF THE WARNINGS/ADVISORIES FROM TAHOE SOUTH AND INTO WRN
NV. DEPENDING ON WHERE A BAND DEVELOPS...AMOUNTS COULD BE HIGHER
AND WARNINGS/ADVISORIES MAY NEED TO BE EXTENDED INTO THE DAYTIME
HOURS SATURDAY. WILL LET SUBSEQUENT SHIFTS TAKE A LOOK AT THIS AND
AMOUNTS WITH THE FIRST PUSH.

BEYOND THIS EVENT THERE SHOULD BE A PERIOD OF DRYING AS UPPER LOW
EJECTS SATURDAY NIGHT THROUGH SUNDAY NIGHT. TEMPS WILL BE QUITE
COLD BEHIND THIS SYSTEM WITH FRESH SNOW COVER AND CLEARING SKIES.
LOWS SUNDAY MORNING LIKELY TO BE WELL BELOW ZERO IN THE SIERRA
VALLEYS AND SINGLE DIGITS TO LOW TEENS IN WRN NV VALLEYS. SOME
WEAK WARM UP BY MONDAY AHEAD OF ANOTHER DEVELOPING SYSTEM THAT
WILL AFFECT THE AREA IN THE LONG TERM. MLF

.LONG TERM...MONDAY THROUGH THURSDAY...
RIDGE IS PROJECTED TO FLATTEN OVER THE WRN US BY EARLY NEXT WEEK
WITH MORE PACIFIC MOISTURE AND ENERGY APPROACHING THE REGION. WHILE
THE ECMWF AND GEM KEEPS ALL AREAS DRY MON-MON NGT...THE GFS AND SOME
OF ITS ENSEMBLE MEMBERS SPREAD LIGHT SNOW INTO PARTS OF NERN CA-FAR
NWRN NV AS SOON AS MON AFTN OR EVE. HAVE SPLIT THE DIFFERENCE AND
KEPT MONDAY DRY BUT ADDED SLGT CHC FROM TAHOE NWD MON NIGHT. ENOUGH
COLD AIR IS LIKELY TO REMAIN IN PLACE TO KEEP ANY PRECIP IN THE FORM
OF SNOW FOR MON NIGHT.

FOR TUES-THURS...RETURN TO WETTER WEATHER IS PROBABLY AS SOUTHERN
BRANCH OF PACIFIC JET STRENGTHENS AND CARRIES SUBTROPICAL MOISTURE
TOWARD THE REGION. AIR MASS LIKELY TO BE WARMER WITH POTENTIAL FOR
SNOW LEVELS RISING TO 6500 OR 7000 FEET BY WEDNESDAY BEFORE LOWERING
TO LAKE LEVEL WED NIGHT. THE ECMWF/GEM DIRECT THE JET ENERGY FARTHER
NORTH WHICH WOULD YIELD EVEN HIGHER SNOW LEVELS...BUT LESS PRECIP IN
THE SIERRA AND WRN NV. FOR LOWER ELEVATIONS OF WRN NV...MOST PRECIP
WITH THIS MIDWEEK SYSTEM IS LIKELY TO BE IN THE FORM OF RAIN. NO
MAJOR CHANGES WILL BE MADE TO THE FORECAST WHICH IS IN GENERAL
AGREEMENT WITH THE NAEFS METEOGRAM WHICH GIVES HIGHEST POTENTIAL FOR
PRECIP BTWN TUES NGT-WED NGT. WINDS WILL INCREASE ESPECIALLY IN
RIDGES FROM LATE TUES THRU THURS AS 700 MB FLOW COULD REACH 50 KT AT
TIMES. MJD
&&

.AVIATION...
STRONG STORM WILL PRODUCE SIGNIFICANT IMPACTS ON AIR TRAVEL TONIGHT
THRU FRI EVE. FOR KTVL AND KTRK...CONDS TO WORSEN AROUND 00Z WITH
CIGS/VSBY BELOW ALL LANDING MINIMUMS DUE TO SNOW AND BLOWING SNOW
THRU ALL OF TONIGHT AND FRIDAY UNTIL AT LEAST 00Z...POSSIBLY
LINGERING THRU 06Z FRI EVE.

FOR KRNO...GUSTY S-SW WINDS WILL BE THE PRIMARY IMPACT THRU 06Z WITH
SOME GUSTS ABOVE 35 KT AT TIMES...THEN VSBY/CIGS BECOMING LOWER AFT
06Z WITH -SN DEVELOPING. BAND OF MDT-HVY SNOW MOST LIKELY TO AFFECT
KRNO BTWN 12Z-18Z WITH POTENTIAL FOR VSBY DROPPING BLW 1/2 MILE AT
TIMES. BAND OF HEAVIER SNOW COULD PERSIST BEYOND 18Z BUT THERE
IS STILL SOME UNCERTAINTY IN WHETHER IT SETS UP OVER KRNO. OTHER
AIRPORTS IN FAR WRN NV NEAR KRNO WILL ALSO EXPERIENCE SIMILAR CONDS
THRU FRIDAY.

FROM LATE FRI EVE THRU SAT MORNING BTWN 06Z-18Z...FINAL WRAP AROUND
SNOW BAND MAY KEEP MVFR/OCNL IFR CONDS OVER AREA TERMINALS. MJD
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...WINTER STORM WARNING UNTIL 4 PM PST FRIDAY NVZ005.

     LAKE WIND ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR LAKE TAHOE
     IN NVZ002.

     WINTER STORM WARNING UNTIL 4 AM PST SATURDAY NVZ002.

     WINTER STORM WARNING FROM 10 PM THIS EVENING TO 10 PM PST FRIDAY
     NVZ003.

     WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST FRIDAY NVZ004.

CA...WINTER STORM WARNING UNTIL 10 PM PST FRIDAY CAZ071.

     WINTER STORM WARNING UNTIL 4 PM PST FRIDAY CAZ070.

     WINTER STORM WARNING FROM 10 PM THIS EVENING TO 4 AM PST
     SATURDAY CAZ073.

     LAKE WIND ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR LAKE TAHOE
     IN CAZ072.

     WINTER STORM WARNING UNTIL 4 AM PST SATURDAY CAZ072.

&&

HTTP://WEATHER.GOV/RENO