Winter Storm and Strong Wind in Nevada, March 23 to 26, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
228 PM PDT TUE MAR 22 2011

.SHORT TERM...
JET STREAK NOW COMING INTO THE BASE OF THE TROF IN THE ERN PAC
AT ABOUT 37N 132W. AS THIS JET STREAK APPROACHES THE CA COAST
LATER TONIGHT PCPN WILL BEGIN TO DEVELOP AND PUSH INTO THE SIERRA
WHERE SNOW LEVELS WILL BE LOW ENOUGH FOR ALL PCPN TO START AS SNOW.
UPPER DIFFLUENCE OVER NRN CA WILL HELP TO FOCUS BEST LIFT FROM
TAHOE NORTH TONIGHT INTO EARLY WEDNESDAY MORNING. SO HIGHEST QPF
SHOULD START ACROSS THE FAR NRN CWA AND WORK ITS WAY SOUTH AS JET
MOVES IN AND SHIFTS FOCUS TO THE TAHOE AREA AND SOUTH WEDNESDAY
MORNING. SNOW ACCUMULATIONS COULD BE BORDERLINE FOR WARNINGS
FROM TAHOE NORTH IN SOME OF THE VALLEYS...BUT RECENT STORMS HAVE LEFT
THE AREA WITH SIGNIFICANT SNOW ON THE GROUND AND FEW PLACES TO
MOVE ADDITIONAL SNOW. EVEN THOUGH THE HEAVIEST PCPN MAY FALL
DURING THE EARLY PART OF THE DAY WEDNESDAY...WE COULD SEE
ACCUMULATIONS OF UP TO A FOOT ALONG THE WEST SIDE OF TAHOE AND
HIGHER AMOUNTS ABOVE 7000 FEET AND WEST OF HIGHWAY 395 IN LASSEN
COUNTY. HAVE UPGRADED WATCHES TO WARNINGS FOR THE TAHOE AREA AND
LASSEN/PLUMAS COUNTIES TONIGHT THROUGH WEDNESDAY EVENING. FOR MONO
COUNTY WILL DELAY THE WARNING UNTIL WEDNESDAY MORNING...BUT THEN
WITH NO SIGNIFICANT BREAK IN THE PCPN WILL RUN IT THROUGH FRIDAY
MORNING.

TO THE EAST THERE APPEARS TO BE LIMITED CHANCE FOR SPILL OVER WITH
THE FIRST STORM AS MID LEVEL FLOW REMAINS SRLY. WINDS SHOULD
INCREASE THROUGH LATE TONIGHT AND WEDNESDAY...BUT THIS WILL BE
MAINLY GRADIENT WIND AS THIS DOES FIT A DOWN SLOPE PROFILE. DO NOT
FORESEE ANY WIND ADVISORIES AS WIND GUSTS SHOULD REMAIN 40 MPH OR
LESS. EVEN ON PYRAMID LAKE THE WIND GUSTS SHOULD REMAIN AT OR
BELOW 30 MPH TONIGHT AND EARLY WEDNESDAY. SOME PCPN LIKELY EAST OF
THE SIERRA BY LATE WEDNESDAY AS SHORT WAVE SWINGS TO THE EAST AND
INSTABILITY INCREASES. NOTED ON THE GFS THAT CAPE EAST OF THE
SIERRA APPROACHES 100 J/KG OR MORE BY WEDNESDAY AFTERNOON. SO A
QUICK BURST OF PCPN COULD LOWER SNOW LEVELS TO THE VALLEYS...BUT
WOULD NOT ANTICIPATE ANY SIGNIFICANT ACCUMULATIONS.

THE SECOND STORM SYSTEM MOVES INTO THE SIERRA THURSDAY AFTERNOON.
AS NOTED THERE IS A LIMITED PERIOD OF LITTLE TO NO ACCUMULATION
AHEAD OF THIS STORM...WITH THE MORE DEFINED BREAK FROM TAHOE NORTH.
A WATCH HAS BEEN ISSUED FOR TAHOE NORTH THURSDAY AFTERNOON INTO
FRIDAY MORNING...WHILE THE WARNING RUNS THROUGH THIS ENTIRE TIME
FOR MONO COUNTY. QPF FROM THE MODELS IS NOW HIGHER WITH THIS
SYSTEM WHILE PWAT PLUME REMAINS AROUND 0.75-0.90 INCHES COMING
INTO CALIFORNIA. MID LEVEL TEMPS START COLDER WITH THIS SYSTEM AND
SNOW LEVELS ARE LOWER...SO LIKELY TO BE A MORE EFFICIENT SNOW
PRODUCER. SNOW RATIOS LOOK TO BE HIGHER AND THE HIGHEST SNOW FALL
RATES WILL BE OVERNIGHT THURSDAY NIGHT SO THINK THIS SYSTEM WILL
PRODUCE EVEN MORE SNOW THAN THE FIRST. LIQUID PCPN COULD APPROACH
2 INCHES ALONG THE CREST WITH THIS SYSTEM. THIS STORM ALSO HAS A
BETTER SPILL OVER POTENTIAL AS THE JET LINES UP MORE WSW THAN SSW
BY EARLY FRIDAY MORNING. ACCUMULATING SNOWS LIKELY INTO WRN NV
VALLEYS WITH THIS STORM AND WE MAY NEED AT LEAST WINTER WEATHER
ADVISORIES FOR THE HIGHWAY 50 AREA NORTH FROM THURSDAY EVENING
INTO THE OVERNIGHT HOURS. FOR NOW WILL HOLD OFF ON THESE AND LET
SUBSEQUENT SHIFT REEVALUATE.

A BRIEF BREAK IS POSSIBLE LATE FRIDAY INTO FRIDAY EVENING BEFORE
A THIRD SYSTEM STARTS TO LINE UP LATE FRIDAY NIGHT. THIS SYSTEM
ALSO APPEARS QUITE WET. INCREASED THE POPS IN THE SIERRA WITH THIS
SYSTEM FOR FRIDAY NIGHT...BUT MOST OF THIS STORM WILL AFFECT THE
EXTENDED PORTION OF THE FORECAST. MLF

.LONG TERM...SATURDAY THROUGH TUESDAY...
EVEN AFTER ALL OF THE ACTIVITY COMING THROUGH THIS WEEK...ONE MORE
STORM SYSTEM IS STILL ON TRACK TO AFFECT THE REGION BY SATURDAY AND
SAT NIGHT. AT THIS TIME THIS SYSTEM IS SHOWING SIGNS OF SPLITTING AS
IT REACHES THE SIERRA...BUT DECENT BATCH OF MOISTURE SHOULD STILL
TAKE AIM AT THE REGION DURING THE DAY SATURDAY WITH SHOWERS
CONTINUING INTO THE EVENING. SNOW AMOUNTS IN THE SIERRA AND TAHOE
BASIN WILL PROBABLY BE LESS INTENSE COMPARED TO THE THURS-FRI
SYSTEM...MAYBE SEVERAL INCHES AT LAKE LEVEL AND UP TO 1 FOOT ABOVE
7000 FEET BUT WITH THIS PROLONGED BARRAGE OF SNOW EVENTS THE TRAVEL
IMPACTS WOULD BE MORE SIGNIFICANT COMPARED TO THIS STORM STANDING
ALONE. MANY AREAS IN THE TAHOE BASIN ARE RUNNING OUT OF SPACE TO
PILE UP THE PLOWED SNOW. FOR THE LOWER ELEVATIONS OF WRN NV-NERN
CA...MOST OF THE PRECIP WILL OCCUR DURING THE DAYTIME WITH RAIN AND
WET SNOW MIX BELOW 5000 FT...AND MOST ROADS LIKELY REMAINING WET UP
TO 6000 FT THRU SAT AFTN. SOME SLUSH PATCHES MAY FORM ON ROADS SAT
EVE ABOVE 5000 FT IN AREAS WHERE SNOW SHOWERS PERSIST THRU SUNSET
BUT OVERALL TRAVEL IMPACTS IN WRN NV DO NOT LOOK TO BE SIGNIFICANT.

BY SUNDAY...MOST AREAS SHOULD BE DRY AS FLAT SHORTWAVE RIDGE MOVES
INTO THE REGION BEHIND THE DEPARTING TROF. WIDESPREAD HIGH CLOUDS
WILL SPREAD ACROSS MOST AREAS WITH A FEW LINGERING SNOW SHOWERS IN
THE SIERRA BUT NO SIGNIFICANT ACCUMULATION IS EXPECTED. TEMPS WILL
REBOUND TO NEAR NORMAL WITH MID-UPR 50S IN MOST LOWER ELEVATIONS
WITH LIMITED MIXING AND CLOUD COVER PREVENTING FURTHER HEATING.

FOR NEXT MON-TUES...MEDIUM RANGE GUIDANCE REMAINS IN DISAGREEMENT
WITH TRACK OF NEXT STORM SYSTEM. THE GFS IS MOST PROGRESSIVE AND
COLDEST WITH TROF AND COLD FRONT SWINGING THRU NRN NV MON
NIGHT...PRODUCING A BAND OF SNOW NEAR AND NORTH OF I-80 EARLY TUES
MORNING. THE CANADIAN MODEL STORM TRACK IS SLOWER AND FARTHER
WEST...BRINGING MOST OF THE PRECIP TO THE REGION ON TUESDAY. THE
ECMWF CLOSES THE LOW OFF THE WEST COAST...KEEPING VIRTUALLY ALL
PRECIP WEST OF THE SIERRA. MOST OF THE GFS ENSEMBLE MEMBERS ALSO
KEEP THE REGION DRY NOT DUE TO THE ECMWF SCENARIO BUT BECAUSE THEY
TRACK THE TROF EVEN FARTHER NORTH THAN THE 12Z OPERATIONAL GFS. EVEN
THE WETTEST SCENARIOS ONLY GENERATE LIGHT PRECIP SO POPS HAVE BEEN
SCALED BACK WITH MOST AREAS LIMITED TO SLGT CHC EXCEPT LOW END
CHANCE POPS IN PORTIONS OF THE SIERRA FROM TAHOE NWD AND INTO
EXTREME NWRN NV. WIDESPREAD CLOUD COVER WILL CONTINUE TO LIMIT
HEATING WITH WINDS NOT LIKELY TO PROVIDE SUFFICIENT MIXING...SO HAVE
KEPT MAX TEMPS SLIGHTLY BELOW NORMAL BOTH MONDAY-TUESDAY. MJD
&&

.AVIATION...
CONDITIONS TO WORSEN IN THE SIERRA TONIGHT...ESPECIALLY AFT 06Z WITH
NEXT ROUND OF SNOW ARRIVING. CIGS AND VSBY MAY NOT INITIALLY DROP
BELOW ALL LANDING MINIMUMS BUT BY 10-11Z SNOW INTENSITY IS EXPECTED
TO INCREASE SUFFICIENTLY TO IFR/OCNL LIFR WITH CIGS/VSBY DROPPING
BELOW ALL LANDING MINS...CONTINUING INTO EARLY WED EVE. MOST OF THE
SNOW SHOULD END BY 03Z ALTHOUGH LOW CLOUDS AND SCT -SHSN WILL REMAIN
POSSIBLE THRU WED NIGHT.

FOR KRNO AND WRN NV...VFR CONDS TO PREVAIL THRU EARLY WED
MORNING...THEN MIX OF SNOW AND RAIN WILL BRING MVFR AND POSSIBLE
BRIEF IFR CONDS TO KRNO AS EARLY AS 12Z AND CONTINUING TO VARY BTWN
VFR-MVFR THRU MUCH OF THE DAY. PRECIP INTENSITY UNLIKELY TO PRODUCE
VSBY OR CIGS BLW THE LANDING MINS FOR THE MAJOR AIRCRAFT. RUNWAY
SURFACE SHOULD GENERALLY REMAIN WET EVEN EARLY WED MORNING AS MIN
TEMPS STAY ABOVE FREEZING. IF PRECIP EASES WED AFTN...SOME SE-S WIND
GUSTS COULD APPROACH 30 KT. MJD
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...WINTER STORM WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING
     NVZ002.

     WINTER STORM WARNING FROM 11 PM THIS EVENING TO 8 PM PDT
     WEDNESDAY NVZ002.

CA...WINTER STORM WARNING FROM 11 PM THIS EVENING TO 8 PM PDT
     WEDNESDAY CAZ071.

     WINTER STORM WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING
     CAZ071-072.

     WINTER STORM WARNING FROM 5 AM WEDNESDAY TO 11 AM PDT FRIDAY
     CAZ073.

     WINTER STORM WARNING FROM 11 PM THIS EVENING TO 8 PM PDT
     WEDNESDAY CAZ072.

&&

HTTP://WEATHER.GOV/RENO