Snow Advisory 5, NWS Reno, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
215 PM PST SAT DEC 17 2005

.SHORT TERM...
NEAR TERM...(TONIGHT)
HAVE RAISED POPS REST OF TODAY AND OVERNIGHT.  GOOD SURGE OF
MOISTURE MOVING RAPIDLY ACROSS THE CENTRAL VALLEY THIS AFTERNOON.
THIS SHOULD HIT THE SIERRA BY EARLY EVENING.  THEN MAIN SURE OF
MOISTURE SUNDAY THROUGH THE DAY.  NEW RUC ALSO GENERATING
PRECIPITATION THROUGH THE EVENING HOURS.  FISCHER

SUN THROUGH TUES...OVERNIGHT SYSTEM WILL PRIME THE ATMOSPHERE FOR
THE WETTER SYSTEM FOR SUN/SUN EVENING. DECENT WARM AIR ADVECTION
WITH SOME JET SUPPORT AND VERY MOIST ATMOSPHERE WILL RESULT IN A
DECENT SNOW EVENT FOR THE SIERRA. MODELS SHOW 1-2 INCH QPF FOR THE
SIERRA...BUT ON HMT CALL HPC SUGGESTED ANALOGS THAT SHOW 2-3 INCH
AMOUNTS WITH LOCALLY 4. AT THIS POINT...WILL GO WITH THE MIDDLE
RANGE OF THE ANALOG/MODEL WITH 1.5-2 INCHES ALONG THE CREST AND
AMOUNTS 20 MILES DOWNSTREAM UP TO AN INCH. HAVE ISSUED WARNING FOR
TAHOE/LASSEN AND ADVISORY FOR MONO WHERE THERE LOOKS TO BE MORE
SHADOWING. MONO MAY NEED TO BE UPGRADED LATER...BUT WILL GET THE
BALL ROLLING THIS WAY WITH SNOW STARTING ALREADY. FURTHER
NORTH...ACROSS NRN WASHOE/SURPRISE VALLEY...SNOW AMOUNTS MORE IN
QUESTION. DO NOT EXPECT AS MUCH SHADOWING THERE WITH VERY STABLE
PROFILE...AND SNOW LEVELS BE TAKE LONGER TO RISE. WILL KEEP THE
WATCH THERE FOR 3-6 INCHES AND LET LATER SHIFTS DECIDE. ALONG I-80
CORRIDOR OF WESTERN NV...EXPECT LIGHT SNOW CHANGING TO RAIN MAINLY
IN THE MORNING HOURS WITH MUCH MORE SHADOWING OVER MINERAL COUNTY.
COULD BE ISOLATED POCKETS OF FREEZING RAIN...BUT AT THIS TIME...PROG
SOUNDINGS SHOW A SNOW PROFILE. ALSO MAY NEED AN ADVISORY FOR
PERSHING COUNTY...BUT WILL AGAIN LEAVE TO LATER SHIFTS.

EVENT WILL GRADUALLY END LATE SUN EVENING...ALTHOUGH DO NOT EXPECT
MUCH CLEARING. RIDGE WILL AMPLIFY SOME INTO TUESDAY...BUT WITH THE
TROPICAL MOISTURE ENTRAINED IN THE FLOW IT WILL BE QUITE DIRTY. WILL
KEEP SKIES PARTLY TO MOSTLY CLOUDY THROUGH TUESDAY. GFS MORE
AGGRESSIVE WITH ANOTHER BAND OF PRECIP NW ZONES MONDAY WITH NAM
DRIER. WILL SPLIT THE ROAD AND KEEP CHC/SLIGHT CHC NW THIRD.

AS FAR AS TEMPS...WILL KEEP BELOW GUIDANCE WITH PRECIP SUNDAY...BUT
GO CLOSER TO GUIDANCE AND ABOVE NORMAL MON-TUE. MORE CLOUD COVER
WILL NOT BE FAVORABLE FOR A REPEAT OF LAST WEEKS INVERSION
CONDITIONS...BUT THIS IS LOWER CONFIDENCE THAN THE WEEKEND FORECAST.
WALLMANN

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
MEDIUM RANGE MODELS HAVE COME IN BETTER AGREEMENT THROUGH THE MIDDLE
OF NEXT WEEK WITH NEXT SYSTEM APPROACHING THE WEST COAST ON
WEDNESDAY THEN MOVING ACROSS THE AREA ON THURSDAY. THEREFORE MORE
WET WEATHER IN STORE FOR WEDNESDAY AND THURSDAY BEFORE SYSTEM PUSHES
EAST. MODELS IN SIMILAR AGREEMENT ON STRENGTH...WITH 570 DAM OR
HIGHER 500 MB HEIGHTS ACROSS THE RENO AREA THROUGH THE EVENT. 700 MB
TEMPERATURES DROP TO -3C AT THE COLDEST WHICH PUTS SNOW LEVELS ABOVE
7000 FEET...HOWEVER COOLER AIR TRAPPED IN VALLEYS WOULD TEND TO
LOWER THESE SNOW LEVELS TO NEAR 6000 FEET OR SO. WEAK RIDGE BUILDS
INTO THE AREA ON FRIDAY AND AMPLIFIES EARLY SATURDAY AS TROUGH OVER
THE PACIFIC APPROACHES THE COAST. MODELS STILL DISAGREE WITH THE
SYSTEM OVER THE HOLIDAY WEEKEND. THE EUROPEAN BRINGS A DEEPER TROUGH
TOWARD THE WEST COAST ON SATURDAY...MORE SIMILAR TO THE 00Z GFS RUN.
HOWEVER THE 12Z GFS RUN BRINGS A NEGATIVELY TILTED TROUGH FURTHER
NORTH INTO THE PAC NW COAST. THEREFORE AMOUNT OF PRECIP AND TIMING
STILL UNCERTAIN FOR THE HOLIDAY.  WILL CONTINUE TO CARRY SLIGHT
CHANCE POPS INTO THE MORNING OF THE 25TH FOR THE NRN SIERRA AND FAR
NWRN NV. TEMPERATURES SHOULD BE NEAR TO ABOVE NORMAL AS HEIGHTS RISE
AND THERE SHOULD NOT BE A SIGNIFICANT INVERSION SET UP TO KEEP THE
VALLEYS COOLER. BENINATO

&&

.AVIATION...
INCREASING MID LEVEL CLOUDS AHEAD OF APPROACHING STORM SYSTEM
THROUGH THE AFTERNOON AND EVENING. BASES WILL GRADUALLY LOWER AND
SNOW WILL BEGIN IN THE SIERRA BY THIS EVENING AND EVENTUALLY SPREAD
OVER WRN NV BY MORNING. IFR OR LIFR CONDITIONS EXPECTED WEST AND
NORTH OF RENO AT TAF SITES AND OVER TWEB ROUTES AS SNOW INCREASES.
VFR OR MVFR CONDITIONS EXPECTED SOUTH OF RENO. BENINATO

&&

.REV WATCHES/WARNINGS/ADVISORIES...
.NV...WINTER STORM WARNING NVZ002 6 AM TO 11 PM SUNDAY.
      WINTER STORM WATCH NVZ005 9 AM TO 9 PM SUNDAY.
.CA...WINTER STORM WARNING CAZ071-072 6 AM TO 11 PM SUNDAY.
      SNOW ADVISORY CAZ073 6 AM TO 11 PM SUNDAY.
      WINTER STORM WATCH CAZ070 9 AM TO 9 PM SUNDAY.
&&