FXUS65 KREV 281851
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
1051 AM PST SAT NOV 28 2009

.UPDATE...
SNOW SHOWERS HAVE TAPERED TO MAINLY JUST SCATTERED SHOWERS OVER THE
HIGHER TERRAIN FROM ALPINE COUNTY SOUTH ALONG THE SIERRA CREST
THIS MORNING WITH A FEW SHOWERS IN THE HIGHER TERRAIN OF WESTERN
MINERAL AND SOUTHERN LYON COUNTIES. HAVE ALLOWED ALL WINTER
ADVISORIES TO EXPIRE BUT THINK A FEW SPOTS MAY PICK UP AN
ADDITIONAL INCH AT THE MOST IN THE HIGHER ELEVATIONS THROUGH THE
REST OF THE DAY. HAVE ALSO REDUCED SKY COVER NRN CWA AS DRIER AIR
WORKS SOUTH INTO THE AREA. WINDS AT LAKE TAHOE HAVE NOT PICKED UP
QUITE AS FAST AS ORIGINALLY FORECAST BUT THINK THIS WILL INCREASE
THROUGH THE AFTERNOON SO HAVE ADJUSTED THE TIMING. STILL
ANTICIPATING STRONG ENOUGH WINDS FOR A LAKE WIND ADVISORY. ON
PYRAMID THE WINDS WILL LIKELY INCREASE A BIT MORE THAN ORIGINALLY
FORECAST AND WAVES ON THE WEST SHORE WILL INCREASE. WILL HOLD THE
WINDS JUST BELOW LAKE WIND ADVISORY CRITERIA AS STRONGEST WINDS
SHOULD BE LATE THIS AFTERNOON AND ONLY LAST FOR 2 TO 3 HOURS. MLF

&&

.PREVIOUS DISCUSSION... /ISSUED 356 AM PST SAT NOV 28 2009/ 

SHORT TERM...A LOW PRESSURE SYSTEM CONTINUES TO TREK SOUTHEASTWARD
ALONG THE CALIFORNIA NEVADA BORDER THIS MORNING. LIGHT TO MODERATE
WRAP AROUND/DEFORMATION PRECIP BAND REMAINS INTACT FROM AROUND
HIGHWAY 50 SOUTH. THIS FEATURE SHOULD HOLD TOGETHER THROUGH THE
MORNING HOURS BEFORE DISSIPATING WITH DAYTIME HEATING AND WITH THE
LOW FINALLY EJECTING EAST. ON THE BACK SIDE OF THE LOW A STRONG
UPPER JET IS EXPECTED TO STRENGTHEN THIS AFTERNOON AND LEAD TO
GUSTY EASTERLY WINDS...ESPECIALLY OVER THE RIDGES OF THE SIERRA.
WINDS AT 700 MB FROM BOTH THE GFS AND NAM SUPPORT SUSTAINED WINDS
OF OVER 50 MPH WITH GUSTS OVER 75 MPH. AT THE SURFACE...GRADIENT
DRIVEN NORTHEAST WINDS WILL PERSIST MOST OF THE DAY AND HAVE
ISSUED A LAKE WIND ADVISORY FOR LAKE TAHOE. PYRAMID LAKE WILL SEE
GUSTS APPROACH 30 MPH...BUT DOESN'T LOOK TO BE STRONG ENOUGH TO
WARRANT AN ADVISORY. THE WINDS WILL SUBSIDE LATE SATURDAY NIGHT AS
A RIDGING PATTERN BEGINS TO BUILD INTO THE REGION. THIS WILL LEAD
TO STRONG VALLEY INVERSIONS SUNDAY AND MONDAY MORNINGS WITH THE
POTENTIAL FOR PATCHY FOG IN SIERRA VALLEYS.  LABELLE/MILNE

LONG TERM...TUESDAY THROUGH FRIDAY...
FEW CHANGES WERE MADE AGAIN THIS MORNING AS MODELS CONT TO HAVE 
DIFFICULTY WITH LONGWAVE PATTERN OVR THE ERN PAC/NORTH AMERICA AS 
STRONGER AND MORE PROGRESSIVE FLOW DEVELOPS UPSTREAM OVER THE 
CNTRL/WRN PAC. AT BEGINNING OF PD TROF OVR GULF OF ALASKA SPLITS AND 
SRN EXTENSION CLOSES OFF AND DIVES SEWD TWD CA. THE ECMWF IS THE NRN 
MOST MEMBER WITH THIS FEATURE AND WOULD BRING SOME CHANCE OF LIGHT 
PCPN TO THE SIERRA AS WELL AS SLIGHTLY STRONGER WIND FLOW. WHILE THE 
ECMWF IS PREFERRED EARLY ON IN THE LONGWAVE PATTERN...A COMPROMISE 
TRACK WAS TAKEN BETWEEN THE ECMWF AND GFS WHICH WOULD KEEP THE AREA 
DRY. S/W RDG BUILDS INTO AREA BEHIND WK SYSTEM WITH SEASONAL TEMPS 
FOR MID WEEK. BEYOND MID WEEK...EACH MODEL MAKES ITS OWN STATEMENT 
RANGING FROM COLD UPR LOW DROPPING SWD RIGHT OVR NV IN THE GEM TO A 
WEAKER S/W IN THE ECMWF WHICH DROPS SEWD INTO ERN NV-UT. THE OP GFS 
WAS IN BETWEEN THESE TWO SOLNS. THE ONLY CHANGE THAT WAS MADE WAS TO 
SHOW A SLIGHT TREND DOWNWARD IN HIGH TEMPS THU-FRI AS WELL AS INTO 
THE PRELIMINARY GRID FOR SAT. OTHERWISE THE FCST WAS KEPT DRY. 
HOHMANN 

AVIATION...
UPSLOPE FLOW AND MOISTURE IN DEFORMATION ZONE WL KEEP WDSPRD 
MVFR-IFR CONDS ALONG ERN SIERRA RTES BETWEEN KRNO-KBIH THRU MUCH OF 
TODAY WITH IMPROVEMENT THIS EVENING AS UPR LOW MOVES SEWD AND PCPN 
BAND WEAKENS IN RESPONSE TO DRIER AIR ADVECTING IN BEHIND SYSTEM. 
AREA TAF SITES WL BE JUST NORTH OF LOWEST CIGS/VSBYS WITH A GENERAL 
DRYING/BREAKING OF CLOUDS TODAY. LOW CLOUDS AND MT OBSCUREMENT AT 
SIERRA TAF SITES SHOULD GRADUALLY RISE AND BREAK BY MIDDAY WITH VFR 
CONDS THIS AFTN THRU SUN. STG ELY FLOW OVR AREA RDGS TODAY AND TNGT 
WITH GUSTS TO 70KT. THERE MAY BE A PERIOD OF LLWS AT KTRK/KTVL 
OVRNGT AS THE SFC DECOUPLES UNDER CLEAR SKIES. HOHMAN &&

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR NVZ002.

CA...LAKE WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR CAZ072.

&&

$$

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