Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 280523
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
923 PM PST THU NOV 27 2014

.UPDATE...
TEMPERATURES ARE FALLING A LITTLE SLOWER THAN ORIGINALLY FORECAST
THIS EVENING EVEN THOUGH CLOUDS ARE THINNING OVER THE SRN CWA.
THIS IS MOSTLY DUE TO THE WINDS HAVING NOT DECOUPLED COMPLETELY
YET. WILL UPDATE FOR THIS TREND...BUT OTHERWISE WILL NOT MAKE ANY
CHANGES TO THE GOING FORECAST FOR WINDS FRIDAY AS YET.

&&

.PREVIOUS DISCUSSION... /ISSUED 331 PM PST THU NOV 27 2014/

SYNOPSIS...

WELL ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS CONTINUE THROUGH
FRIDAY. LOW PRESSURE WILL APPROACH THE WEST COAST AND BRING GUSTY
WINDS FRIDAY FOLLOWED BY PERIODS OF WIND, RAIN AND SIERRA SNOW THIS
WEEKEND AND INTO EARLY NEXT WEEK.

SHORT TERM...

WELL ABOVE NORMAL TEMPERATURES HAVE CONTINUED AGAIN TODAY WITH
HIGHS HITTING THE LOW 70S IN WESTERN NEVADA. INCREASING WINDS
ALOFT (SLIDE MOUNTAIN AROUND 60 MPH) AND CLEARING SKIES HAVE
ALLOWED WESTERN NEVADA TO MIX OUT FULLY. THE HIGH TEMPERATURE AT
RENO-TAHOE AIRPORT HAS TOPPED OUT AT 73 DEGREES (AS OF 3 PM),
BREAKING THE PREVIOUS RECORD OF 70 DEGREES SET BACK IN 1946! THE
SOUTH LAKE TAHOE AIRPORT HAS AT LEAST TIED ITS DAILY RECORD WITH
63 DEGREES SET BACK IN 2011.

LOW PRESSURE WILL PUSH INTO THE WEST COAST TONIGHT INTO FRIDAY WITH
STRONG GUSTY WINDS AND INCREASING CHANCES OF RAIN/SNOW AS WE GO INTO
THE WEEKEND. MODEL CROSS SECTIONS ARE SHOWING POTENTIAL FOR
DOWNSLOPING WINDS FRIDAY WITH GUSTS UP TO 45 MPH ACROSS MUCH OF THE
SIERRA FRONT. WINDS COULD GUST UP TO 55 MPH IN WIND PRONE AREAS
ALONG US-395/580. LAKE WIND ADVISORIES HAVE BEEN ISSUED FOR LAKE
TAHOE AND PYRAMID LAKE FOR FRIDAY AS WELL DUE TO EXPECTED CHOPPY
CONDITIONS. IF WINDS TREND ANY STRONGER WE MAY NEED WIND ADVISORIES
FOR THE EASTERN SIERRA AND SIERRA FRONT FRIDAY AS WELL.

MODELS CONTINUE TO SHOW A THIN BUT SOLID 1" PWAT PLUME PUSHING INTO
THE SIERRA FRIDAY NIGHT INTO SATURDAY. THIS WILL BRING PERIODS OF
RAIN AND SNOW TO THE SIERRA SATURDAY THROUGH SUNDAY AS A PAIR OF
IMPULSES MOVE ACROSS NORTHERN CA/NV. IT LOOKS LIKE THE FIRST BATCH
OF PRECIP WILL MOVE THROUGH THE TAHOE BASIN AND NORTHERN SIERRA ON
SATURDAY MORNING, WITH A SECOND BATCH OF PRECIP MOVING THROUGH
SUNDAY. THE TIMING ON THESE IS ONLY AT A MEDIUM CONFIDENCE AT BEST,
BUT IT DOES LOOK LIKELY THAT WE COULD SEE LIGHT TO MODERATE
ACCUMULATIONS FOR THE SIERRA OVER THE WEEKEND. LATEST NAM AND ECMWF
CONTINUE TO SHOW A BULLSEYE OF PRECIP INTO THE TAHOE BASIN AND THE
NORTHERN SIERRA, SO WE`VE INCREASED QPF VALUES FOR THE WEEKEND. 48
HOUR TOTAL LIQUID PRECIPITATION VALUES (FRIDAY NIGHT THROUGH SUNDAY
NIGHT) IN THE SIERRA WILL TOTAL BETWEEN 0.5-1.0" WITH LESS THAN
0.25" IN WESTERN NEVADA DUE TO STRONG SHADOWING. BEST CHANCE FOR
SEEING SOME RAIN DOWN INTO WESTERN NEVADA WILL BE SUNDAY MORNING.

REGARDING SNOW LEVELS, MODELS ARE IN GOOD AGREEMENT WITH A DEEP
ISOTHERMAL LAYER ABOVE THE SIERRA THAT WILL ALLOW SNOW LEVELS TO
PUSH DOWN TO LAKE LEVEL BY SATURDAY MORNING IN THE HEAVIER PRECIP
(AIDED BY EVAPORATIVE COOLING AS WELL). SNOW WILL HEAVY AND WET,
WITH TEMPERATURES RIGHT AROUND FREEZING IN THE SIERRA. SNOW AMOUNTS
AT LAKE LEVEL WILL BE MINIMAL AROUND 2 TO 5 INCHES OVER THE WEEKEND
WITH 6 TO 12 INCHES POSSIBLE ALONG THE SIERRA CREST ABOVE 7000 FEET.
ANYONE TRAVELING OVER THE SIERRA PASSES THIS WEEKEND SHOULD BE
PREPARED FOR WINTER DRIVING CONDITIONS AND POSSIBLE DELAYS. SNOW
LEVELS SHOULD DROP TO AS LOW AS 5500 FEET AROUND RENO-TAHOE AND EVEN
AS LOW AS 4000 FEET NEAR THE OREGON BORDER AS MUCH COLDER AIR STARTS
TO FILTER IN FROM THE NORTH. PRECIP CHANCES REALLY CUT OFF SHARPLY
SOUTH OF ALPINE COUNTY, WITH ONLY A FEW INCHES POSSIBLE IN THE HIGH
SIERRA OF MONO COUNTY THIS WEEKEND. HOON

LONG TERM...MONDAY THROUGH THURSDAY...

THE START OF NEXT WEEK DOES NOT LOOK AS WET AS PREVIOUSLY EXPECTED.
A RIDGE AXIS BRIEFLY SETTING UP OVER WESTERN NV COULD KEEP MUCH OF
THE REGION RELATIVELY DRY MONDAY AND MONDAY NIGHT, ALTHOUGH A WEAK
SHORTWAVE MAY KEEP SOME LIGHT PRECIP GOING OVER NORTHEAST CA AND
NORTHWEST NV. SOME ENSEMBLE MEMBERS STILL KEEP MUCH OF THE REGION
WET FROM MONDAY THROUGH MONDAY NIGHT, BUT THE OVERALL TREND THAT
APPEARS TO BE DEVELOPING IS A 24-36 HOUR BREAK IN MOST PRECIP
ACTIVITY OVER EASTERN CA-WESTERN NV EARLY NEXT WEEK, ESPECIALLY IN
AREAS SOUTH AND EAST OF A GERLACH-RENO-SOUTH LAKE TAHOE LINE.

THE NEXT ROUND OF MOISTURE AHEAD OF THE MAIN LOW OFF THE CA COAST IS
NOW PROJECTED TO REACH THE SIERRA AND SPREAD ACROSS WESTERN NV BY
TUESDAY ON THE GFS, OR TUESDAY NIGHT ON THE ECMWF. PERIODS OF RAIN
AND SNOW ASSOCIATED WITH THIS LOW SHOULD CONTINUE INTO AT LEAST
WEDNESDAY AS THE LOW MOVES INLAND. CONFIDENCE IS MEDIUM FOR THE
POTENTIAL FOR RAIN AND SNOW OCCURRING IN THE SIERRA AND WESTERN
NEVADA FOR THE MIDDLE OF NEXT WEEK. HOWEVER, CONFIDENCE IS
SIGNIFICANTLY LOWER WITH SNOW LEVELS AND PRECIP AMOUNTS SINCE THE
TRAJECTORY OF THE MOISTURE FEED AND STORM TRACK VARIES AMONG THE
MEDIUM RANGE GUIDANCE. PRELIMINARY SNOW LEVELS GENERALLY RANGE FROM
6000-7000 FEET FROM TUESDAY THROUGH WEDNESDAY, BUT COULD FLUCTUATE
BY SEVERAL HUNDRED FEET IN EITHER DIRECTION DUE TO THESE STORM TRACK
UNCERTAINTIES. PROJECTED LIQUID PRECIP AMOUNTS COULD REACH 1 INCH
WITH LOCALLY HIGHER AMOUNTS ALONG THE SIERRA CREST AND INTO
NORTHEAST CA, WITH A WIDE RANGE FROM BELOW 0.10 INCH TO AROUND 0.50
INCH POSSIBLE ACROSS LOWER ELEVATIONS OF EASTERN CA AND WESTERN NV.

FOR THURSDAY, OVERALL PRECIPITATION POTENTIAL SHOULD DECREASE,
ALTHOUGH THE ECMWF KEEPS MOISTURE STREAM GOING INTO NORTHEAST CA
THROUGH THE END OF NEXT WEEK. THE CURRENT FORECAST WILL KEEP CHANCE
POPS IN PLACE FROM TAHOE NORTHWARD, WITH SLIGHT CHANCE ELSEWHERE.

TEMPERATURES NEXT WEEK ARE PROJECTED TO REMAIN NEAR OR SLIGHTLY
ABOVE NORMAL WITH HIGHS MAINLY IN THE UPPER 40S TO MID 50S FOR LOWER
ELEVATIONS. MJD

AVIATION...

VFR CONDITIONS EXPECTED THRU FRIDAY WITH AREAS OF HIGH CLOUDS
OVERHEAD. PRECIPITATION CHANCES INCREASE SATURDAY AND SUNDAY WITH
RAIN IN LOWER ELEVATIONS AND SNOW POSSIBLE AT TIMES FOR THE SIERRA
TERMINALS. STRONG RIDGE WINDS CONTINUE THRU FRIDAY AND SATURDAY WITH
GUSTS 60-80 KT. WIND GUSTS MAINLY IN THE 20-25 KT RANGE TODAY WILL
INCREASE TO 30-40 KT FRIDAY RESULTING IN AREAS OF LEE SIDE
TURBULENCE WITH SOME MOUNTAIN WAVE ACTIVITY. MJD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY FROM 10 AM TO 6 PM PST FRIDAY FOR PYRAMID
     LAKE IN NVZ004.

     LAKE WIND ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     LAKE TAHOE IN NVZ002.

CA...LAKE WIND ADVISORY FROM 10 AM FRIDAY TO 4 AM PST SATURDAY FOR
     LAKE TAHOE IN CAZ072.

&&

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)





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