Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 202144
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
244 PM PDT SUN APR 20 2014

.SYNOPSIS...
WINDS INCREASE MONDAY WITH ONE MORE DAY OF MILD TEMPERATURES AHEAD
OF A STRONG COLD FRONT WITH 20 TO 25 DEGREES OF COOLING TUESDAY.
THERE ARE CHANCES FOR RAIN AND SNOW LATE MONDAY INTO TUESDAY WITH
LIGHT SNOW ACCUMULATIONS POSSIBLE IN THE HIGHER ELEVATIONS OF THE
SIERRA. A BREAK IS EXPECTED WEDNESDAY AND THURSDAY BEFORE A COLD,
WET SYSTEM ARRIVES HEADING INTO NEXT WEEKEND.


&&

.SHORT TERM...
FEW CHANGES MADE TO THE GOING FORECAST WITH MODELS ON TRACK WITH
THE STRONG COLD FRONT TUESDAY MORNING. NAM HAS COME IN WETTER WITH
THE OVERALL TREND IN THE MODELS SLIGHTLY FURTHER NORTH WITH THE
MOISTURE. STILL, EXPECT ONE MORE MILD DAY MONDAY AHEAD OF THE
FRONT AS WINDS INCREASE.

700 MB WINDS INCREASE TO AROUND 25 KTS BY 00Z MONDAY AFTERNOON
WITH A SUPPORTIVE SURFACE GRADIENT. EXPECT GUSTS TO 40-45 MPH NEAR
AND EAST OF THE SIERRA WITH A BIT LIGHTER WINDS FURTHER EAST. THE
WINDS INCREASE FURTHER AT 700 MB OVERNIGHT TO 40-45 KTS, BUT WE
LOSE THE DIURNAL COMPONENT FOR MIXING. STILL EXPECT TO SEE SOME
GUSTS 40-45 MPH NEAR AND AHEAD OF THE FRONT WITH SOME GUSTS TO 55
MPH IN THE WIND PRONE AREAS. THOUGHT ABOUT AN ADVISORY, BUT AT
THIS POINT, THE WINDOW FOR STRONGER GUSTS LOOKS TO BE SHORT FROM
MAYBE 02-06Z TUESDAY EVENING AND CONFIDENCE IS LOW. HOWEVER, WITH
THE EXPECTED WINDS, DID HOIST ADVISORIES FOR TAHOE AND PYRAMID
LAKES. ALSO ADDED BLOWING DUST OVERNIGHT NEAR AND EAST OF HIGHWAY
95, BUT CONFIDENCE IS NOT HIGH THERE ALTHOUGH I DO THINK THERE
WILL BE SOME JUST AHEAD OF THE FRONT AS WINDS SURFACE.

BEHIND THE FRONT, EXPECT SOME PRECIP IN THE SIERRA AND NORTHEAST
CA INTO EXTREME NW NV. WHILE MOISTURE IS SPARSE, THE FORCING IS
STRONG WHICH NORMALLY OVERCOMES THE LIMITED MOISTURE TO SOME
EXTENT. BEST CHANCES CENTERED AROUND 12Z, BUT AMOUNTS WILL ONLY BE
A TENTH TO 1/3 INCH IN THE FAVORED AREAS WITH A FEW HUNDREDTHS AT
BEST EVERYWHERE ELSE. SNOW LEVELS TO START NEAR 7500 FEET THEN
QUICKLY FALL TO AROUND 5000 FEET. SNOW ACCUMULATION APPEARS TO BE
LIMITED ABOVE 7000 FEET, AND THERE MAY BE SOME BRIEF ACCUMULATION
OVER THE SIERRA PASSES FROM CARSON PASS NORTHWARD.

OTHER CONCERN BEHIND THE FRONT WILL BE THE GRADIENT WINDS AS A SFC
LOW SPINS UP OVER UTAH AND THE SFC GRADIENT TIGHTENS ALONG WITH
MUCH COLDER TEMPERATURES. WITH STRONG COLD AIR ADVECTION, EXPECT
WINDY CONDITIONS ALL AREAS WITH SUSTAINED WINDS AROUND 25 MPH AND
GUSTS 40-45 MPH. BLOWING DUST TO BE A BIT MORE OF A CONCERN WITH
THE WINDS SO ADDED IT TO TUESDAY AS WELL. WIND CHILLS WILL LIKELY
BE IN THE 30S ALL DAY, SO IT WILL FEEL LIKE WINTER HAS RETURNED.

INSTABILITY WILL ALSO INCREASE NORTH OF I-80 WITH THE COLD POOL
ALOFT. THEREFORE, EXPECT SCT SHOWERS TUESDAY AFTERNOON WITH SOME
POTENTIAL FOR THUNDER UNDER THE COLD POOL ITSELF. THESE
SHOWERS/STORMS COULD BRIEFLY LOWER SNOW LEVELS TO THE VALLEY
FLOORS. EXPECT THE SHOWERS AND STORMS TO WIND DOWN TUESDAY EVENING
ALONG WITH THE WINDS. WEDNESDAY LOOKS TO BE A TRANSITION AS THE
JET STREAM MOVES NORTH INTO WASHINGTON AND WEAK RIDGING OVER THE
SIERRA. TEMPERATURES WILL MODERATE SOME WITH DRIER WEATHER
ALTHOUGH A FEW SHOWERS WILL REMAIN POSSIBLE NEAR THE OREGON BORDER
CLOSER TO THE JET. WALLMANN

.LONG TERM...THURSDAY THROUGH SUNDAY...
AN UNSETTLED WEATHER PATTERN IS EXPECTED TO CONTINUE LATER THIS
WEEK THROUGH NEXT WEEKEND. THE LATEST GUIDANCE TRENDS FAVOR A
BETTER CHANCE OF PRECIPITATION FRIDAY AND FRIDAY NIGHT, WITH MORE
UNCERTAINTY IN RAIN AND SNOW CHANCES NEXT WEEKEND. AFTER A BRIEF
WARMUP ON THURSDAY, TEMPERATURES ARE MORE LIKELY TO DROP FRIDAY
AND REMAIN BELOW NORMAL THROUGH NEXT SUNDAY. OVERALL FORECAST
CONFIDENCE LEVELS ARE MEDIUM FOR THURSDAY-FRIDAY, THEN DROP TO LOW
FOR NEXT WEEKEND.

ON THURSDAY, FLAT RIDGE MOVES EAST ACROSS THE GREAT BASIN WITH NEXT
STORM SYSTEM APPROACHING THE WEST COAST. WIDESPREAD MID AND HIGH
LEVEL CLOUDS ARE EXPECTED ESPECIALLY NORTH OF HIGHWAY 50, WITH A FEW
SHOWERS POSSIBLE NORTH OF SUSANVILLE AND GERLACH. BASED ON THE MOST
LIKELY TIMING OF THE INCOMING SERIES OF WEATHER SYSTEMS, THURSDAY
SHOULD BE THE WARMEST DAY IN THE EXTENDED PERIOD WITH HIGHS NEAR 70
FOR LOWER ELEVATIONS AND MID TO UPPER 50S FOR THE SIERRA VALLEYS.

FOR FRIDAY AND FRIDAY NIGHT, THE 12Z GFS/ECMWF AND SOLID MAJORITY OF
THE ENSEMBLE DATA BRING THE NEXT TROUGH THROUGH THE SIERRA AND
WESTERN NEVADA. ALTHOUGH THIS SYSTEM IS PROJECTED TO SPLIT AS IT
MOVES INLAND, THE SOUTHERN PORTION OF THIS SPLIT IS LOOKING
HEALTHIER AS IT INCLUDES A BAND OF PACIFIC MOISTURE AND BETTER
FORCING ACROSS MOST OF THE SIERRA AS IT PASSES THROUGH THE REGION.
MOST OF THE GUIDANCE PRODUCES QPF VALUES OF 0.50 INCH TO 1 INCH NEAR
THE SIERRA CREST. FOR LOWER ELEVATIONS OF WESTERN NV, LIGHTER PRECIP
AMOUNTS MAINLY NEAR 0.10 INCH WITH LOCALLY UP TO 0.25 INCH ARE
POSSIBLE. THESE AMOUNTS ARE NOT VERY IMPRESSIVE, BUT COMPARED TO
MODEL DATA FROM YESTERDAY THIS IS A NOTABLE IMPROVEMENT IN PRECIP
POTENTIAL. DUE TO THIS INCREASED CHANCE OF RAIN AND SNOW,
TEMPERATURES WILL DROP SEVERAL DEGREES FROM THURSDAY, WHILE WINDS
ALSO INCREASE AS THE TROUGH AND SURFACE COLD FRONT PASS THROUGH THE
REGION. SOME UNCERTAINTY STILL EXISTS WITH SNOW LEVELS, BUT THE BEST
ESTIMATE IS BETWEEN 5500-6500 FEET FRIDAY AFTERNOON AND EVENING
ALONG THE SIERRA AND IN FAR WESTERN NV, THEN POTENTIALLY BOTTOMING
OUT NEAR 5000 FEET EARLY SATURDAY MORNING.

WHILE THE 12Z GUIDANCE TRENDS YIELD MORE RAIN AND SNOW TO THE REGION
ON FRIDAY, IT TAKES BACK SOME OF THE PRECIP POTENTIAL FOR NEXT
WEEKEND. THE GFS/ECMWF SHOW A BRIEF BREAK IN STORM SYSTEMS ON
SATURDAY, THEN ATTEMPT TO REBUILD A FLAT RIDGE OVER CA-NV BY SUNDAY
WITH THE STORM TRACK SHIFTING SLOWLY NORTHWARD TOWARD THE PACIFIC
NORTHWEST. OVERALL, THE SPREAD AMONG THE GUIDANCE IS HIGHER FROM
SATURDAY ONWARD SO WE WILL NOT MAKE ANY SIGNIFICANT CHANGES FROM THE
CURRENT FORECAST. WILL KEEP CHANCE POPS NEAR THE SIERRA AND NORTH OF
SUSANVILLE-GERLACH FOR MUCH OF NEXT WEEKEND, WITH SLIGHT CHANCE
ELSEWHERE ALONG WITH SHOWER WORDING TO INDICATE THE LOWER CONFIDENCE
IN RECEIVING A WIDESPREAD PRECIP EVENT. SATURDAY IS NOW MORE LIKELY
TO BE THE COOLEST DAY IN THE EXTENDED PERIOD WITH HIGHS STRUGGLING
TO REACH 60 DEGREES IN LOWER ELEVATIONS, AND ONLY 40S FOR THE SIERRA
VALLEYS. SUNDAY LOOKS TO BE NOT QUITE AS COOL BUT STILL BELOW NORMAL
FOR LATE APRIL. MJD

&&

.AVIATION...

LIGHT WINDS AND VFR CONDITIONS THROUGH MONDAY MORNING WITH
INCREASING COVERAGE OF MID AND HIGH CLOUDS DURING THE DAY MONDAY.
WINDS WILL INCREASE SHARPLY BY LATE MORNING NEAR THE SIERRA AND
EARLY AFTERNOON IN WESTERN NEVADA WITH FREQUENT GUSTS 35-40 KT AND
LEE SIDE MOUNTAIN WAVE TURBULENCE. THESE GUSTY WINDS ARE LIKELY TO
CONTINUE THROUGH TUESDAY.

RAIN AND SNOW SHOWERS COULD PRODUCE MVFR AND LOCAL IFR CIGS/VSBY
MAINLY NEAR THE SIERRA TERMINALS MONDAY NIGHT AND TUESDAY. FOR WEST
CENTRAL NV, SOME VSBY REDUCTIONS ARE ALSO POSSIBLE DUE TO BLOWING
DUST FROM LATE MONDAY AFTERNOON THRU TUESDAY. MJD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY FROM 1 PM TO 8 PM PDT MONDAY FOR PYRAMID LAKE
     IN NVZ004.

     LAKE WIND ADVISORY FROM 11 AM MONDAY TO 5 PM PDT TUESDAY FOR
     LAKE TAHOE IN NVZ002.

CA...LAKE WIND ADVISORY FROM 11 AM MONDAY TO 5 PM PDT TUESDAY 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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