Winter Storm Watch 2, NWS Reno, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
328 AM PST MON DEC 7 2015

.SYNOPSIS...

MAINLY DRY WEATHER AND ABOVE NORMAL TEMPERATURES ARE EXPECTED
THROUGH MIDWEEK. FOR WEDNESDAY NIGHT THROUGH THURSDAY, A POTENT
PACIFIC STORM WILL BRING STRONG WINDS AND POTENTIALLY HEAVY SIERRA
SNOW AND LOWER ELEVATION RAIN. COOLER AND SHOWERY CONDITIONS ARE
EXPECTED FRIDAY AND SATURDAY, WITH ANOTHER STRONG STORM POSSIBLE
BY SUNDAY.

&&

.SHORT TERM...

MAINLY QUIET WEATHER IS EXPECTED THROUGH MOST OF WEDNESDAY AS FLAT
RIDGE OF HIGH PRESSURE PUSHES THE MAIN MOISTURE FEED AND STORM
TRACK NORTHWARD INTO THE PACIFIC NORTHWEST. SOME LIGHT RAIN
SHOWERS REMAIN POSSIBLE NEAR THE OREGON BORDER THROUGH TONIGHT,
BUT SIGNIFICANT RAINFALL IS UNLIKELY. WIDESPREAD MID AND HIGH
LEVEL CLOUD COVER IS EXPECTED ACROSS MOST OF THE REGION,
ESPECIALLY NORTH OF HIGHWAY 50 THROUGH WEDNESDAY. RIDGE LEVEL
WINDS WILL REMAIN RELATIVELY GUSTY THROUGH TONIGHT AS 700 MB FLOW
GENERALLY RANGES FROM 25-35 KT, THEN AFTER A SHORT LULL ON TUESDAY
THE RIDGE WINDS WILL INCREASE FURTHER TUESDAY NIGHT AND
WEDNESDAY. FOR LOWER ELEVATIONS, FORECAST SOUNDINGS INDICATE
LIMITED MIXING ESPECIALLY THROUGH TUESDAY, RESULTING IN ONLY A
MODEST INCREASE IN WINDS. TEMPERATURES WILL REMAIN RATHER MILD
WITH HIGHS MAINLY IN THE 50S TO LOWER 60S FOR SIERRA VALLEYS AND
LOWER ELEVATIONS.

FOR WEDNESDAY, WE SHOULD BEGIN TO SEE WINDS INCREASE IN LOWER
ELEVATIONS. THE LATEST GUIDANCE IS TRENDING SLIGHTLY SLOWER WITH
THE ARRIVAL OF THE NEXT STORM, WHICH WOULD DELAY THE ONSET OF
STRONGER WINDS UNTIL WEDNESDAY NIGHT. FOR NOW WE WILL BRING A
MODERATE INCREASE IN WINDS DURING THE DAY WEDNESDAY WITH GUSTS
MAINLY 30-40 MPH, POSSIBLY A BIT HIGHER ACROSS FAR NORTHWEST NV
AND THE SURPRISE VALLEY.

THIS WILL CHANGE DRASTICALLY BY WEDNESDAY NIGHT AS THE SURFACE
PRESSURE GRADIENT BECOMES VERY TIGHT, WHILE THE 700 MB FLOW
INCREASES TO NEAR 70 KT AND 500 MB FLOW AROUND 100 KT. EVEN
WITHOUT MANY OF THE CLASSIC DOWNSLOPE SIGNATURES SHOWING UP ON
FORECAST SOUNDINGS, THE STRENGTH OF THE PRESSURE GRADIENT COULD
SUPPORT WIND GUSTS OF 60 MPH OR HIGHER IN LOWER ELEVATIONS BY
LATE WEDNESDAY NIGHT, WITH POSSIBLE GUSTS ABOVE 70 MPH IN WIND
PRONE AREAS. WIND GUSTS ON THE THE SIERRA RIDGES WILL EASILY
SURPASS 100 MPH PRIOR TO THE ONSET OF PRECIPITATION. RAIN AND HIGH
ELEVATION SNOW SHOULD BEGIN WEDNESDAY NIGHT IN NORTHEAST CA-FAR
NORTHWEST NV, BUT THE BULK OF THE MOISTURE IS MORE LIKELY TO HOLD
OFF UNTIL THURSDAY. MJD

.LONG TERM...THURSDAY THROUGH SUNDAY...

FORECAST CONFIDENCE REMAINS HIGH THAT WE WILL SEE ACTIVE WEATHER
THROUGH THE LATTER PART OF THE WEEK AND INTO NEXT WEEKEND AS THE
JET STREAM MOVES INTO NORTHERN CA/NV. A MODEST ATMOSPHERIC RIVER
WITH AROUND 1.25" PRECIPITABLE WATER WILL ALSO CONTRIBUTE TO THIS
STORM, BRINGING MODERATE TO HEAVY PRECIPITATION TO THE SIERRA AND
WESTERN NEVADA THURSDAY INTO THURSDAY NIGHT.

STRONG DOWNSLOPING WINDS WILL CONTINUE INTO EARLY THURSDAY MORNING
AS THE 165 KT JET PUSHES INTO THE SIERRA. WIND GUSTS UP TO 65 MPH
MAY BE POSSIBLE IN THE VALLEYS, WITH SIERRA RIDGES GUSTING OVER
100 MPH. AS THE MOISTURE PLUME ARRIVES INTO THE SIERRA EARLY
THURSDAY MORNING WINDS WILL BEGIN TO BACK OFF AS PRECIPITATION
TAKES OVER.

THE DEEP PLUME OF PACIFIC MOISTURE WILL COMBINE WITH A STRONG 700 MB
JET TO PRODUCE HEAVY PRECIPITATION RATES IN THE SIERRA THURSDAY.
WE COULD LIKELY SEE LIQUID AMOUNTS UP TO 4 INCHES ALONG THE SIERRA
CREST OVER 36 HOURS, MAKING THIS THE BIGGEST STORM WE'VE SEEN SO
FAR THIS SEASON. SNOW LEVELS WILL START OUT FAIRLY HIGH--AROUND
7000 FEET EARLY ON, THEN TRANSITION TO AROUND 5500 FEET BY
THURSDAY AFTERNOON BEHIND THE COLD FRONT.

SIGNIFICANT IMPACTS TO TRAVEL ARE EXPECTED IN THE SIERRA LATE
WEDNESDAY NIGHT THROUGH FRIDAY WITH THIS STORM. ANYONE WITH TRAVEL
PLANS DURING THIS TIME SHOULD STAY TUNED TO THE FORECAST. IT IS NOT
OUT OF THE QUESTION THAT WE COULD SEE SEVERAL FEET OF SNOW IN THE
SIERRA ABOVE 7000 FEET AND EVEN 6-12" AT LAKE TAHOE LEVEL. SNOWFALL
WILL START OUT AS HEAVY SIERRA CEMENT, THEN TRANSITION TO HIGHER
SNOW RATIOS LATE THURSDAY INTO FRIDAY BEHIND THE COLD FRONT. AS FOR
WESTERN NEVADA, SPILLOVER WILL BE EXCELLENT ON THURSDAY BEHIND THE
COLD FRONT WITH RAINFALL AMOUNTS OF OVER 0.50" POSSIBLE THURSDAY,
WITH SOME LOCATIONS SEEING UP TO AN INCH OF RAIN.

ANOTHER WINTER STORM WILL APPROACH THE REGION ON SUNDAY, BUT THERE
IS STILL SOME UNCERTAINTY IN THE AMOUNTS OF PRECIP AS THE MODELS
HAVE BEEN INCONSISTENT WITH THE TIMING AND PLACEMENT OF THE JET.
THIS STORM DOES LOOK COLDER THAN THE THURSDAY STORM, SO SNOW IMPACTS
MAY REACH INTO THE VALLEYS OF WESTERN NEVADA AS WELL SUNDAY INTO
MONDAY. HOON

&&

.AVIATION...

A FEW SHOWERS REMAIN NORTH OF SUSANVILLE AND GERLACH TODAY WITH
PERIODS OF MVFR/IFR POSSIBLE. OTHERWISE, VFR CONDITIONS ARE EXPECTED
TODAY WITH LIGHTER WINDS. WINTER STORM IS EXPECTED TO IMPACT THE
REGION BY WEDNESDAY NIGHT INTO FRIDAY, BRINGING HIGH WINDS,
TURBULENCE, MOUNTAIN SNOW AND VALLEY RAIN. HOON

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

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