Winter Storm Watch 7, NWS Reno, NV

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WWUS45 KREV 072216
WSWREV

URGENT - WINTER WEATHER MESSAGE
National Weather Service Reno NV
216 PM PST Tue Dec 7 2021

CAZ070-071-NVZ005-100000-
/O.UPG.KREV.WS.A.0007.211209T0000Z-211210T0000Z/
/O.NEW.KREV.WW.Y.0020.211209T0000Z-211210T0000Z/
Surprise Valley California-Lassen-Eastern Plumas-
Eastern Sierra Counties-Northern Washoe County-
216 PM PST Tue Dec 7 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM WEDNESDAY TO 4 PM
PST THURSDAY ABOVE 5000 FEET...

* WHAT...Winter Weather Advisory for snow above 5000 feet. Total 
  snow accumulations of up to 4 inches, except 3 to 8 inches west 
  of highway 395. Accumulations of up to 1 inch will be possible 
  below 5000 feet.

* WHERE...Above 5000 feet for the following areas: Surprise 
  Valley California, Lassen- Eastern Plumas- Eastern Sierra 
  Counties and Northern Washoe County.

* WHEN...From 4 PM Wednesday to 4 PM PST Thursday.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS...Snow levels will start around 6000 feet
  late Wednesday afternoon and rapidly fall overnight into
  Thursday morning. Even slushy roadways at lower elevations can 
  create hazardous travel conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Even light snowfall causes major travel delays, especially during
periods of high traffic volume. Be sure to allow extra time to
reach your destination. Leave extra space between vehicles since
it takes longer to stop on slick roadways. 

The latest road conditions can be obtained by calling 5 1 1.

&&

$$

CAZ073-NVZ001-003-004-100000-
/O.UPG.KREV.WS.A.0007.211209T0600Z-211210T0600Z/
/O.NEW.KREV.WW.Y.0020.211209T0000Z-211210T0000Z/
Mono County-Mineral and Southern Lyon Counties-Greater Reno-
Carson City-Minden Area-
Western Nevada Basin and Range including Pyramid Lake-
Including the cities of Bridgeport, Coleville, Mammoth Lakes, 
Verdi, and Virginia City
216 PM PST Tue Dec 7 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM WEDNESDAY TO 4 PM
PST THURSDAY ABOVE 5000 FEET...

* WHAT...Winter Weather Advisory for snow above 5000 feet. Total
  snow accumulations of 2 to 7 inches, except 4 to 8 inches above
  7000 feet. Isolated higher elevations above 9000 feet may
  receive close to a foot. Accumulations of up to 1 inch will be
  possible below 5000 feet, including the Carson City/Reno areas.
  Ridge top winds will gust between 50-70 mph.

* WHERE...Above 5000 feet for the following areas: Greater Reno-
  Carson City- Minden Area, Mineral and Southern Lyon Counties, 
  Mono County and Western Nevada Basin and Range including Pyramid
  Lake.

* WHEN...From 4 PM Wednesday to 4 PM PST Thursday.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the morning or evening commute.

* ADDITIONAL DETAILS...Snow levels will start around 6000 feet
  late Wednesday afternoon and rapidly fall overnight into
  Thursday morning. Even slushy roadways at lower elevations can
  create hazardous travel conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Even light snowfall causes major travel delays, especially during
periods of high traffic volume. Be sure to allow extra time to
reach your destination. Leave extra space between vehicles since
it takes longer to stop on slick roadways. 

The latest road conditions can be obtained by calling 5 1 1.

&&

$$

CAZ072-NVZ002-100000-
/O.UPG.KREV.WS.A.0007.211209T0000Z-211210T0600Z/
/O.NEW.KREV.WW.Y.0020.211209T0000Z-211210T0000Z/
Greater Lake Tahoe Area-
Including the cities of South Lake Tahoe, Truckee, Stateline, 
and Incline Village
216 PM PST Tue Dec 7 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM WEDNESDAY TO 4 PM
PST THURSDAY ABOVE 5000 FEET...

* WHAT...Snow expected. Total snow accumulations of 4 to 6 
  inches, except 6 to 12 inches above 7000 feet. Winds gusting as 
  high as 50 mph.

* WHERE...Greater Lake Tahoe Area.

* WHEN...From 4 PM Wednesday to 4 PM PST Thursday.

* IMPACTS...Travel could be very difficult. The hazardous
  conditions could impact the morning or evening commute. Gusty
  winds could bring down tree branches. Waves will create
  hazardous boating conditions on local lakes. 

* ADDITIONAL DETAILS...Strong southwest winds will create 
  hazardous waves of 2 to 4 feet on Lake Tahoe.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Even light snowfall causes major travel delays, especially during
periods of high traffic volume. Be sure to allow extra time to
reach your destination. Leave extra space between vehicles since
it takes longer to stop on slick roadways. 

The latest road conditions can be obtained by calling 5 1 1.

&&

$$

http://www.weather.gov/reno

Area Forecast Discussion
National Weather Service Reno NV
303 PM PST Mon Dec 6 2021

.SYNOPSIS...

A fast moving weather system will bring light rain and high
elevation snow later today through tomorrow morning. A more potent storm
will bring an increased chance for snow Wednesday night into
Thursday, with some impacts likely down to lower elevations. Sharply
colder conditions continuing into next weekend. Next week could be
quite active with potentially significant winter weather conditions.

&&

.SHORT TERM (Through Wednesday)...

'tis the season that say farewell to our extended period of warmth and
clear skies as a noticeably more active weather pattern returns
to our neck of the woods. We will first touch on the weaker storm
which will move through this evening through the overnight hours.
A brief lull in the weather will transition to a potentially more
impactful weather system on Thursday, which will be covered more
in the long term discussion.

* Current afternoon radar and surface observation trends indicated a
  large swath of light rain/snow stretching from CA across central
  NV. Much of this is still virga except over higher elevations like
  Mt Rose highway. Nevertheless, as the lower levels continue to
  moisten through the afternoon hours, we expect this to finally
  make it to the ground. Confidence is high for measurable rainfall
  amounts south of US-50 where 12Z HREF guidance is on the order of
  80-100% for at least 0.01 inch of accumulation around the midnight
  hours. For the Reno-Carson areas, we have about a 40-60% of being
  able to finally measure something in the rain gauge. Higher-end
  HREF numbers suggest the highest amounts across Mono county, where
  12hr totals have a 40-60% of exceeding 0.50 inches of liquid. Part
  of this will fall as snow as we'll cover next...

* After the possibility of some light showers later this afternoon
  (and maybe a brief rain/snow shower or two at higher elevations
  above the drier layer), hi-res RAP & HRRR guidance shows an area
  of rapid cold air advection and moistening spreading southeast out
  ahead of an upper level trough. While there is high confidence in
  snow levels at least 7,500 feet and above, forecast soundings
  (South Lake Tahoe, for example) suggest a rather substantial wet-
  bulbing effect which may bring snow levels closer to 6,500 feet by
  9pm-12am. With that said, don't expect much accumulation even if
  we happen to make it near lake level. Snow totals through tomorrow
  look to be from a dusting to 1 inch around the Carson Range and
  Sierra within the I-80 corridor (between 6500-7500ft).
  Farther south, across Eastern El Dorado, Eastern Alpine, and Mono
  counties, look for 1-4 inches above 7500 feet. For Mono county
  above 8,500 feet, 3 to 6 inches of fresh snow will be possible.
  Expect some minor impacts across higher passes and perhaps even
  down to US395 in Mono county.

* Nothing too unusual with the winds for this system as the 700mb
  jet is not too impressive. Ridge-top winds on the order of 30-
  45mph with gusts up to 70 mph are possible. In the valleys, we'll
  remain 10-15 mph with occasional gusts up to 20 mph mainly this
  afternoon prior to the precip.

Rain/snow showers ongoing across Mono and Mineral counties will
dissipate from north to south during the morning hours on Tuesday.
After this precipitation exists our area, we will see a brief lull
in the weather. Highs will be cooler on Tuesday - but still a touch
above average for most areas. At least we can say goodbye to 60s!
Tuesday night will be chilly, with widespread 20s but it won't be
anything like the frigid temperatures we can look forward to by
late week... Brrr

-Dustin

.LONG TERM...Wednesday and Beyond...

Wednesday night into Thursday, a hybrid "inside slider" will move
through the region, which will drive a strong cold front across
eastern CA and NV and allow for snowfall down to all valley floors.
There is still high uncertainty in the timing and the strength of
this storm, but these sorts of systems are typically this way. Here
are the potential impacts:

-Winds:

* Breezy southwest to northwest winds are expected for most areas
  Wednesday-Thursday with localized travel and recreation impacts.
  There is a slight potential (~20%) for wind gusts up to 60 mph for
  the Eastern Sierra into Central NV, especially Wednesday
  afternoon. On Friday, cold north winds with low-end travel impacts
  are possible along the Eastern Sierra.

-Snowfall:

* With the potential for widespread snowfall due to low snow levels
  in both the mountains and valleys, and this being the first
  potential for snowfall "down here" this cold season, we have
  issued a Winter Storm Watch for western NV, northeastern CA, and
  the Sierra Wednesday evening-Thursday night.

* At this time, the cold front and main snow band look to move
  through the area Wednesday night into Thursday morning, with
  residual snow showers continuing into the afternoon on Thursday.
  Lake-effect snows are also possible east/south of larger area
  lakes, especially Thursday afternoon/evening into Friday morning.

* The probability of seeing a least 1" of snowfall in the lower
  valleys along the US-395 corridor is nearly 85%, and about 40%
  for 2", which would result in travel impacts. Sierra communities
  have a 30-40% chance for 6" of snowfall. Due to the mesoscale
  nature of the snow band, the details of the amount of snowfall
  and location will become better known in the next 12-18 hours.
  Potential lake-effect snowfall Thursday evening is not included
  in these probabilities.

-Cold temperatures:

* After the cold front passes Thursday, temperatures will plummet 15-
  20 degrees, with Friday and Saturday looking quite cold,
  especially in areas that receive snowfall. High temperatures
  Friday in western NV and Sierra valleys look to be in the 30s.
  Frigid temperatures are possible Friday night into Saturday
  morning, with teens and single digits possible for western NV
  valleys, and single digits to subzero temperatures in the Sierra.

* Below-average temperatures are expected this coming weekend with
  another storm possible early next week. Quite a few simulations
  show a slow-moving series of winter storms next week. There is
  a lot of variability in model solutions, but there is potential
  for significant amounts of snow in many areas and prolonged
  travel disruptions. We will continue to keep our eye on it.

-Johnston

&&

.AVIATION...

VFR conditions will prevail through the early evening hours with generally
light winds out of the west. However, virga and gusty ridge top
winds on the order of 50-60 kts will yield both mountain
obscurations and some mountain wave turbulence on the lee side of
ranges. Showers will begin to move into the region later this
afternoon or early evening, generally impacting terminals along
and south of a Portola/Lovelock line. While precip type will
mostly be RA, some brief mixture cannot be completely ruled out at
TRK and TVL around midnight. MMH will generally be a mixture or
all SN later tonight through the morning hours. Some uncertainty
remains about the impact precipitation will have on FG and low
stratus late overnight into tomorrow morning. At this time, will
keep MVFR cigs for RNO/CXP/MEV along with IFR vsby over the Sierra
terminals. Lower restrictions may be necessary with the 00Z or
06Z issuance, however. -Dustin

&&

.REV Watches/Warnings/Advisories...
NV...Winter Storm Watch from Wednesday evening through Thursday
     evening NVZ001-003-004.

     Winter Storm Watch from Wednesday afternoon through Thursday
     afternoon NVZ005.

     Winter Storm Watch from Wednesday afternoon through Thursday
     evening NVZ002.

CA...Winter Storm Watch from Wednesday afternoon through Thursday
     afternoon CAZ070-071.

     Winter Storm Watch from Wednesday evening through Thursday
     evening CAZ073.

     Winter Storm Watch from Wednesday afternoon through Thursday
     evening CAZ072.

&&

For more information from the National Weather Service visit...
http://weather.gov/reno