Winter Storm Warning 2, NWS Riverton, WY

880 
WWUS45 KRIW 121219
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
519 AM MST Fri Jan 12 2018

...More significant areas of accumulating snow along and west of
the Continental Divide through the day today...

.The Pacific weather disturbance is moving through the region.
Snow will continue through the day today. Moderate to locally
heavy snow will occur through tonight, tapering off to light snow
by mid morning.

WYZ012-130000-
/O.CON.KRIW.WS.W.0002.000000T0000Z-180113T0000Z/
Teton and Gros Ventre Mountains-
519 AM MST Fri Jan 12 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Heavy snow occurring. Plan on difficult travel
  conditions. 8 to 16 inches of snow have fallen at most mountain
  locations. Additional snow accumulations of 2 to 6 inches, with
  localized amounts up to 9 inches, are expected today.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...Until 5 PM Today.

* ADDITIONAL DETAILS...Teton Pass remained closed at 5 am this
  morning due to the snow. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow means severe winter weather
conditions are occurring. If you must travel, keep an extra
flashlight, food and water in your vehicle in case of an
emergency. The latest road conditions for the state you are
calling from can be obtained by calling 5 1 1.

$$

WYZ013-023-130000-
/O.CON.KRIW.WS.W.0002.000000T0000Z-180113T0000Z/
Jackson Hole-Star Valley-
Including the cities of Jackson, Afton, Alpine, 
Star Valley Ranch, and Thayne
519 AM MST Fri Jan 12 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Snow occurring. Plan on difficult travel conditions. 8 
  to 12 inches of snow have been reported in areas of Jackson 
  Valley. Additional snow accumulations of 1 to 3 inches are 
  expected today.

* WHERE...Jackson Hole and Star Valley.

* WHEN...Until 5 PM Today.

* ADDITIONAL DETAILS...Be prepared for significant reductions in 
  visibility at times.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow means severe winter weather
conditions are occurring. If you must travel, keep an extra
flashlight, food and water in your vehicle in case of an
emergency. The latest road conditions for the state you are
calling from can be obtained by calling 5 1 1.

$$

WYZ001-002-130000-
/O.CON.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
519 AM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Snow occurring. Plan on slippery road conditions. 3 to 5
  have been measured in the north part of the park with 6 to 15
  inches across the various snotel sites. Additional snow 
  accumulations of 1 to 3 inches, with localized amounts up to 6 
  inches, are expected today.

* WHERE...Yellowstone National Park and Absaroka Mountains.

* WHEN...Until 5 PM Today.

* ADDITIONAL DETAILS...Be prepared for reduced visibilities at 
  times.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow means periods of snow will
cause primarily travel difficulties. Be prepared for snow covered
roads and limited visibilities, and use caution while driving.
The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

$$

WYZ014-015-024-130000-
/O.CON.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Wind River Mountains West-Wind River Mountains East-
Salt River and Wyoming Ranges-
519 AM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Snow occurring. Plan on slippery road conditions. 7 to 14
  inches have been measured in the Salt and Wyoming Ranges and 6
  to 9 inches on the west side of the Wind River Range with up to
  3 inches on the east side. Additional snow accumulations of 1 
  to 4 inches, with localized amounts up to 7 inches, are 
  expected today.

* WHERE...Wind River Mountains West, Wind River Mountains East 
  and Salt River and Wyoming Ranges.

* WHEN...Until 5 PM Today.

* ADDITIONAL DETAILS...Be prepared for reduced visibilities at 
  times.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow means periods of snow will
cause primarily travel difficulties. Be prepared for snow covered
roads and limited visibilities, and use caution while driving.
The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

$$

WYZ025-130000-
/O.CON.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Upper Green River Basin Foothills-
Including the city of Pinedale
519 AM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Snow occurring. Plan on slippery road conditions. 2 to 3
  inches have been reported in Pinedale but up to a foot was
  reported on highway 191 northwest of Pinedale on the rim.
  Additional snow accumulations of up to two inches are expected
  today.

* WHERE...Upper Green River Basin Foothills.

* WHEN...Until 5 PM today.

* ADDITIONAL DETAILS...Be prepared for reduced visibilities at 
  times.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for blowing snow means that
visibilities will be limited due to strong winds blowing snow
around. Use caution when traveling, especially in open areas. The
latest road conditions for the state you are calling from can be
obtained by calling 5 1 1.

$$

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

415 
WWUS45 KRIW 122006
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
106 PM MST Fri Jan 12 2018

...More significant areas of accumulating snow along and west of
the Continental Divide through the day today...

.The Pacific weather disturbance is moving through the region.
Snow will continue through the day today. Moderate to locally
heavy snow will occur through tonight, tapering off to light snow
by mid morning.

WYZ012-130000-
/O.CON.KRIW.WS.W.0002.000000T0000Z-180113T0000Z/
Teton and Gros Ventre Mountains-
106 PM MST Fri Jan 12 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Heavy snow and blowing snow occurring. Plan on 
  difficult travel conditions, including during the evening 
  commute. Additional snow accumulations of 2 to 4 inches are 
  expected.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...Until 5 PM today.

* ADDITIONAL DETAILS...Winds gusting as high as 30 mph will 
  cause patchy blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing snow means severe
winter weather conditions are occurring. If you must travel, keep
an extra flashlight, food and water in your vehicle in case of an
emergency. The latest road conditions for the state you are
calling from can be obtained by calling 5 1 1.

$$

WYZ013-023-130000-
/O.CON.KRIW.WS.W.0002.000000T0000Z-180113T0000Z/
Jackson Hole-Star Valley-
Including the cities of Jackson, Afton, Alpine, 
Star Valley Ranch, and Thayne
106 PM MST Fri Jan 12 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Heavy occurring, including during the evening commute. 
  Additional accumulation of an inch is expected.

* WHERE...Jackson Hole and Star Valley.

* WHEN...Until 5 PM today.

* ADDITIONAL DETAILS...Slick, snow packed and icy roads will
  cause travel delays.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning means significant amounts of ice are
occurring This will make travel very hazardous or impossible. The
latest road conditions for the state you are calling from can be
obtained by calling 5 1 1.

$$

WYZ001-002-130000-
/O.CON.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
106 PM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Snow and blowing snow occurring. Plan on slippery road 
  conditions, including during the evening commute. In addition, 
  areas of poor visibility are expected. Additional snow 
  accumulations of up to two inches are expected.

* WHERE...Yellowstone National Park and Absaroka Mountains.

* WHEN...Until 5 PM today.

* ADDITIONAL DETAILS...Winds gusting as high as 35 mph will 
  cause areas of blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means periods
of snow and blowing snow will cause primarily travel
difficulties. Be prepared for snow covered roads and limited
visibilities, and use caution while driving. The latest road
conditions for the state you are calling from can be obtained by
calling 5 1 1.

$$

WYZ014-015-024-130000-
/O.CON.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Wind River Mountains West-Wind River Mountains East-
Salt River and Wyoming Ranges-
106 PM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...Snow and blowing snow occurring. Plan on slippery road 
  conditions, including during the evening commute. In addition, 
  some reductions to visibility are expected. Additional snow 
  accumulations of up to two inches are expected.

* WHERE...Wind River Mountains West, Wind River Mountains East 
  and Salt River and Wyoming Ranges.

* WHEN...Until 5 PM today.

* ADDITIONAL DETAILS...Winds gusting as high as 35 mph will 
  cause patchy blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow and blowing snow means periods
of snow and blowing snow will cause primarily travel
difficulties. Be prepared for snow covered roads and limited
visibilities, and use caution while driving. The latest road
conditions for the state you are calling from can be obtained by
calling 5 1 1.

$$

WYZ025-130000-
/O.CON.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Upper Green River Basin Foothills-
Including the city of Pinedale
106 PM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 PM MST THIS
AFTERNOON...

* WHAT...occurring, including during the evening commute. 
  Additional accumulation of an inch is expected.

* WHERE...Upper Green River Basin Foothills.

* WHEN...Until 5 PM today.

* ADDITIONAL DETAILS...Slick, snow packed and icy roads will
  cause travel delays.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for blowing snow means that
visibilities will be limited due to strong winds blowing snow
around. Use caution when traveling, especially in open areas. The
latest road conditions for the state you are calling from can be
obtained by calling 5 1 1.

$$

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

323 
WWUS45 KRIW 130005
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
505 PM MST Fri Jan 12 2018


WYZ012-013-023-130115-
/O.EXP.KRIW.WS.W.0002.000000T0000Z-180113T0000Z/
Teton and Gros Ventre Mountains-Jackson Hole-Star Valley-
Including the cities of Jackson, Afton, Alpine, 
Star Valley Ranch, and Thayne
505 PM MST Fri Jan 12 2018

...WINTER STORM WARNING HAS EXPIRED...

Snow has ended or become very light across the area early this
evening.

$$

WYZ001-002-014-015-024-025-130115-
/O.EXP.KRIW.WW.Y.0002.000000T0000Z-180113T0000Z/
Yellowstone National Park-Absaroka Mountains-
Wind River Mountains West-Wind River Mountains East-
Salt River and Wyoming Ranges-Upper Green River Basin Foothills-
Including the cities of Lake, Mammoth, Old Faithful, and Pinedale
505 PM MST Fri Jan 12 2018

...WINTER WEATHER ADVISORY HAS EXPIRED...

Snow has ended or become very light across the area early this
evening.


$$

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

Area Forecast Discussion
National Weather Service Riverton WY
1123 PM MST Thu Jan 11 2018

.SHORT TERM...(This evening through Sunday)
Issued at 116 PM MST Thu Jan 11 2018

...Winter Weather Advisories for most of the western mountains
and valleys until 5 pm Friday...

Imagery shows a large ewd translating trof over the wrn CONUS with
the trof axis extending from scntrl Canada into/through TX. There
are now bookend ridges over each coast with an embedded upstream
shortwave trof west of WA ovr the EPAC. Locally, the FA is under nw
flow aloft with a 110 to 140 kt jet overhead most of the region west
of the Divide and the exit portion of the jet moving through cntrl
ID towards wrn WY. The SFC has strong post frontal high pressure
from srn Canada through ern MT, ern WY and into the cntrl Plains.
Light areas of snow/flurries continue across wrn/nwrn/nrn WY.

West of the Divide: Areas of light snow or flurries continue under
jet influenced NW flow and modest to weak moisture behind
yesterday's exiting trof/front. Significant increases in
precipitation/snow this afternoon and overnight will be associated
with the embedded strong jet and associated low amplitude shortwave
arriving later this afternoon in addition to the exit region of the
jet moving over western WY. Moisture, clouds and upper level
dynamics will then increase rapidly with the heaviest
precipitation...all of it as snow this time even across the valley
floors...falling between late afternoon today to near or just after
sunrise Friday morning. By the afternoon on Friday, the area should
expect new total snowfall amounts ranging from 4 to 12 inches
(locally to 18 inches) in the Teton and Gros Ventre Mountains. The
valleys should see 2 to 6 inches of new snow with up to 8 inches
locally. South to southwest winds of 15 to 25 gusting 30 to 40 mph
this afternoon will increase to 25 to 40 mph by this evening,
gusting 45 to 60 mph at times, with the strongest gusts likely
between late evening tonight and sunrise Friday. Friday night
through Saturday, the jet and embedded upper shortwave translate ewd
and out of the FA with some clearing skies east of the divide and
across southern WY, leaving cold temperatures in place. Across the
west and northwest, nw flow aloft and modest, but decreasing,
moisture will keep low chances for light precip around. Sunday,
except for a few leftover flurries over the higher reaches of a
couple of mountains, the weather should be cool but nice with
relatively light wind for most locations.

East of the Divide: This evening and overnight, increasing brisk
(locally strong) winds will return to the foothills and Wind
Corridor once again as a prelude to the next winter system due to
arrive across western WY later today into Friday. Although winds may
gust to "high" status at a few locations, most of the area should
remain below High Wind criteria. Therefore, no High Wind Watch at
this time. Even the Wind River Basin could see some winds mixing
down from just above the SFC between late this evening and 4 or 5 AM
Friday (especially across hilly locations) with w to wnw winds
gusting 25 to 40 mph at times. However, this system will take just
enough of a north or northeastern track around the ridge to the west
(both jet and embedded shortwave) that most of the (significant)
moisture and subsequent precipitation will remain across
wrn/nwrn/nrn/nern WY. As the embedded shortwave moves across the FA
overnight tonight, all areas east of the Divide stand at least a
small chance for some light snow or flurries with The Bighorn
Mountains and, to a much lesser extent, adjacent Johnson and Natrona
Counties seeing the better chances for measurable snowfall with and
ahead of a clipper front. Not much is expected elsewhere. Friday
night through Saturday, the jet and embedded upper shortwave
translate ewd and out of the FA with some clearing skies east of the
divide and across southern WY, leaving cold temperatures in place.
Across the north, nw flow aloft and modest, but decreasing, moisture
will keep low chances for flurries around. Sunday should be cool,
dry and nice with relatively light wind for most locations.

.LONG TERM...(Sunday night through Thursday)
Issued at 116 PM MST Thu Jan 11 2018

Medium-range forecast models in relatively good agreement with the
overall evolution of the synoptic pattern through about midweek.
High-amplitude ridge will be over the western U.S. to begin the
period with the downstream central U.S. trough about to get
reinforced with another shot of cold air. Developing closed-low will
drop into the Northern Plains/Upper Midwest Sunday night and Monday.
The associated cold front will be along the Canadian border to begin
the period and will rapidly push south Sunday night. Still some
discrepancy as to how far west the very cold air will push, but
Monday will be colder than Sunday. Could certainly see a scenario
where the high temperatures Monday will need to be dropped in
Johnson and Natrona counties and the far northern Big Horn Basin.
Light snow may have a difficult time pushing any farther south and
west than about a Cody-Worland-Casper line early Monday. Have upped
precipitation chances north and east of this line from what the
blended model forecasts provided. The western ridge begins an
eastward push late Monday in response to an approaching long-wave
trough along the West Coast. The ridge axis will swing across the
forecast area Tuesday with dry conditions anticipated. Question on
Tuesday will be how far west the cold air makes it on Monday and if
it retreats east as the trough pushes across the state. A plausible
scenario is that warming in the basins will be limited as cold air
is trapped by the much warmer air moving in aloft. It is also
possible that cold air retreats east late Monday into Tuesday and
temperatures climb to above normal Tuesday. This will also depend
upon which areas get light snow accumulations early Monday. For now,
have split the difference with model guidance in the eastern zones
and am going with the idea that warmer air will reach areas west of
Johnson and Natrona counties. Shortwave energy and associated
moisture reaches western Wyoming late Tuesday night. General trend
has been to keep this energy across the northern half of the
forecast area early Wednesday and on into the afternoon. The latest
ECMWF tries to generate a closed low late Wednesday into Thursday
across Wyoming, while the GFS and GEM are much more progressive with
this system. Will stick more closely to the latter solution for
Wednesday and Wednesday night. The next wave of precipitation and
energy will likely reach the far west late Thursday with a more
zonal flow anticipated off the Pacific.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday)
Issued at 1100 PM MST Thu Jan 11 2018

West of the Continental Divide...KJAC, KBPI, KPNA, and KRKS

Snow will occur in the mountains through Friday afternoon with MVFR
to IFR conditions and frequent obscuration. The valleys will see
periods of snow through 18Z, then scattered light snow in the
afternoon. A gusty wind will occur through the day with the wind
decreasing toward 00Z Saturday. KRKS will be windy with only
scattered snow showers possible until 18Z. Conditions will improve
in the west by 00Z Saturday. However, KJAC will stay with MVFR
conditions after 00Z Saturday.

East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL

VFR conditions are anticipated through the forecast period. Windy
conditions will develop overnight and continue through Friday
afternoon with the wind decreasing after 21Z Friday. Scattered snow
showers will occur Friday morning as the weather system moves
through the area.

Please see the Aviation Weather Center and/or CWSU
ZDV and ZLC for the latest information on icing and turbulence
forecasts.

&&

.FIRE WEATHER...
Issued AT 116 PM MST Thu Jan 11 2018

The next winter weather system will be moving into western Wyoming
today. Lingering areas of light snow or flurries across the western
mountains will be replaced by moderate to locally heavy snow from
later this afternoon through Friday morning, becoming light snow in
the afternoon and evening. Winds will become gusty across the usual
spots this evening and overnight, with even the Wind River Basin
seeing gusty winds at times late tonight. Smoke dispersion will be
fair to good today and fair to very good Friday west of the
Divide...poor to fair east of the Divide both days.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST Friday for WYZ001-002-
012>015-023>025.

&&

SHORT TERM...Braun
LONG TERM...Jones
AVIATION...AR
FIRE WEATHER...Braun

Hazardous Weather Outlook
National Weather Service Riverton WY
402 AM MST Thu Jan 11 2018

WYZ001>020-022>030-121200-
Yellowstone National Park-Absaroka Mountains-Cody Foothills-
North Big Horn Basin-Southwest Big Horn Basin-
Southeast Big Horn Basin-Owl Creek and Bridger Mountains-
Bighorn Mountains West-Bighorn Mountains Southeast-
Northeast Johnson County-Southeast Johnson County-
Teton and Gros Ventre Mountains-Jackson Hole-
Wind River Mountains West-Wind River Mountains East-
Upper Wind River Basin-Wind River Basin-Lander Foothills-
Green Mountains and Rattlesnake Range-
Natrona County Lower Elevations-Casper Mountain-Star Valley-
Salt River and Wyoming Ranges-Upper Green River Basin Foothills-
Upper Green River Basin-South Lincoln County-
Rock Springs and Green River-Flaming Gorge-East Sweetwater County-
402 AM MST Thu Jan 11 2018

...Winter Weather Advisories for most of the western mountains
and valleys from this afternoon until 5 pm Friday...

This Hazardous Weather Outlook is for Western and Central
Wyoming.

.DAY ONE...Today and Tonight.

Mid afternoon today through Friday...Another upper level disturbance
will spread snow into the west, with locally heavy snow possible.
Light snow expected east of the Divide Friday morning.

Strong southwest to west winds are expected from Rock
Springs to Casper as well as along the foothills east of the
Continental Divide tonight. Strong northwest winds are expected
after midnight tonight from Dubois to Riverton.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...The snow in Western Wyoming will be decreasing in the
afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report wind gusts of 50 mph as well as
any snowfall amounts. Thank you.

TEAM RIVERTON