Alert archive / Wyoming / Winter Storm Warnings in 2018

Winter Storm Warning 4, NWS Riverton, WY

February 4, 20184 counties in Wyoming

NWS Riverton, WY issued this winter storm warning at Feb 4, 2018, 1:25 AM MST for 4 counties in Wyoming. It took effect at Feb 4, 2018, 2:00 PM MST. It was in force for 14 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Feb 4, 2018, 1:25 AM MST (08:25 UTC)
In effect from
Feb 4, 2018, 2:00 PM MST
Expired
Feb 5, 2018, 3:43 AM MST
In force
14 hr
Issued by
NWS Riverton, WY

Counties Fremont County, WY, Lincoln County, WY, Sublette County, WY, Teton County, WY

The radar

The Riverton/Lander radar (KRIW), 120 km from the middle of the area, began a volume at 08:25 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Riverton, WY (KRIW), launched 00:00Z, 8.4 hours before the alert went out and 126 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Riverton, WY at 00:00Z on 2018-02-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Riverton, WY at 00:00Z on 2018-02-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 227 square meters per square second.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1955 m above ground
0-6 km bulk shear
95 kt
0-1 km storm-relative helicity
227 m²/s²
0-3 km storm-relative helicity
243 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

967 
WWUS45 KRIW 040825
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
125 AM MST Sun Feb 4 2018

...Continued snowfall expected across the Bighorn Mountains and 
Johnson County this morning...

...Significant snowfall expected across the Western Mountains
tonight into Monday morning...

WYZ012-042100-
/O.NEW.KRIW.WS.W.0004.180204T2100Z-180205T1500Z/
Teton and Gros Ventre Mountains-
125 AM MST Sun Feb 4 2018

...WINTER STORM WARNING IN EFFECT FROM 2 PM THIS AFTERNOON TO
8 AM MST MONDAY...

* WHAT...Heavy snow and blowing snow expected. Plan on difficult
  travel conditions. Total snow accumulations of 12 to 16 inches,
  with localized amounts up to 20 inches, are expected.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 45 mph will 
  cause areas of blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing snow means severe
winter weather conditions are expected. 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.

$$

WYZ001-002-042100-
/O.NEW.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
125 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY IN EFFECT FROM 2 PM THIS AFTERNOON TO
8 AM MST MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road
  conditions. In addition, areas of poor visibility are expected.
  Total snow accumulations of 6 to 12 inches in the mountains with
  4 to 6 inches in the lower elevations except only 2 to 4 inches
  around Mammoth.

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

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 50 mph will cause
  areas of blowing and drifting snow especially in the Absaroka
  Mountains.

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.

$$

WYZ024-042100-
/O.NEW.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Salt River and Wyoming Ranges-
125 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY IN EFFECT FROM 2 PM THIS AFTERNOON TO
8 AM MST MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road
  conditions and areas of poor visibility. Total snow
  accumulations of 4 to 10 inches, with localized amounts up to 15 
  inches, are expected.

* WHERE...Salt River and Wyoming Ranges.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 45 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.

$$

WYZ008-009-041900-
/O.CON.KRIW.WW.Y.0007.000000T0000Z-180204T1900Z/
Bighorn Mountains West-Bighorn Mountains Southeast-
125 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL NOON MST
TODAY...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and areas of poor visibility. Additional snow 
  accumulations of 3 to 5 inches, with localized amounts up to 7 
  inches, are expected.

* WHERE...Bighorn Mountains.

* WHEN...Until noon today.

* ADDITIONAL DETAILS...Winds gusting as high as 30 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.

$$

WYZ010-011-041600-
/O.CON.KRIW.WW.Y.0007.000000T0000Z-180204T1600Z/
Northeast Johnson County-Southeast Johnson County-
Including the cities of Buffalo and Kaycee
125 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 9 AM MST THIS
MORNING...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions andareas of poor visibility. Additional snow 
  accumulations of up to two inches are expected.

* WHERE...Johnson County.

* WHEN...Until 9 AM today.

* ADDITIONAL DETAILS...Winds gusting as high as 35 mph will 
  cause areas of blowing and drifting snow. Cold wind chills as 
  low as 20 below zero will cause frostbite in as little as 30 
  minutes to exposed skin.

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.

$$

For more information from the National Weather Service visit
http://weather.gov/riw
5 follow-up statements
130 
WWUS45 KRIW 041559
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
859 AM MST Sun Feb 4 2018

...Continued snowfall expected across the Bighorn Mountains this 
morning...

...Significant snowfall expected across the Western Mountains
tonight into Monday morning...

WYZ010-011-041700-
/O.EXP.KRIW.WW.Y.0007.000000T0000Z-180204T1600Z/
Northeast Johnson County-Southeast Johnson County-
Including the cities of Buffalo and Kaycee
859 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY WILL EXPIRE AT 9 AM MST THIS MORNING...

Light snowfall with little accumulation expected today.

$$

WYZ012-041900-
/O.CON.KRIW.WS.W.0004.180204T2100Z-180205T1500Z/
Teton and Gros Ventre Mountains-
859 AM MST Sun Feb 4 2018

...WINTER STORM WARNING REMAINS IN EFFECT FROM 2 PM THIS
AFTERNOON TO 8 AM MST MONDAY...

* WHAT...Heavy snow and blowing snow expected. Plan on difficult 
  travel conditions. Total snow accumulations of 12 to 16 inches,
   with localized amounts up to 20 inches, are expected.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 45 mph will 
  cause areas of blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing snow means severe
winter weather conditions are expected. 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.

$$

WYZ008-009-041900-
/O.CON.KRIW.WW.Y.0007.000000T0000Z-180204T1900Z/
Bighorn Mountains West-Bighorn Mountains Southeast-
859 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL NOON MST
TODAY...

* WHAT...Snow and blowing snow occurring. Plan on slippery road 
  conditions and areas of poor visibility. Additional snow 
  accumulations of 3 to 5 inches, with localized amounts up to 7 
  inches, are expected.

* WHERE...Bighorn Mountains.

* WHEN...Until noon today.

* ADDITIONAL DETAILS...Winds gusting as high as 30 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.

$$

WYZ001-002-041900-
/O.CON.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
859 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 2 PM THIS
AFTERNOON TO 8 AM MST MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road 
  conditions. In addition, areas of poor visibility are 
  expected. Total snow accumulations of 6 to 12 inches in the 
  mountains with 4 to 6 inches in the lower elevations except 
  only 2 to 4 inches around Mammoth.

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

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 50 mph will 
  cause areas of blowing and drifting snow especially in the 
  Absaroka Mountains.

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.

$$

WYZ024-041900-
/O.CON.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Salt River and Wyoming Ranges-
859 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 2 PM THIS
AFTERNOON TO 8 AM MST MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road 
  conditions and areas of poor visibility. Total snow 
  accumulations of 4 to 10 inches, with localized amounts up to 
  15 inches, are expected.

* WHERE...Salt River and Wyoming Ranges.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 45 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.

$$

For more information from the National Weather Service visit
http://weather.gov/riw
274 
WWUS45 KRIW 041853
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
1153 AM MST Sun Feb 4 2018

...Significant snowfall expected across the Western Mountains 
tonight into Monday morning...

WYZ008-009-042000-
/O.EXP.KRIW.WW.Y.0007.000000T0000Z-180204T1900Z/
Bighorn Mountains West-Bighorn Mountains Southeast-
1153 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY WILL EXPIRE AT NOON MST TODAY...

Light snowfall with accumulations of an inch or two can be
expected through the afternoon. 

$$

WYZ012-042300-
/O.CON.KRIW.WS.W.0004.180204T2100Z-180205T1500Z/
Teton and Gros Ventre Mountains-
1153 AM MST Sun Feb 4 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 8 AM MST MONDAY...

* WHAT...Heavy snow and blowing snow expected. Plan on difficult 
  travel conditions. Total snow accumulations of 12 to 16 inches,
   with localized amounts up to 20 inches, are expected.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 45 mph will 
  cause areas of blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing snow means severe
winter weather conditions are expected. 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.

$$

WYZ001-002-042300-
/O.CON.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
1153 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road 
  conditions. In addition, areas of poor visibility are 
  expected. Total snow accumulations of 6 to 12 inches in the 
  mountains with 4 to 6 inches in the lower elevations except 
  only 2 to 4 inches around Mammoth.

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

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 50 mph will 
  cause areas of blowing and drifting snow especially in the 
  Absaroka Mountains.

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.

$$

WYZ024-042300-
/O.CON.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Salt River and Wyoming Ranges-
1153 AM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road 
  conditions and areas of poor visibility. Total snow 
  accumulations of 4 to 10 inches, with localized amounts up to 
  15 inches, are expected.

* WHERE...Salt River and Wyoming Ranges.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 45 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.

$$

For more information from the National Weather Service visit
http://weather.gov/riw
719 
WWUS45 KRIW 042021
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
121 PM MST Sun Feb 4 2018

...Significant snowfall expected across the Western and Northern 
Mountains tonight into Monday morning...

WYZ012-051000-
/O.CON.KRIW.WS.W.0004.180204T2100Z-180205T1500Z/
Teton and Gros Ventre Mountains-
121 PM MST Sun Feb 4 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 8 AM MST MONDAY...

* WHAT...Heavy snow and blowing snow expected. Plan on difficult
  travel conditions. Damage to power lines is possible. Total 
  snow accumulations of 8 to 11 inches, with localized amounts up 
  to 19 inches, are expected.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 55 mph will 
  cause areas of blowing and drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow and blowing snow means severe
winter weather conditions are expected. 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.

$$

WYZ008-009-051000-
/O.EXA.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Bighorn Mountains West-Bighorn Mountains Southeast-
121 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 8 AM MST MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road
  conditions. In addition, areas of poor visibility are expected.
  Total snow accumulations of 4 to 7 inches, with localized 
  amounts up to 12 inches, are expected.

* WHERE...Bighorn Mountains West and Bighorn Mountains Southeast.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 55 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.

$$

WYZ014-015-051000-
/O.EXA.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Wind River Mountains West-Wind River Mountains East-
121 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 8 AM MST MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road
  conditions. In addition, significant reductions in visibility
  are expected. Total snow accumulations of 4 to 7 inches, with
  localized amounts up to 12 inches, are expected.

* WHERE...Wind River Mountains West and Wind River Mountains 
  East.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 60 mph will cause
  widespread 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.

$$

WYZ001-002-051000-
/O.CON.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
121 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road
  conditions. In addition, areas of poor visibility are expected.
  Total snow accumulations of 4 to 7 inches, with localized
  amounts up to 12 inches, are expected.

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

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 60 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.

$$

WYZ024-051000-
/O.CON.KRIW.WW.Y.0008.180204T2100Z-180205T1500Z/
Salt River and Wyoming Ranges-
121 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow expected. Plan on slippery road
  conditions. In addition, areas of poor visibility are expected.
  Total snow accumulations of 4 to 7 inches, with localized
  amounts up to 12 inches, are expected.

* WHERE...Salt River and Wyoming Ranges.

* WHEN...2 PM today to 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 60 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.

$$

For more information from the National Weather Service visit
http://weather.gov/riw
348 
WWUS45 KRIW 050507
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
1007 PM MST Sun Feb 4 2018

...Continued snowfall expected across the Western and Northern 
Mountains until mid morning Monday...

WYZ012-051500-
/O.CON.KRIW.WS.W.0004.000000T0000Z-180205T1500Z/
Teton and Gros Ventre Mountains-
1007 PM MST Sun Feb 4 2018

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 8 AM MST MONDAY...

* WHAT...Heavy snow and blowing snow occurring. Plan on difficult
  travel conditions. Additional snow accumulations of 7 to 10 
  inches are expected.

* WHERE...Teton and Gros Ventre Mountains.

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 55 mph will 
  cause areas of 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.

$$

WYZ001-002-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
1007 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and areas of poor visibility. Additional snow 
  accumulations of 3 to 6 inches are expected.

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

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 60 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.

$$

WYZ024-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Salt River and Wyoming Ranges-
1007 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and areas of poor visibility. Additional snow 
  accumulations of 4 to 7 inches, with localized amounts up to 9 
  inches, are expected.

* WHERE...Salt River and Wyoming Ranges.

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 60 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.

$$

WYZ008-009-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Bighorn Mountains West-Bighorn Mountains Southeast-
1007 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and areas of poor visibility. Additional snow 
  accumulations of 2 to 4 inches, with localized amounts up to 7 
  inches, are expected.

* WHERE...Bighorn Mountains.

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 55 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.

$$

WYZ014-015-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Wind River Mountains West-Wind River Mountains East-
1007 PM MST Sun Feb 4 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST
MONDAY...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and significant reductions in visibility. Additional
  snow accumulations of 3 to 6 inches, with localized amounts up 
  to 9 inches, are expected.

* WHERE...Wind River Mountains.

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Winds gusting as high as 70 mph will 
  cause widespread 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.

$$

For more information from the National Weather Service visit
http://weather.gov/riw
345 
WWUS45 KRIW 051043
WSWRIW

URGENT - WINTER WEATHER MESSAGE
National Weather Service Riverton WY
343 AM MST Mon Feb 5 2018

...Continued snowfall expected across the Northwestern and 
Northern Mountains until mid morning Today...

WYZ012-051145-
/O.CAN.KRIW.WS.W.0004.000000T0000Z-180205T1500Z/
Teton and Gros Ventre Mountains-
343 AM MST Mon Feb 5 2018

...WINTER STORM WARNING IS CANCELLED...

Snowfall has diminished rapidly in most areas across the Tetons
and Gros Ventre Mountains. Thus the winter storm warning has been
cancelled. However there will still be scattered snow showers 
today with additional snowfall expected along with severely 
reduced visibility at times.

$$

WYZ024-051145-
/O.CAN.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Salt River and Wyoming Ranges-
343 AM MST Mon Feb 5 2018

...WINTER WEATHER ADVISORY IS CANCELLED...

Snowfall has diminished rapidly in most areas across the Salt
River and Wyoming Ranges. Thus the winter weather advisory has 
been cancelled. However there will still be scattered snow showers
today with additional snowfall expected along with severely 
reduced visibility at times.

$$

WYZ001-002-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Yellowstone National Park-Absaroka Mountains-
Including the cities of Lake, Mammoth, and Old Faithful
343 AM MST Mon Feb 5 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST THIS
MORNING...

* WHAT...Snow and blowing snow occurring especially across the
  northeastern sections of Yellowstone, and much of the Absaroka
  Mountains. Plan on slippery road conditions and areas of poor
  visibility. Additional snow accumulations of 3 to 6 inches are 
  expected.

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

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Strong winds 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.

$$

WYZ008-009-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Bighorn Mountains West-Bighorn Mountains Southeast-
343 AM MST Mon Feb 5 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST THIS
MORNING...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and areas of poor visibility across mountain passes.
  Additional snow accumulations of 2 to 4 inches, with localized 
  amounts up to 7 inches, are expected.

* WHERE...Bighorn Mountains.

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Strong winds 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.

$$

WYZ014-015-051500-
/O.CON.KRIW.WW.Y.0008.000000T0000Z-180205T1500Z/
Wind River Mountains West-Wind River Mountains East-
343 AM MST Mon Feb 5 2018

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 AM MST THIS
MORNING...

* WHAT...Snow and blowing snow occurring. Plan on slippery road
  conditions and significant reductions in visibility. Additional
  snow accumulations of 3 to 6 inches, with localized amounts up
  to 9 inches, are expected. However only 1 to 2 inches is
  expected along South Pass.

* WHERE...Wind River Mountains.

* WHEN...Until 8 AM Monday.

* ADDITIONAL DETAILS...Strong winds 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.

$$

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

What forecasters said that day

The local office's own words before this winter storm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Riverton, WY wrote its last area forecast discussion before this winter storm warning went out at Feb 3, 10:55 PM MST, 2 hours 30 minutes earlier.

Area forecast discussion, Feb 3, 10:55 PM MST, 2 hours 30 minutes before
Area Forecast Discussion
National Weather Service Riverton WY
1055 PM MST Sat Feb 3 2018

.SHORT TERM...Tonight through Tuesday

Quite an active period in store across the area. At the time I write
this, there is only light precipitation around the area. However,
this will change as an Arctic front drops toward the area from
the north and east. This is bringing a tight pressure gradient
across the area along with some strong winds, especially across
Sweetwater County as well as the Wind River Basin. High winds are
not expected except for maybe an isolated gust. It has mixed out
some of the basins though.

Snow will begin to pick up across the north tonight and drift south,
with the worst expected from around midnight until around dawn on
Sunday. With the expected dual impacts of wind and snow on
Interstate 25, we have expanded the winter weather advisory farther
south to include all of Johnson County. Elsewhere, we have held
off on highlights. There will be some snow in the Big Horn Basin
and Cody Foothills. However, all the models keep the QPF fairly
low. If any spot gets advisory level snow it would be areas along
and east of Shell and Ten Sleep. We will stick to a special
weather statement in the Big Horn Basin. It is the same situation
in the western mountains. Some snow will return but most should
be of the light to moderate variety. A few locations may get close
to advisory amounts but these would be in the higher elevations
and have little impact except for fresh powder on the ski slopes.

There is still some question how far south the accumulating snow can
get. Natrona County will likely see some snow but amounts should
remain light. Areas like Riverton and Lander may not get much at
all.

This snow should end Sunday morning east of the Divide. The next
question is temperatures. There could be a LARGE spread across the
area. Areas like Buffalo will certainly be cold. There is still
uncertainty how far south the cold air can get though. As a
result, we kept temperatures fairly close to continuity.

Another system will then move in Sunday night into Monday. This
looks to bring the heavier snow to the west so some highlights will
likely be needed for this time frame, more than likely advisories.
Meanwhile, most areas east of the Divide most should see most of
the precipitation hold off until Monday. At this point, the models
continue to focus on eastern areas from Johnson County into
Natrona County for the heaviest snow with less farther west.
However, there could be some snow banding that would bring locally
heavier amounts. These are impossible to pinpoint this far out
though.

Most of the steady snow should end late Monday. Ridging will then
slowly build across the area and bring drier weather into Tuesday.
There could be a few orographic showers but nothing of consequence.
It could end up being completely dry as well since the models trend
to overdue POPS and QPF in these situations.

.LONG TERM...Tuesday Night through Saturday

Forecast models are in generally good agreement with the overall
evolution of the synoptic pattern. Medium-range period begins with
northwest flow aloft prevailing through at least Wednesday night.
Conditions will be dry and relatively mild Wednesday and likely into
Thursday. West Coast ridge breaks down Thursday into Friday with a
trough set to slide southeast across the Intermountain West and
northern Rockies. ECMWF has trended slightly faster in bringing this
feature through the forecast area late in the day Thursday, but this
trend has slowed with the 12Z/Sat run. Trough will sweep across
the area Thursday night and Friday accompanied by an Arctic front.
Have increased blended west-southwest wind speeds and gusts
Thursday afternoon ahead of the front. Did the same with post-
frontal northerly winds Thursday night and Friday morning,
particularly across northern Wyoming. Favorable mid-level
temperatures coupled with the front and upper-level dynamics could
set the stage for accumulating snowfall in the basins east of the
Continental Divide. We are a long ways out, but the scenario
looks plausible. Have substantially increased mountain snow
chances in the north along with basin snow chances east of the
Divide between 00Z/Fri and 12Z/Fri. Best chances would likely be
across the northern-third of the forecast area and in upslope
favored central areas. High temperatures will be colder by at
least 10-15F Friday behind the front. If the main energy stays
just to our west, the front could very well sweep through
southwest Wyoming. The snow and clouds will clear from north-to-
south later Friday into Friday evening. Thus, temperatures Friday
night could be several degrees colder than currently forecast if
there is fresh snow cover. Similarly, rebounding temperatures
Saturday may be too optimistic given a colder start and fresh snow
cover. Drier northwest flow returns for Saturday with dry
conditions prevailing.

&&

.AVIATION...

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

Some snow overnight through midday Sunday in the western mountains.
Snow is forecast to increase in coverage during Sunday afternoon
through Sunday night. Areas of MVFR conditions will become
widespread after 21Z Sunday with IFR conditions by 00Z Monday. KJAC
will see mainly rain through 06Z Monday MVFR conditions for the most
part. Southwest WY will see VFR conditions through the period. Windy
conditions will continue at KRKS through the period. Mountain tops
will be obscured throughout the forecast period.

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

Low clouds and some light snow will occur east of the divide through
18Z Sunday mainly from a KCOD to KCPR line. Expect MVFR/IFR
conditions in these areas until 18Z. Then most places will have
ceilings rise to VFR by 21Z. Have kept KLND and KRIW with VFR
conditions through the period.

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

&&

.FIRE WEATHER...

A front will drop south across Wyoming tonight into Sunday and
bring some snow, heaviest in the north and west. Strong winds will
continue in portions of central and southern Wyoming into tonight
before decreasing. Drier and cooler weather will return to all
areas Sunday afternoon except for the west which could see
moderate to heavy snow Sunday night into Monday morning. Mixing
and smoke dispersal will range from good in portions of Sweetwater
County to fair to poor elsewhere.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory until noon MST Sunday for WYZ008-009.

Winter Weather Advisory until 9 AM MST Sunday for WYZ010-011.

&&

SHORT TERM...Hattings
LONG TERM...Jones
AVIATION...AR
FIRE WEATHER...Hattings
Hazardous weather outlook, Feb 3, 3:46 AM MST, 21 hours 39 minutes before
Hazardous Weather Outlook
National Weather Service Riverton WY
346 AM MST Sat Feb 3 2018

WYZ001>020-022>030-041230-
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-
346 AM MST Sat Feb 3 2018

...Winter Weather Advisory from this afternoon through Sunday
morning for the Big Horn Mountains and the lower elevations of
northern Johnson County...

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight

Significant snowfall expected across portions of northern
Wyoming later this afternoon into tonight. A cold front will push
south into areas east of the divide this evening, with the
coldest air expected in Johnson County. Strong west winds are
also expected across Sweetwater County today.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Sunday and Monday...Significant snowfall expected to extend into
Sunday morning across portions of northern Wyoming. Then another
round of significant snowfall is expected across western and
northern Wyoming Sunday afternoon into Monday. On Monday the
snowfall will spread south into central Wyoming east of the
divide.

Thursday and Friday...A chance of snow across northwest and
extreme northern Wyoming Thursday spreading southward Thursday
night, before ending on Friday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report any new snow amounts as well as
any wind gusts of 45 mph or greater. Thank you.

TEAM RIVERTON

In the hours before

Special weather statement, Feb 3, 8:09 PM MST, 5 hours 16 minutes before
Special Weather Statement
National Weather Service Riverton WY
809 PM MST Sat Feb 3 2018

WYZ003-004-006-041100-
Cody Foothills-North Big Horn Basin-Southeast Big Horn Basin-
Including the cities of Cody, Meeteetse, and Worland
809 PM MST Sat Feb 3 2018

Some light snow will occur at times tonight. Snowfall of a trace
to as much as 2 inches may occur. Locally higher snow amounts are
possible east of Greybull and Worland. Travelers are urged to
watch for slick roads as well as reduced visibility.

WYZ001-002-012-024-041100-
Yellowstone National Park-Absaroka Mountains-
Teton and Gros Ventre Mountains-Salt River and Wyoming Ranges-
Including the cities of Lake, Mammoth, and Old Faithful
809 PM MST Sat Feb 3 2018

Periods of snow will occur tonight. Expect 3 to 6 inches of snow
in many locations with locally higher amounts. In addition, winds
gusting up to 30 to 40 mph will bring areas of blowing and
drifting snow in the Absaroka mountains. Travelers are urged to
watch for slick roads as well as reduced visibility, including
Teton and Togwotee passes.

WYZ013-041100-
Jackson Hole-
Including the city of Jackson
809 PM MST Sat Feb 3 2018

A mix of rain and snow will change to snow after midnight.
Expect 1 to 3 inches of snow, with the best chance of 3 inches of
snow around Moran. Travelers are urged to watch for slick roads
as well as reduced visibility.
Special weather statement, Feb 4, 1:11 AM MST, 14 minutes before
Special Weather Statement
National Weather Service Riverton WY
111 AM MST Sun Feb 4 2018

WYZ003-004-006-041700-
Cody Foothills-North Big Horn Basin-Southeast Big Horn Basin-
Including the cities of Cody, Meeteetse, and Worland
111 AM MST Sun Feb 4 2018

Areas of light snow will occur through mid-morning across the Big Horn
Basin. The best chance of snow will occur northeast of a Cody to Worland
line. Total snowfall from just a dusting to 2 inches is expected. Locally
higher amounts could occur east of Greybull and Worland. Travelers
are urged to watch for slick roads as well as reduced visibility.

21
Special weather statement, Feb 4, 1:14 AM MST, 11 minutes before
Special Weather Statement
National Weather Service Riverton WY
114 AM MST Sun Feb 4 2018

WYZ013-023-042200-
Jackson Hole-Star Valley-
Including the cities of Jackson, Afton, Alpine,
Star Valley Ranch, and Thayne
114 AM MST Sun Feb 4 2018

Rain across Jackson Hole and Star Valley is expected to change to
mainly snow shortly after midnight Sunday night. 1 to 3 inches of
snow could accumulate by noon Monday with the highest amounts
over northern Jackson Hole. If your plans have you going into the
mountains Sunday night, expect much worse winter conditions.

WYZ025-042200-
Upper Green River Basin Foothills-
Including the city of Pinedale
114 AM MST Sun Feb 4 2018

Periods of snowfall is expected across the Upper Green River
Basin Sunday night, with the heaviest snowfall occurring between
midnight and 6 AM Monday. 1 to 3 inches of new snow is expected
around Pinedale and Daniel while up to 4 inches could occur near
Bondurant.

WYZ014-015-042200-
Wind River Mountains West-Wind River Mountains East-
114 AM MST Sun Feb 4 2018

Periods of snow, moderate at times are expected Sunday night across
the Wind River Mountains. The heaviest snowfall will occur across
the northern part of the range where 4 to 8 inches of snowfall
could occur. South Pass could see some snowfall late Sunday night,
but only 1 to 2 inches are expected in that area.

21

The office that day

Everything else NWS Riverton, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 4, 1:25 AM MSTWinter Weather AdvisoryRIWBig Horn, Fremont, Hot Springs, Johnson, Lincoln, Natrona and 4 more40 hr

Nearby

Winter Storm Warnings in Wyoming, 2018Every winter storm warning in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.