A potent area of low pressure developed in the Lee of the Colorado Rockies and brought heavy snow and strong wind to portions of western and central Wyoming. The hardest hit areas were Johnson, Natrona and Sweetwater Counties.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS RIW wrote it up.
A potent area of low pressure developed in the Lee of the Colorado Rockies and brought heavy snow and strong wind to portions of western and central Wyoming. The hardest hit areas were Johnson, Natrona and Sweetwater Counties. The heaviest snow fell in Natrona County. Portions of Casper Mountain received over 2 feet of snow with the city of Casper getting anywhere from 9 to 18 inches. Across Sweetwater County, 6 to 10 inches of snow was common. The snow combined with winds gusting over 50 mph to bring sharply reduced visibility and the closure of many roads, including Interstates 25 and 80.
The local office's own words before the first event, 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 the first event at Mar 12, 10:50 PM MST, 1 hour 10 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1150 PM MDT Tue Mar 12 2019 .SHORT TERM...(This evening through Wednesday night) Issued at 140 PM MDT Tue Mar 12 2019 Current forecast is on track for a major storm system to develop over Colorado tonight and combine with a weak system moving in from the Pacific Northwest to bring snow and wind to most of the forecast area. The biggest impacts will be noticed from a line from Rock Springs to Buffalo and areas southeastward. A seasonal day today will see increasing clouds from the south this evening. Northerly flow will develop over Sweetwater County around midnight with light snow falling from Kemmerer to Wamsutter overnight. By 6am wednesday morning, the surface pressure gradient across WY will strengthen considerable as the models are indicating a 980 mb surface low deepening in SW Colorado. With the NW weather system moving into western WY and the CO low strengthening by 6am, snow will spread across much of the area Wednesday morning and throughout the day. At this time, it appears that the higher snow amounts will be across Sweetwater County with 6 to 10 inches and into Natrona County, where the lower elevations should also see 6 to 10 inches and Casper Mountain should see 18 to 24 inches. See the Winter Storm Warning product (WSWRIW) for more details. In addition Lander and South Pass should see 4 to 8 inches. Some areas in Johnson County could also see 4 to 8 inches, but shadowing may result in lower amounts. During the day on Wednesday with a 20-25 mb surface pressure gradient across the state, north winds will strengthen to 25 to 35 mph with gusts of 40 to 50 mph. These strong winds combined with the snow will create very hazardous conditions across most of the area on Wednesday and into early Thursday morning. Other areas will see 1 to 3 inches of snow with winds 20 to 30 mph as well. For more information on other areas, see the advisory information in the Winter Storm Warning product (WSWRIW). It appears that most of the snow will move out of the area around 12am (midnight) Thursday, with snow continuing though from Johnson into Natrona county through 6am. Brisk northwest wind will continue through Thursday morning until the early afternoon hours. Both the NAM and the GFS are pretty good agreement with this system, including the strength of the winds and the snowfall amounts. .LONG TERM...(Thursday through Tuesday) The extended forecast models are indicative of continuing the trending of building an upper ridge of high pressure across the Intermountain West and Rockies. The extended models seem to again want to indicate subtle clipper systems moving across the area east of the Continental Divide through the extended forecast period. At this time, it still looks like there will not be much if any impact on our forecast area. Temps will slowly warm to nearly normal temps across the forecast area through the beginning of next week with a dry period expected. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1149 PM MDT Tue Mar 12 2019 Radar was showing snow increasing along and east of a 50SM E KRKS-50SM W KCPR line late Tuesday evening. This area of snow along with widespread IFR conditions, will continue to expand north and west through 15z Wednesday filling in to a KRKS-KLND- KSHR line and east. Areas of MVFR/IFR conditions will also develop further north into KCOD and KWRL 15z-18z. These conditions are expected to persist through 00z Thursday. Drier air will then gradually push in from the north 03z-12z Thursday with most conditions improving into MVFR or low VFR range with the exception of KCPR where IFR conditions are likely to remain through 12z Thursday. Further west, scattered to numerous snow showers will spread into far western Wyoming and the western mountains 08z-12z Wednesday with mountains becoming increasingly obscured and MVFR conditions developing vicinity KJAC, KBPI and KPNA. There will be only slow improvements to the terminals after 21z Wednesday. Ceilings should mostly lift into low VFR range at KJAC, KBPI, KPNA through Wednesday evening with higher mountains remaining mostly obscured. && .FIRE WEATHER... Issued AT 125 PM MDT Tue Mar 12 2019 Seasonal weather conditions will continue for the rest of the day and into the evening, with late afternoon temperatures warming nicely and breezy conditions across central WY and the northern Bighorn Basin. Clouds will be increasing across southern WY as a major winter storm system develops over Colorado tonight and a weak weather system moves into western WY from the northwest. Wednesday will be quite stormy across most of the area, with snow starting in SW WY just after midnight and quickly moving northeast through the day. In addition, strong and cold north winds will develop by 6am over much of the area to create very hazardous conditions. Snowfall will range from only an inch in places over YNP to nearly 24 inches on Casper Mountain. This storm system will continue through 6am Thursday morning before moving eastward. Thursday will see brisk NW wind with max temperatures only around freezing. The weekend will see partly cloudy weak high pressure. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until midnight MDT Wednesday night for WYZ028>030. Winter Storm Warning until 6 AM MDT Thursday for WYZ019-020-022. Winter Weather Advisory from 6 AM Wednesday to midnight MDT Wednesday night for WYZ003-005-007-008-015-017-018. Winter Storm Warning from 6 AM Wednesday to 6 AM MDT Thursday for WYZ009>011. Winter Weather Advisory until midnight MDT Wednesday night for WYZ027. && SHORT TERM...McDonald LONG TERM...Troutman AVIATION...Meunier FIRE WEATHER...McDonald
Hazardous Weather Outlook National Weather Service Riverton WY 1139 AM MDT Tue Mar 12 2019 WYZ001>020-022>030-131200- 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- 1139 AM MDT Tue Mar 12 2019 ...Winter Storm Warnings and Advisories are in effect from early Wednesday morning through Thursday morning for much of western and central Wyoming... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...This Afternoon and Tonight. Light snow will begin from eastern Sweetwater County to southern Natrona County late tonight, spreading across the rest of Sweetwater County through the rest of the night. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Wednesday and Thursday...Strong northerly winds are expected across central and eastern Wyoming Wednesday afternoon into Thursday morning. Wind gusts over 50 mph are possible over northeastern Johnson County. Scattered to numerous snow showers across the west and southwest, spreading into central Wyoming Wednesday evening and night. Significant snow accumulations along with blowing and drifting snow are possible along the Interstate 25 and 80 corridors and the South Pass area. Please see Winter Storm Warnings and Advisories for the latest information. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today. McDonald
The national radar mosaic for the moment the first event began.
7 winter storm. Local standard time, as filed.
Very heavy snow fell on Casper Mountain. The highest amount was 26 inches at the Casper Mountain SNOTEL site.
Heavy snow fell through much of Natrona County. The highest snowfall amounts were closer to Casper Mountain where 12 to 18 inches of snow fell. The Casper Airport had 14.7 inches of new snow which was the ninth snowiest day on record. Snowfall amounts diminished to around 6 inches in the western and northern portions of the county. The snow combined with winds gusting over 40 mph and brought the closure of some roads.
A trained spotter reported 10 inches of snow in Wamsutter. The snow combined with winds gusting past 40 mph to cause the closure of Interstate 80 for several hours.
Trained spotters reported anywhere from 5 to 8 inches across Rock Springs, amounts generally diminished further to the west. The snow combined with winds gusting over 40 mph to cause the closure of Interstate 80 for several hours.
Heavy snow fell in portions of the Bighorn Range. At the Little Goose SNOTEL site, 17 inches of new snow fell.
A combination of periods of snow and winds gusting past 50 mph at times brought the closure of roads, including Interstates 25 and 90.
Heavy snow fell in portions of southeastern Johnson County. The highest amount measured was 6 inches near Linch. The snow combined with winds gusting past 50 mph at times to bring near whiteout conditions and cause the closure of Interstate 25.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2019Every state in 2019This day in weather historyWarnings in Wyoming, March 2019
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 810008, 810006, 810004, 810003, 810010, 810009, 810011.