A storm system moved out of the central Rockies and into the Plains states and brought heavy snow to portions of central Wyoming. The heaviest snow fell along the eastern slopes of the Wind River Range where over a foot of new snow was common with a maximum of 27 inches at the Townsend Creek SNOTEL site.
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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 storm system moved out of the central Rockies and into the Plains states and brought heavy snow to portions of central Wyoming. The heaviest snow fell along the eastern slopes of the Wind River Range where over a foot of new snow was common with a maximum of 27 inches at the Townsend Creek SNOTEL site. In the lower elevations, the heaviest snow was in the Lander Foothills where amounts ranged from 7.7 inches at the airport to 19 inches near Sinks Canyon State Park. Other hard hit areas included northern Johnson County and the Green Mountains.
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 Apr 9, 10:56 PM MST, 1 hour 4 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1156 PM MDT Tue Apr 9 2019 .UPDATE... Issued at 947 PM MDT Tue Apr 9 2019 Decided to cancel the winter weather advisory for the far western mountains as the main energy from this storm has shifted to east of the Divide and southern areas, and additional snowfall amounts are only expected to be in the 1 to 2 inch range. The exception was to extend the western slopes of Wind River Mountains to match the east side of the Wind River Range due to the expected impacts along South Pass. The other concern with this system remains on how quickly the rain will change to snow over the central basins. Still looks like most areas will see a change over between Midnight and 6 AM. The precip at Casper still looks to change to snow by daybreak, but the heaviest axis on the latest 00Z runs show the heaviest snowfall remaining just northwest of Casper proper. && .SHORT TERM...Tonight through Friday With the contrast in the forecast, we will again split the discussion between West and East of the Divide. West of the Divide...Mainly light precipitation continues at this time across the area. Some areas saw a good amount last night, with over an inch or rain reported at some of the areas in the Jackson Valley. So far, no flooding problems though. We will leave the flood watch in effect for now, but flooding at this time appears to be becoming less likely. Snow levels will lower to the valley floors this evening in the western mountains but for the most part amounts look to remain fairly light. We will leave the advisories in effect for now mainly for impacts. The main focus will shift to the south as an upper level low moves across the area and increased moisture moves into the area. Precipitation will get going across the south along the left front quadrant of a jet streak this evening. As colder air moves in behind an advancing cold front, we will see the rain change over the snow from west to east after midnight. There may be a break Wednesday morning as some models show a bit of a dry slot drying to work into the area before filling in again Wednesday afternoon. This, combined with the gusty winds from developing low pressure moving into the plains, will likely bring some difficult travel conditions. As a result, we have issued winter weather advisories starting at midnight and running into the evening hours. Snow will slowly taper off Wednesday night as low pressure moves away to the east. Given the active weather over the first 36 hours or so, we didn't take a long look at Thursday or Friday. No big storms are expected. However, we do have some northwesterly flow that will bring mainly mountain snow showers to some areas. The models are doing the usual wet bias for orographics, so we went with mainly chance POPs with low QPF through Friday. East of the Divide...We have some showers out there right now. There could even be a couple of thunderstorms around with come decent CAPE and negative lifted indices. The main threat would be a strong wind given the strong winds aloft. Steadier precipitation will begin to spread into much of the area this evening as moisture encounter the left front quadrant of a jet streak. There are some impressive totals with the QPF, some models over an inch tonight. This is probably a bit overdone and the models are never perfect with placement, but it does look rather wet. Most of the models have narrowed down to a corridor from near Jeffrey City through Natrona and especially Johnson County. And this will play a part in effects. With colder air moving in begin a passing cold front, 700 millibar temperatures are progged to fall below minus 6 across the north by 3 am and across most of the area by sunrise. There could be a variance of an hour or two though. The x factor here will be the rate of precipitation as an extended period of very heavy rain could bring enough evaporational cooling for a earlier changeover so this has to be watched. Then on Wednesday, lee cyclogenesis will occur over Colorado and then deepen rapidly as it moves into the Plains states. This will two things. One, it will tighten the pressure gradient across the area and increase the winds. Areas favored by northerly flow will see gusty to strong winds like Buffalo, the Big Horn Basin and even the Wind River Basin. If there is a mitigating factor, it is that it is wetter snow so it won't blow quite as much. The second thing will be to bring in wrap around moisture and turn winds to favor the more northeasterly upslope locations. These include places like Casper and Lander. As for total amounts, the rule will be the further east you go, the higher the snow totals. All the models have centered around Johnson County to be the worst hit area with snow totals of a foot or possible certainly possible. The worst should end by sunset on Wednesday as the low pressure moves away to the east. Again, like West of the Divide, we didn't take a real close look at the Thursday. It looks to remain rather cool though with northwest flow and some mainly mountain showers. .LONG TERM...Friday night through Tuesday Snow showers in the west with mild temperatures Friday night and Saturday. The ECMWF model is showing drier conditions than all other models with GFS still the wettest. Most of the models are in close consensus so we will keep the shower activity going in the northwest and west for now. East of the Divide will be mainly dry, but still on the cooler side. A series of weather systems will move through the region Sunday and again late Monday. Showers in the west early Sunday will spread to the south through the day. Isolated showers will develop east of the Divide late Sunday and Monday. Monday night and Tuesday will see shower activity persist across the entire && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1141 PM MDT Tue Apr 9 2019 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Far western Wyoming including KJAC will see the worst conditions through about 18Z with a combo of MVFR/IFR at times in low ceilings and snow. However after 18Z, the far west is expected to improve with MVFR/IFR conditions becoming less likely with time. However across southern Wyoming including KRKS, persistent low ceilings and snow are likely through at least 00Z Thursday before gradually improving Wednesday night. Mountains will be obscured much of the time. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals Ongoing precipitation across central Wyoming is expected to expand across the rest of the area for the remainder of tonight. The rain in the lower elevations is expected to change to snow in most locations between 09Z and 15Z Wednesday. Widespread MVFR to IFR conditions are likely trough 00Z Thursday, before gradually improving from north to south Wednesday night. Strong north to northwest winds are expected to develop in most locations by 12Z, and continue through Wednesday evening. Mountains will be obscured through the TAF period. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Rain will spread across the state tonight and mix with and change to snow for most areas by mid morning Wednesday. Rain and snow should end in the far west late tonight and then taper off from northwest to southeast late Wednesday into Wednesday night. Gusty to strong winds will develop East of the Divide and in Sweetwater County late tonight and into Wednesday. Mixing and smoke dispersal on Wednesday will be generally good. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight MDT Wednesday night for WYZ008-027>030. Winter Storm Warning from 6 AM Wednesday to midnight MDT Wednesday night for WYZ018>020-022. Flood Watch through Wednesday morning for WYZ013-023-027. Winter Storm Warning from 3 AM Wednesday to midnight MDT Wednesday night for WYZ010-011. Winter Weather Advisory from 6 AM Wednesday to midnight MDT Wednesday night for WYZ003-005-007-017. Winter Storm Warning until midnight MDT Wednesday night for WYZ009-015. Winter Weather Advisory until midnight MDT Wednesday night for WYZ002-014. && UPDATE...Murrell SHORT TERM...Hattings LONG TERM...Swanson AVIATION...Murrell FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 1138 AM MDT Tue Apr 9 2019 WYZ001>020-022>030-101745- 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- 1138 AM MDT Tue Apr 9 2019 ...Winter Storm Warning and Winter Weather Advisories are in effect for much of western and central Wyoming... ...Flood Watch for the Jackson and Star Valleys and Southern Lincoln county through Noon Wednesday... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Far western valleys could see enough rainfall through tonight on the melting snowpack to cause some flooding. Please see flood statement for more details. Significant mountain snowfall is also possible over the western mountains through tonight. Rain will change to snow in the north late tonight. Please see winter weather statements for more details. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Wednesday...Snow likely most locations. The snow could be heaviest across southern and east central Wyoming, as well as on the north and east facing slopes of the central mountains. Gusty north wind is also expected, especially for areas east of the Divide. Again, please see winter weather products and forecasts for details. Saturday night through Sunday night...A chance of snow in the western mountains with rain or snow in the far west valleys. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The national radar mosaic for the moment the first event began.
5 winter storm. Local standard time, as filed.
Heavy snow fell along the eastern slopes of the Wind River Range. Some of the more notable amounts included 27 inches at the Townsend Creek SNOTEL site and 20 inches at the South Pass SNOTEL site.
Heavy snow fell in portions of the eastern Bighorn Mountains. At the Cloud Peak SNOTEL site 15 inches of new snow fell.
A trained spotter reported seven inches of snow about 13 miles south-southeast of Buffalo.
At the Lander Aiport, 7.7 inches of snow was measured. Around the region, amounts ranged from seven inches in Lander to 18 inches in Sinks Canyon State Park.
A trained spotter reported eight inches of snow at Jeffrey City.
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, April 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: 819410, 819411, 819412, 819413, 819414.