A Pacific storm moved into Wyoming and brought locally heavy snow and high wind. The heaviest snow fell in the Tetons where some areas received up to 2 feet of new snow.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 Pacific storm moved into Wyoming and brought locally heavy snow and high wind. The heaviest snow fell in the Tetons where some areas received up to 2 feet of new snow. Locally high winds also occurred in southern Wyoming, where Bitter Creek had sustained winds of over 40 mph for an hour and a half.
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 12, 12:42 AM MST, 2 hours 18 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 142 AM MDT Thu Apr 12 2018 .SHORT TERM...Thursday through Saturday night The complicated forecast continues today with multiple concerns. Radar shows a good amount of precipitation moving across the west with a bit moving east of the divide as well. Web cams are showing decent snow in places like Teton Pass as well so at this point the warnings will continue as is. The front is still in Idaho, so any precipitation East of the Divide with the exception of the mountains will likely fall as rain for the most part. In addition, southwesterly flow will increase ahead of the front bringing breezy to windy conditions to many locations. Although it may be borderline, we went ahead an upgraded the high wind watches to warnings from Sweetwater through Natrona Counties for this afternoon and this evening. A few locations, like the Wind River Basin could see a brief period of strong winds as well as flow turns northwesterly following the frontal passage later this afternoon as well. A special weather statement should handle this however. The big mashing of teeth comes tonight. The models have continued to back off on precipitation amounts and pushed wrap around precipitation from the low further east. The area in question is the northern Big Horn Basin where snowfall amounts may come in much less than previously thought. However, we kept them up for now. This is mainly due to the combination of snow and strong to possibly high winds. In reality, a high wind warning may have been better for the eastern Big Horn Basin with the ideal northwest flow, tight pressure gradient and cold advection. It could be nasty for a time tonight though, so we kept it up. Further east, northern Johnson county looks to be a better bet with more moisture and a very good chance of strong winds tonight, especially later tonight. Areas further south could also see a period of snow this evening, but should move through quickly and keep amounts fairly light. The main story for Friday will be wind. As the low continues to deepen over the Plains, the pressure gradient will become rather tight. This will mean strong to possibly high winds for some locations. The best chance would be again be in Johnson County and the northern Big Horn Basin. However, many places will likely have windy conditions. And this, combined with colder temperatures will be a slap in the face for many people. Future shifts may want to consider replacing the winter weather advisory with a high wind warning if model trends continue. Some showers will likely continue as well, especially across the east which would be the closest to any wrap around moisture. All precipitation should end relatively quickly in the evening as the low pulls away with dry conditions later at night. Saturday at this point looks largely dry for most areas, although on the cool side. The plus will be MUCH less wind. A weak wave may bring a few showers to the northwest later in the day, but nothing of consequence. .LONG TERM...Sunday through Thursday Ridge continues to build in Sunday before shifting east on Monday. A major warmup occurs Sunday into Monday, especially east of the divide. H7 temps above 0C in all but the far north Sunday and then may be in the +5 to +6C (up to +7 on the new Euro) range Monday. So if this occurs we could see some 70s east of the divide. Widespread 60s again for sure. The warmup is short lived however as the next trough approaches the far west Monday night with a strong cold front sweeping east across the area Monday night into Tuesday morning. Winds will be quite strong out of the s-sw ahead of the front for most of the area Monday with increasing fire concerns where some fuels are drying out (especially if not much snow falls in the east tngt/Fri). Strong to high winds Monday night as the front moves in with winds shift to the west or northwest behind it. General model trend has been stronger and a little slower with this Monday ngt/Tue system as expected. GFS 5- wave is still showing a mean longwave trough developing over the inter-mountain west early next week so this trend may continue. A good shot of snow in the west Monday ngt and Tue with a swath of rain changing to snow along the I80 corridor later Mon ngt into Tuesday. A quick shot of snow in the north is also quite possible Tuesday. Sharply colder and quite windy most areas Tuesday. Shortwave ridge is still expected to move in Wednesday for a dry day. The remnant front may hang in across the far north and east while gusty sw winds develop elsewhere. All the models have another upper low moving towards the 4-corners at the end of this period with another cold front dropping s and se across the area Thursday into Thursday evening. A chance of rain changing to snow, more certain in the mtns will occur in this pattern along with falling temps and gusty n-nw wind. Details on this storm will have to wait another couple days. The active April shows no signs of letting up yet. && .AVIATION...12Z Issuance East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Routes A storm system will be moving through the region today and tonight. Windy conditions will occur at most terminal sites today into this evening. Scattered showers will occur in the north through most of the day. Local MVFR conditions will occur. A cold front moves south through WY this evening with a wind shift to the north and scattered rain and snow showers with local MVFR conditions through 09Z Fri. West of the Divide...KBPI/KJAC/KPNA/KRKS Routes Rain showers and mountain snow showers will occur through mid morning. A cold front will move through western WY around 15Z with rain changing to snow in the lower elevations. MVFR to local IFR conditions will occur through 00Z. Windy conditions will be common at the terminal sites today and tonight. Scattered snow showers will occur tonight in the west. KJAC airport will see MVFR to IFR conditions starting around 09Z the continuing through 12Z Fri. Please see the Aviation Weather Center for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... A cold front will move across the area today. Strong winds are likely for many areas, especially from Rock Springs through Casper. However, with somewhat lower temperatures and higher relative humidity, fire conditions should improve a bit. Snow will fall across much of the west, with some rain and snow showers east of the divide followed by much colder temperatures. Friday at this point looks chilly, windy and showery. Mixing and smoke dispersal will generally range from good to excellent. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Warning from noon today to 9 PM MDT this evening for WYZ019-020-030. Winter Weather Advisory from 9 PM this evening to 6 AM MDT Friday for WYZ013-023. Winter Storm Warning until 6 AM MDT Friday for WYZ001-002-012. Winter Weather Advisory from 9 PM this evening to 3 PM MDT Friday for WYZ010-011. Winter Weather Advisory from 9 PM this evening to 9 AM MDT Friday for WYZ003-004. Winter Weather Advisory until 6 AM MDT Friday for WYZ014-015-024. Winter Weather Advisory until 3 PM MDT Friday for WYZ008-009. && SHORT TERM...Hattings LONG TERM...Skrbac AVIATION...Ross FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 155 AM MDT Thu Apr 12 2018 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- 155 AM MDT Thu Apr 12 2018 ...Winter Storm Warning for northwest Wyoming tonight through Friday morning... ...Assorted Winter Weather Advisories for portions of western, and northern Wyoming... ...High Wind Warnings Thursday afternoon for portions of Fremont, Sweetwater and Natrona Counties... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Snow continuing in the west. Rain will change to snow East of the Divide tonight with a few inches possible. Strong to high winds developing in many areas this afternoon and tonight. Please see warnings, advisories and forecasts for details. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Friday...Strong winds possible across much of the area with snow showers continuing. The worst conditions are expected in Johnson County. Monday and Tuesday...Another strong cold front will blast across Monday night into Tuesday with strong southwest winds ahead of it on Monday and strong northwest winds behind it. Snow will fall out west Monday night and Tuesday with scattered rain changing to snow showers east of the divide later Monday night into Tuesday. Critical fire conditions may occur in Natrona County where fuels have dried out across the lower elevations. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report snow amounts and wind gusts over 50 mph. Team Riverton
Special Weather Statement National Weather Service Riverton WY 138 AM MDT Thu Apr 12 2018 WYZ016>018-122200- Upper Wind River Basin-Wind River Basin-Lander Foothills- Including the cities of Dubois, Riverton, Shoshoni, and Lander 138 AM MDT Thu Apr 12 2018 ...STRONG WIND AND SNOW POSSIBLE THIS AFTERNOON AND EVENING... A cold front will move across the area this afternoon into tonight. Gusty southwest winds will develop ahead of the front, turning northwest in the afternoon. Behind the front, northwest winds of 25 to 35 mph with gusts to 50 mph will be possible for a time. This evening, a period of snow will be possible that could bring a quick inch or two of accumulation. Travelers are urged to watch for strong cross winds this afternoon and slick roads this evening.
The national radar mosaic for the moment the first event began.
1 winter storm, 1 high wind. Local standard time, as filed.
Heavy snow fell in much of the Tetons. The highest amount was 2 feet at the Grand Targhee Ski resort.
Winds were sustained at 40 mph for an hour and a half at Bitter Creek along Interstate 80.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyWarnings in Wyoming, April 2018
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: 748461, 748462.