A slow moving area of low pressure moved through Wyoming and brought locally heavy snow to portions of central Wyoming. The heaviest snow fell in portions of Fremont and Johnson Counties.
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The episode as NWS RIW wrote it up.
A slow moving area of low pressure moved through Wyoming and brought locally heavy snow to portions of central Wyoming. The heaviest snow fell in portions of Fremont and Johnson Counties. Around Riverton there were widespread reports of 6 to 9 inches of snow with 6 to 8 inches in the vicinity of both Buffalo and Kaycee in Johnson Counties.
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 25, 5:14 PM MST, 46 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 614 PM MDT Sun Mar 25 2018 .UPDATE... Issued at 609 PM MDT Sun Mar 25 2018 Added Winter Weather Advisories to the southeast portion of the Bighorn Basin which will be on the north end of heavier precipitation band expected to set up over central Wyoming tonight. && .SHORT TERM...This evening through Wednesday Issued at 211 PM MDT Sun Mar 25 2018 The main Pacific low pressure trough remains west along the western border of Idaho extending south into northern Nevada. Colder and drier air continues to move through the through limiting moisture in the southwest flow over western Wyoming. Minimal instability making snowfall somewhat showery. Surface low already developed in eastern Colorado with northeast low level flow under the southwest flow aloft. Snow steady in north central over Bighorn mountains and northern Johnson county. Updated to start warning up there earlier, around 940 am mdt with 1 to 3 inch morning snow reports vicinity Buffalo. Rest of warnings and advisories on track. Question about when main impact ends on Monday and may be able to drop highlights about noon as temperatures support mainly rain to rain snow mix with little or no accumulation of snow in the afternoon. Have left as is for now. In the western mountains light snow accumulations expected tonight and Monday with partial clearing Monday night and Tuesday with lingering light snow showers as a high pressure ridge builds in over the area. East some snow will linger Monday evening but upper support and moisture moves east rapidly. Threat of fog after midnight and Tuesday morning over fresh snow cover. Wednesday southwest flow returns bringing some Pacific moisture into thew northwest mountains with light snowfall increasing. Most areas will be warming Tuesday night and Wednesday. .LONG TERM...Wednesday night through Sunday night Issued at 211 PM MDT Sun Mar 25 2018 The region continues to be dominated by NW flow through the period. Rain (east of the Divide) and snow showers will be ongoing Wednesday night into Thursday. This activity will become confined to the northern and western mountains Thursday night. Remnants of the ridge that was positioned over the EPAC on Thursday could transition over the Northern/Central Rockies Thursday night into Friday, which could dry conditions out even more. A second system/cold front will impact the area from the north during the day on Saturday, once again bringing widespread precip chances to the forecast area. At this time, the cold air associated with this system will stay over areas east of the Divide. && .AVIATION...For the 00Z TAFS through 00Z Tuesday Issued at 211 PM MDT Sun Mar 25 2018 West of the Divide...KBPI/KJAC/KPNA/KRKS Routes Bands of snow showers and mountain obscurations will continue, vicinity and north of a vicinity KEVW- KPNA line and continue through early Monday morning. Convective showers will move along the cold front this evening and impact KRKS this evening and linger through 12Z Monday. Conditions will begin to improve across the area after 12Z Monday, with VFR conditions expected across the area by 18Z. Gusty WNW winds will develop by this time for all terminals, except KJAC. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Routes Scattered MVFR, isolated IFR snow showers will continue over the Bighorns and Johnson County today. Precipitation is expected to start as rain late this afternoon into this evening, as temperatures remain well above freezing. Snow showers are expected to become more numerous and push southward this evening with more widespread MVFR, areas of IFR conditions, expected vicinity and north of a KLND-KCPR line after 03z Monday. This activity will begin to end from north to south after 06Z Monday, impacting KCOD and reaching KWRL by 15Z. VCSH is expected at the remaining terminals, with MVFR ceilings, after 18Z Monday. && .FIRE WEATHER... Issued AT 211 PM MDT Sun Mar 25 2018 The main Pacific low pressure trough remains west along the western border of Idaho extending south into northern Nevada. Colder and drier air continues to move through the through limiting moisture in the southwest flow over western Wyoming. Minimal instability making snowfall somewhat showery. Surface low already developed in eastern Colorado with northeast low level flow under the southwest flow aloft. Snow steady in north central over Bighorn mountains and northern Johnson county. Updated to start warning up there earlier, around 940 am mdt with 1 to 3 inch morning snow reports vicinity Buffalo. Rest of warnings and advisories on track. Question about when main impact ends on Monday and may be able to drop highlights about noon as temperatures support mainly rain to rain snow mix with little or no accumulation of snow in the afternoon. Have left as is for now. In the western mountains light snow accumulations expected tonight and Monday with partial clearing Monday night and Tuesday with lingering light snow showers as a high pressure ridge builds in over the area. East some snow will linger Monday evening but upper support and moisture moves east rapidly. Threat of fog After midnight and Tuesday morning over fresh snow cover. Wednesday southwest flow returns bringing some Pacific moisture into thew northwest mountains with light snowfall increasing. Most areas will be warming Tuesday night and Wednesday. Most areas will have poor smoke dispersal with low clouds and precipitation on Monday. The south and west may mix enough with sunshine on Tuesday for at least low end good smoke dispersal while east and north will have a low level inversion over colder air and poor smoke dispersal will result on Tuesday. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon MDT Monday for WYZ005>007. Winter Weather Advisory until noon MDT Monday for WYZ017>020. Winter Weather Advisory until 6 PM MDT Monday for WYZ008-009-015. Winter Storm Warning until 6 PM MDT Monday for WYZ010-011. && UPDATE...Meunier SHORT TERM...Baker LONG TERM...LaVoie AVIATION...LaVoie FIRE WEATHER...Baker
Hazardous Weather Outlook National Weather Service Riverton WY 619 PM MDT Sun Mar 25 2018 WYZ001>020-022>030-261100- 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- 619 PM MDT Sun Mar 25 2018 ...Winter Storm Warning for eastern Johnson County tonight and Monday... ...Winter Weather Advisories for portions of central Wyoming and the Bighorn mountains tonight and Monday... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Areas of moderate to locally heavy snow are expected to develop across the Wind River Basin, Southeast Bighorn Basin, northern Natrona County and Johnson County by midnight. Please see Winter Storm Warnings and Winter Weather Advisories for the latest information. .DAYS TWO THROUGH SEVEN...Monday through Saturday Monday...Snow will become light across most of central Wyoming after sunrise, and then gradually taper off from west to east through the afternoon. Wednesday and Thursday...A chance of rain and snow showers with snow in the mountains. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report snow amounts.
The national radar mosaic for the moment the first event began.
4 winter storm. Local standard time, as filed.
Heavy snow fell in portions of the Wind River Basin. Around Riverton, 7 to 9 inches of snow fell with around 8 inches in Hudson.
Around the Lander Foothills, 6 to 8 inches of snow fell, including at the Lander airport.
Heavy snow fell in portions of northern Johnson County. The highest amount recorded was 7 inches 13 miles east-southeast of Buffalo.
Heavy snow fell in portions of southern Johnson County. The highest amounts measured was 9 inches, 17 miles to the northwest of Kaycee.
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, March 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: 742224, 742225, 742222, 742223.