A series of upper level disturbance brought very heavy snow to localized areas of western Wyoming. Across portions of the Tetons, persistent convective banding set up and brought periods of 2 to 3 inch an hour snowfall.
Every event with a place to put it; 4 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 series of upper level disturbance brought very heavy snow to localized areas of western Wyoming. Across portions of the Tetons, persistent convective banding set up and brought periods of 2 to 3 inch an hour snowfall. At the Grand Targhee Ski Resort, 57 inches of snow was recorded through the storm. Jackson Hole received 29 inches of new snow. Heavy snow fell in the Jackson Valley as well with 8 to 14 inches around the valley. Lincoln County also saw heavy snow with over 1 foot common in the Star Valley with a maximum of 19 inches near Thayne.
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 2, 10:45 AM MST, 15 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1045 AM MST Fri Mar 2 2018 .SHORT TERM...Friday through Sunday night Looks like we have another active period coming up. And with the differences in the weather at times, we will split the discussion into West and East of the Divide. West of the Divide...Things are mainly quiet out there right now. However, this will change as a cold front and associated upper level disturbance cross the area today and bring some snow. At this point, the heaviest snow looks to be this afternoon when the area gets into some left front jet quadrant dynamics. However, the system is a fairly quick hitter. So at this point, the winter weather advisories look good and we will leave them as is. There should then be a break as the area will be in between systems from late tonight through most of Saturday. There will still be some light snow from time to time but nothing to write home about. Temperatures will cool a bit, but with the Pacific origin of the air, nothing unusual for the first part of March. The next shot of snow looks to move in for Saturday night and into Sunday morning. There is a but more uncertainty with this system though. The snow looks a bit more convective and banded. And as a result, this is very difficult to nail down exactly where the heaviest snow to fall, especially this far out. So as a result, we made few changes to QPF or snowfall amounts until things become a little clearer. The snow here should end by late Monday night as the system moves away to the east and high pressure builds into the area. East of the Divide...For today, the concern switches to wind. With the models showing 55 to 60 knots of southwest flow at 700 millibars across the southwestern Wind Corridor, we upgraded the high wind watch to a warning for today. Many areas will have breezy conditions as well. With the increased mixing, temperatures should warm in many areas today, with 40s looking likely in many locations. As for precipitation, with the strong downsloping flow, it looks rather unlikely. Mainly dry weather looks to hold through Saturday morning. The next wave will begin to move into the north Saturday afternoon. The models are trending a bit slower though, so it would not surprise me if most areas were dry through the day Saturday. Snow then spreads across the area Saturday night into Sunday. As was previously stated, the models continue to come in slower so we lowered POPS at night as many areas in the east could remain dry through that period. Most areas will see some on Sunday. And like out west, the problem is that it looks convective and banded. And like out west, the models have poor agreement in where they will set up and when. So for now, we continued the broad brush of the amounts until more details can be included. At this time, it looks like advisory level amounts with locally higher amounts where that elusive banding decides to get up. .LONG TERM...Monday through Friday A relatively quiet long term is expected in wake of the winter storm impacting the area in the short term. A trailing shortwave on Monday, and perhaps some lingering wrap-around moisture from the departing storm could give the northwest and northern mountains and perhaps adjacent foothills some additional light snow. A weak shortwave in the northwest flow is expected to push southeast across the area Tuesday, but will have little available moisture to work with. Thus will keep the ongoing dry forecast as is. Some ridging is then expected Wednesday with continued dry conditions. Models show the ridge flattening out Wednesday night/Thursday with the potential for a moist westerly flow developing Thursday followed by shortwave trough in the flow pulling across the northern Rockies Friday. For now will only go slight chance PoPs across the west Thursday/Friday with a slight emphasis on Friday. Temperatures are expected to be below average Monday and Tuesday with seasonal temperatures by Wednesday or Thursday. && .AVIATION...18Z Issuance West of the Continental Divide...KJAC, KBPI, KPNA, and KRKS Broad low pressure system over the western US is now impacting western Wyoming. KJAC to see the most impact over the next 24 hours with MVFR to IFR conditions expected with continuous snow and snow showers, as mid-level SW flow bring steady moisture into the area. Winds to gust 25 kts this afternoon. KBPI/KPNA should remain VFR/MVFR through the period with intermittent snow showers. Precipitation and lowering ceiling not expected to impact KRKS until 12-18Z/Sun. Mountains to be obscured through the period. LLWS to also be an issue at times and wind speeds/turbulence to be an issue around the mountains and gaps. East of the Continental Divide...KCPR, KCOD, KRIW, KLND, and KWRL VFR conditions expected for the next 24 hours east of the divide as strong southerly flow is pushed ahead of the low pressure system to the west. LLWS to be the primary impact at terminals through the period, with gusts 30 to 40 kts possible at some locations, especially KCPR. Wind shift from the north to push into the Big Horn Basin (KCOD/KWRL) after 15Z/Sat. Primary storm impact of snow with reduced ceilings and visibilities to not move east of the divide until after 12Z/Sun. && .FIRE WEATHER... Periods of snow will spread back into the west today as an upper level disturbance and front approach the area. Meanwhile, expect dry weather East of the Divide with warmer temperatures for most areas. Expect breezy conditions for many areas with strong to high winds from the Red Desert through Natrona County. The next chance of snow East of the Divide should hold off until Saturday night. Mixing and smoke dispersal will range from poor in the deeper valleys to good to very good in the windier locations. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 8 AM this morning to 11 PM MST this evening for WYZ001-012>015-023-024. High Wind Warning from 8 AM this morning to 5 PM MST this afternoon for WYZ019-020. && SHORT TERM...Hattings LONG TERM...Murrell AVIATION...McDonald FIRE WEATHER...Hattings
Hazardous Weather Outlook National Weather Service Riverton WY 202 AM MST Fri Mar 2 2018 WYZ001>020-022>030-031200- 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- 202 AM MST Fri Mar 2 2018 ...Winter Weather Advisory in effect for western Wyoming today into this evening... ...High Wind Warning today for portions of Fremont and Natrona Counties... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Periods of snow in the west. Please see Winter Weather products for details. High winds are likely today from the Red Desert through Natrona County. Please see High Wind Warning for details. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Saturday into Sunday...Periods of snow in the west, spreading East of the Divide Saturday night and especially into Sunday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report snowfall amounts and wind gusts past 50 mph. Thank you. TEAM RIVERTON
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 Yellowstone Park. Some of the higher amounts included 15 inches at Two Oceans Plateau and 14 inches at Lewis Lake Divide.
Persistent convective banding set up over Teton County and brought heavy snow to some areas, especially on western facing slopes. Grand Targhee received copious amounts of snow with 57 inches at Chief Joseph and 41 inches at the SNOTEL site. The Jackson Hole ski resort received 29 inches of snow. Many other locations had over a foot of new snow.
Heavy snow fall in portions of the Star Valley. Snowfall amounts ranged from 9 inches near Smoot to 19 inches near Thayne.
A long lived snow event brought heavy amounts to much of the Jackson Valley. Some amounts included 8 inches at Moose and 13.2 inches at Jackson Dam.
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: 739837, 739839, 739841, 739840.