A Pacific system brought about 6 to 10 inches of snow to parts of the Upper Snake River Plain and Upper Snake River Highlands. Fall River Electric reported thousands of power outages on March 20th.
Every event with a place to put it; 3 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 PIH wrote it up.
A Pacific system brought about 6 to 10 inches of snow to parts of the Upper Snake River Plain and Upper Snake River Highlands. Fall River Electric reported thousands of power outages on March 20th.
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 Pocatello, ID wrote its last area forecast discussion before the first event at Mar 19, 12:39 PM MST, 5 hours 21 minutes earlier.
Area Forecast Discussion National Weather Service Pocatello ID 139 PM MDT Fri Mar 19 2021 .SHORT TERM...Tonight through Sunday night. Early afternoon satellite imagery was showing a low pressure system advancing into the NW coast as associated downstream showers and thunderstorms advanced east across SW Idaho into the CNTRL mountains and portions of the Snake River Plain. Two of the Hires numerical models suggest that some of this convection may spread into the Shoshone/Sun Valley area later this afternoon while the entire band of precipitation intensifies this evening and spreads slowly east through the Snake Plain tonight and into the ERN mountains eventually exiting south and east of the area sometime around noon on Saturday. In the wake of this moderate to heavy band of precipitation, rainfall intensities look to run up towards Debris Flow criteria across the Badger Fire Burns Scar. The necessary hourly intensities appear to fall short of the minimum threshold set for a debris flow and thus we have issued an Areal Flood Advisory for that region tonight which could be upgraded to a Flash Flood/Debris Flow warning if necessary. Additionally, snow totals across the ERN mountains late tonight through Saturday morning are expected to exceed the minimum threshold for a Winter Weather Advisory and thus we will post highlights for that region with impacts mainly expected across higher elevations and mountain passes. The main trough migrates slowly through the region Saturday resulting in scattered to numerous snow showers favoring the mountains. The trough axis clears the region by Sunday morning with both operational models not really showing the associated convergence that they had yesterday. We will hold on to some mention of snow showers overnight and adjust as needed if the models come back to the convergence scenario. Sunday looks relatively dry per the NAM while the GFS continues to show some upslope NW flow snow showers over the CNTRL and ERN mountains throughout the day. The leading edge of the next storm system spills into the region late Sunday night with NW upslope flow favoring enhanced precipitation chances across the CNTRL and ERN mountains heading into Monday morning. Breezy conditions were noted across the Arco Desert this afternoon and near Advisory level wind speeds are expected across the Magic Valley and CNTRL Snake River Plain Saturday. The models have not been very consistent with either the timing nor the placement of the stronger winds so will hold off on issuing any special statements for wind at this time. Got enough on my plate as you might imagine. Temperatures should run at or below climatological norms over the next couple of days. Huston .LONG TERM...Monday through next Friday. Continued shortwaves expected to move through our area next week which would allow for continued snow showers Monday into Tuesday. Most of these showers are expected in mountainous terrain, with 2 to 7 inches forecast as an average. Some cooler morning temperature are in store Tuesday and Wednesday mornings, into the 20s or even teens for some Wednesday morning. High pressure looks to build in from the west Wednesday which would dry out our area briefly. Fairly active conditions continue the latter half of the week which bring in another round of rain and snow showers to our area. At this time Friday looks to be a fairly dry day with high pressure building in from the west once again. ND && .AVIATION...Several challenges in the forecast tonight and into tomorrow morning. This will include the precipitation type that is forecast to fall and its impact to visibility in particular. We are generally expecting precipitation to begin to fall as rain this evening, with a mention of thunder in the vicinity of some sites. TS may even appear on station. We are expecting a transition from rain to snow at most sites. The general timing of when this will happen is forecast after midnight and between 3am, however the timing of exactly when this will happen may vary a few hours. Meanwhile, as the frontal boundary responsible for this transition passes through our area, expect a brief increase in wind speeds as well as a shift in wind direction. This shift, from a southerly wind, to a west/northwest wind, is forecast this evening. Wind gusts to 30 kts are possible. Ceiling heights are expected to reduce with the passage of the frontal boundary as well, generally expected at MVFR category. Ceilings may drop to IFR but at this point we are hinting at that with scattered groups. ND && .HYDROLOGY...Have issued an Areal Flood Advisory to cover the Badger Fire Burn Scar tonight. You can read all about the details in the Short Term section above. Huston .PIH WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight through 2PM MDT Saturday for IDZ060-062>064-066. &&
The national radar mosaic for the moment the first event began.
3 heavy snow. Local standard time, as filed.
Eight inches of heavy, wet snow fell in Ashton and Fall River Rural Electric reported thousands of customers with power outages on March 20th due to the snow weight.
The Island Park COOP observer recorded 9.4 inches of snow. 5 inches fell in Marysville. Fall River Rural Electric reported thousands of customers in Fremont County without power on March 20th due to the heavy snow on power lines. The White Elephant and Island Park SNOTEL sites recorded an estimated 8 inches.
Six inches of snow fell in Sugar City and 6 inches fell in Saint Anthony. 2 inches fell in Idaho Falls. The very heavy and wet snow caused power outages to nearly 2,000 customers in the Idaho Falls area on March 20th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2021Every state in 2021This day in weather historyWarnings in Idaho, March 2021
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: 951220, 951221, 951222.