A few helpful snow and rain showers brought a little relief to some areas through the month, but were not enough to weaken the drought's hold across the region. Overall, precipitation amounts remained below normal.
Every event with a place to put it; 15 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 GGW wrote it up.
A few helpful snow and rain showers brought a little relief to some areas through the month, but were not enough to weaken the drought's hold across the region. Overall, precipitation amounts remained below normal.
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 Glasgow, MT wrote its last area forecast discussion before the first event at Apr 30, 12:08 PM MST, 11 hours 52 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 108 PM MDT Fri Apr 30 2021 .DISCUSSION... Chinook arch clouds disipated by mid afternoon and the warm and very dry conditions ensued across the area. Min Relative Humidities in the single digits are rare for this part of the world and are possible within 75 miles of the Dry Arm of Fort Peck Lake this afternoon. NW flow will increase overnight with an increase in 700 & 850 mb winds. Some gusts over 30 mph are possible over Fort Peck Lake, so extended the Lake Wind Advisory through Saturday. Otherwise, the weekend will be cooling down with more winds into Sunday. Winds will quiet down next week while temperatures hover near normal as a broad upper trough moves through. There may be a few isolated showers moving across the area Tuesday and Wednesday, but nothing more till they move to our east. A ridge then builds in over the area late in the week before a stronger system moves in from the Pacific NW. This system looks to give the area a better chance of measureable rain, so we'll have to keep our fingers crossed this works out. TFJ && .AVIATION... VFR. Look for winds to diminish early this evening but Wind Shear will be a problem overnight as winds a couple thousand feet AGL will remain strong (about 40 kts). Another breezy day expected Saturday although wind speeds not expected to be as high as today. && .FIRE WEATHER... Winds are expected to diminsh somewhat tonight but they will remain strong just a couple thousand feet above the ground that may bring periodic gusts overnight. Humidities will also stay low overnight south of the Missouri River, especially from Jordan to Glendive, so extended the Red Flag warning till 3 am tonight for this area. Higher humidities are expected tomorrow and doesn't look like critical fire weather conditions are a sure bet so will leave going Fire Weather Watch alone and let the night shift get another look at it. && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 3 AM MDT Saturday for MTZ122-137. Red Flag Warning until 9 PM MDT this evening for MTZ120-134>136. Fire Weather Watch from Saturday afternoon through Saturday evening for MTZ120-122-134-136. Lake Wind Advisory until 6 PM MDT Saturday For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && weather.gov/glasgow
The national radar mosaic for the moment the first event began.
15 drought. Local standard time, as filed.
Ongoing drought conditions (D3-Extreme) continued across all of Sheridan County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across all of Eastern Roosevelt County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across all of Richland County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across all of Dawson County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across all of Wibaux County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across all of Northern Valley County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across most of Prairie County and in the first week of May, extended a bit further into the northwest corner of the county. D2-Severe drought held on to the southwest portion of the county.
Ongoing drought conditions (D3-Extreme) continued across all of Western Roosevelt County through the entire month of May.
Ongoing drought conditions (D3-Extreme) continued across most of Central and Southern Valley County and in the first week of May, extended a bit further toward the southwest, while D2-Severe drought conditions held on to the far southwestern portion of Central and Southern Valley County.
To start the month of May, ongoing drought conditions (D3-Extreme) from the eastern half of McCone County spread westward across most of the rest of the county, leaving only a small sliver of D2-Severe drought in southwestern McCone County.
Ongoing drought conditions (D2-Severe) across all but the southeastern edge of Garfield County worsened, in the first week of May, to include (D3-Extreme) drought in the far northeastern corner of the county (Haxby Point).
To start the month of May, D3-Extreme drought conditions persisted in the far northeastern portion of Central and Southeastern Phillips County and D2-Severe drought conditions now covered the remainder of Central and Southeastern Phillips County.
Ongoing drought conditions (D2-Severe) in the western third of Northern Phillips County, and D3-Extreme drought in the eastern two thirds of Northern Phillips County continued through the entire month of May.
Ongoing drought conditions (D2-Severe) for all but the southwestern corner of Petroleum expanded to cover all of the county in the first week of May.
Ongoing drought Conditions (D3-Extreme) continued across all of Daniels County through the entire month of May.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, May 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: 952286, 952287, 952288, 952289, 952291, 952292, 952897, 952902, 952903, 952905, 952906, 952907, 952910, 952911, 952914.