Montana, 2021Heavy Snow and High Wind in Montana, April 18 to 19, 2021
April 18 to 19, 2021 · NWS MSO · 6 events in 6 counties and zones
A Canadian cold front moved across the Continental Divide into western Montana during the afternoon and evening hours of April 18th. Temperatures quickly fell behind the front, with strong winds leading to power outages across portions of northwest Montana.
Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
Open the live radar over this ground
- Deaths
- 0
- Injuries
- 0
- Property damage
- $80,000
- Crop damage
- None recorded
- Events
- 6
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.
A Canadian cold front moved across the Continental Divide into western Montana during the afternoon and evening hours of April 18th. Temperatures quickly fell behind the front, with strong winds leading to power outages across portions of northwest Montana. A band of heavy snow impacted southern portions of the Bitterroot Valley during the morning of April 19th.
What forecasters said that day
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 Missoula, MT wrote its last area forecast discussion before the first event at Apr 18, 1:09 PM MST, 2 hours 51 minutes earlier.
Area forecast discussion, Apr 18, 1:09 PM MST, 2 hours 51 minutes before
Area Forecast Discussion
National Weather Service Missoula MT
209 PM MDT Sun Apr 18 2021
.DISCUSSION...
A vigorous cold front will move south across the Northern Rockies
this afternoon and evening, bringing a blast of cold air and high-
elevation snow across the Continental Divide. Boaters on Flathead
Lake this afternoon and evening will find conditions a bit
inhospitable due to a sudden shift to northerly winds and increased
wave activity. Area travel will be impacted by snow, blowing snow,
and low visibility across southwest Montana and over mountain passes
(particularly passes along the Continental Divide, such as Marias,
MacDonald, and Homestake, where 1-inch per hour snow could develop
for a time). For high-elevation southwest Montana valleys above 4500
feet, there will be a mix of snow accumulating, melting, and icing
up on roadways. Travel conditions may be drastically different among
locales. The snow will quickly subside by mid morning on Monday,
with a relatively cold and brisk remainder of the day throughout
much of the region.
Weak high pressure will develop across the Northern Rockies Monday
through Wednesday, with temperatures gradually moderating to near
the seasonal average.
Thursday through Friday, another storm system is anticipated to
sweep south across the Northern Rockies, bringing another
opportunity for at least brief snow impacts across the Continental
Divide Thursday overnight. Models and their ensembles have trended
toward depicting an increasingly dynamic storm system during this
time, however clarity in specific timing is lacking at the moment.
High pressure is expected to return to the Northern Rockies Friday
to Saturday, rapidly warming and drying the region. The larger scale
pattern appears to transition from northerly flow to westerly flow
over the weekend, with a series of Pacific storm systems set to move
across the region during much of the following week. Thunderstorms
may become a bigger part of the forecast picture by Sunday
afternoon, as southwest flow aloft intensifies and the atmosphere
destabilizes.
&&
.AVIATION...A Canadian cold front has already increased winds out
of the N-NE at KGPI as of 19/20Z, with gusts up to 33 knots
observed. These kinds of winds will occur at all area terminals
throughout the afternoon and evening as the front makes its way
across the region. Precipitation will begin to increase at KGPI by
19/00Z or around there, beginning as a rain but transitioning to
a rain/snow mix through Monday, 19/15Z. KMSO, KBTM, and KSMN will
also experience similar precipitation trends shortly thereafter,
and will continue through roughly 19/18Z. Winds and precip will
diminish after 19/18Z.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 6 PM this evening to noon MDT
Monday Butte/Blackfoot Region.
Wind Advisory until midnight MDT tonight for Flathead Lake in
the Flathead/Mission Valleys.
ID...None.
&&Event by event
2 winter weather, 2 strong wind, 1 high wind, 1 heavy snow. Local standard time, as filed.
Winter Weather, West Glacier Region
- When
- April 18, 4:00 PM MST to April 19, 2:00 AM MST
- Where
- West Glacier Region forecast zone
- Reported by
- Department of Highways
- Coordinates
- 47.971, -114.069 (the zone’s center; the record gives no point)
Winter driving conditions were observed on US Highway 2 from Essex to Marias Pass due to the combination of gusty northeast winds and moderate to heavy snowfall. Montana Department of Transportation officials reported 3 inches of snow on roadways at Devil Creek. An estimated 7-9 inches of snow fell at Marias Pass.
Strong Wind, Kootenai/Cabinet Region
- When
- April 18, 4:30 PM MST to 6:00 PM MST
- Where
- Kootenai/Cabinet Region forecast zone
- Measured
- 43 kt (49 mph) estimated gust
- Property damage
- $75,000
- Reported by
- Utility Company
- Coordinates
- 48.171, -114.863 (the zone’s center; the record gives no point)
Strong winds behind a fast moving cold front led to several downed trees and numerous power outages in the vicinity of Troy, Bull Lake, and in the Yaak. The Northern Lights COOP reported more than 2400 customers without power from north of Bonners Ferry to the Canadian border and into northwest Montana through Troy, Bull Lake, and the Yaak.
Strong Wind, Flathead/Mission Valleys
- When
- April 18, 5:00 PM MST to 6:30 PM MST
- Where
- Flathead/Mission Valleys forecast zone
- Measured
- 42 kt (48 mph) measured gust
- Property damage
- $5,000
- Reported by
- Utility Company
- Coordinates
- 47.872, -114.424 (the zone’s center; the record gives no point)
Strong northeast winds led to power outages on the East Lakeshore of Whitefish Lake, in Bigfork, and at Lake Blaine. Two trees were snapped in half in the Lake Blaine area.
High Wind, Lower Clark Fork Region
- When
- April 18, 5:30 PM MST to 10:00 PM MST
- Where
- Lower Clark Fork Region forecast zone
- Measured
- 50 kt (58 mph) measured gust
- Reported by
- Law Enforcement
- Coordinates
- 47.286, -114.685 (the zone’s center; the record gives no point)
Sanders County Dispatch reported numerous trees and power lines down along Highway 200 between Thompson Falls and Trout Creek. Trees fell across power lines in five areas along Blue Side Road between Thompson Falls and Trout Creek, igniting a few small wildfires. Power outages were also observed in the Heron area from fallen trees.
Winter Weather, Bitterroot / Sapphire Mountains
- When
- April 18, 10:00 PM MST to April 19, 5:00 AM MST
- Where
- Bitterroot / Sapphire Mountains forecast zone
- Reported by
- Mesonet
- Coordinates
- 46.508, -113.828 (the zone’s center; the record gives no point)
A period of moderate snow impacted travel across Lolo Pass on US Highway 12 and across Lost Trail Pass on US Highway 93 from the evening hours of April 18 to the morning hours of April 19. New snow of 3-4 inches was reported by area SNOTEL sites.
Heavy Snow, Missoula / Bitterroot Valleys
- When
- April 19, 12:00 AM MST to 8:00 AM MST
- Where
- Missoula / Bitterroot Valleys forecast zone
- Reported by
- Public
- Coordinates
- 46.560, -114.023 (the zone’s center; the record gives no point)
A band of heavy snow set up across southern portions of the Bitterroot Valley during the morning hours of April 19 following the passage of a Canadian cold front. The spring snow led to school delays and closures, with Corvallis cancelling school. Snow was measured at 5-9 inches during this event.
- Winter Weather
- Snow, sleet or freezing rain below warning levels that still caused disruption, damage or casualties.
- Strong Wind
- Non-thunderstorm winds below high wind criteria that nonetheless caused damage or casualties.
- High Wind
- Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
- Heavy Snow
- Snowfall reaching the local warning threshold without the other hazards of a winter storm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
- Rip Current in North Carolina, April 18, 20211 death · 1 event
- Damaging Wind in Florida, April 18, 2021$2.5 million · 50 kt wind · 1 event
- Strong Wind in Idaho, April 18, 2021$80,000 · 3 events
- Wildfire and Dust Storm in Washington, April 18 to 19, 2021$45,000 · 60 kt wind · 5 events
- Heavy Snow and Winter Weather in Montana, April 18 to 19, 202114 events
- Winter Storm and Winter Weather in South Dakota, April 18 to 19, 202113 events
- Tornado and Hail in Florida, April 18, 2021EF0 · 6 events
- Winter Storm in Montana, April 18 to 19, 20216 events
- Marine Hail in South Atlantic Coastal Waters, April 18, 20211.5 in hail · 3 events
- Hail in Texas, April 18, 20210.88 in hail · 2 events
- Winter Storm in Wyoming, April 18 to 19, 20212 events
- Marine Thunderstorm Winds in Gulf of Mexico, April 18, 20212 events
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: 948193, 948194, 948264, 948266, 948192, 948191.