A very large and very cold arctic air mass from the Canadian Rockies, swept south and east over our entire region. With enough clearing skies, even light winds resulted in wind chill values lower than 40 below zero for many northeast Montana locations.
Every event with a place to put it; 5 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 very large and very cold arctic air mass from the Canadian Rockies, swept south and east over our entire region. With enough clearing skies, even light winds resulted in wind chill values lower than 40 below zero for many northeast Montana locations.
The national radar mosaic for the moment the first event began.
5 cold/wind chill. Local standard time, as filed.
At the Malta mesonet site, on the southern edge of Malta (A3570), temperatures of -21 to -27 combined with wind speeds of 6 to 8 mph to create wind chill values of -40 to -44 for a 15 hour period from the night of the 14th through the morning of the 15th.
At the Glentana mesonet site (F2113), temperatures of -20 to -23 combined with wind speeds of 6 to 12 mph to create wind chill values of -40 to -41 for a period of 2 hours and 45 minutes during the morning of the 15th. In addition, at the Bluff Creek RAWS site (BLUM8), temperatures of -23 to -26 combined with wind speeds of 6 to 9 mph to create wind chill values of -41 to -43 for about 5 hours from the night of the 14th into the early morning of the 15th.
At the Navajo MT-5 DOT site (MTRED), temperatures of -18 to -22, combined with wind speeds of 7 to 15 mph, to create wind chill values of -40 to -43 during the early morning hours and late morning hours of the 15th.
At the Comertown Turn-Off MT-5 DOT site (MTCOM), temperatures of -17 to -23, combined with wind speeds of 7 to 22 mph, to create wind chill values of -40 to -45 on the 15th during the early morning hours, followed by a pause, then again from late morning through early afternoon.
At the USCRN at Poplar River site (PRSM8), 29 ENE Wolf Point, temperatures of -26 to -28 combined with wind speeds of 4 to 5 mph to create wind chill values of -40 to -42 for a period of 3 hours during the early morning of the 15th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2020Every state in 2020This day in weather historyWarnings in Montana, January 2020
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 2026-10-01. Each event’s entry at NCEI: 873370, 873368, 873712, 875302, 873369.