A very cold arctic air mass moved south out of Canada. Associated with the leading edge of the cold air were strong winds, producing bitterly cold wind chill temperatures.
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 MSO wrote it up.
A very cold arctic air mass moved south out of Canada. Associated with the leading edge of the cold air were strong winds, producing bitterly cold wind chill temperatures.
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 Dec 30, 2:45 PM MST, 1 hour 49 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 245 PM MST THU DEC 30 2010 ...VERY COLD TEMPERATURES ACROSS WESTERN MONTANA AND NORTH CENTRAL IDAHO FOR TONIGHT AND FRIDAY NIGHT... .DISCUSSION... LATE THIS AFTERNOON THROUGH SATURDAY...EAST AND NORTHEASTERLY WINDS ACROSS WESTERN MONTANA WILL SLOWLY DIMINISH DURING THE REMAINDER OF TODAY...WITH THE WINDCHILL IMPACT DIMINISHING AS WELL. ARCTIC AIR WILL SETTLE ACROSS VALLEY LOCATIONS OVERNIGHT...WITH SCATTERED TO BROKEN MID LEVEL CLOUD COVER ALLOWING TEMPERATURES TO PLUMMET. MANY VALLEY LOCATIONS NEAR THE CONTINENTAL DIVIDE MAY EXPERIENCE TEMPERATURES AS LOW AS MINUS 30 DEGREES BY FRIDAY MORNING. LIGHT NORTHERLY FLOW AND A RELATIVELY WARM FLATHEAD LAKE...SOME LAKE EFFECT FLURRIES AND LIGHT SNOW ARE POSSIBLE ALONG THE SOUTHERN SHORE OF THE LAKE...INCLUDING POLSON DURING THE OVERNIGHT TONIGHT. CONSIDERING THAT HIGH PRESSURE WILL BE PRESENT OVER THE NORTHERN ROCKIES ON FRIDAY...TEMPERATURES WILL STRUGGLE TO REACH THE SINGLE DIGITS ABOVE ZERO DURING FRIDAY AFTERNOON. FRIDAY NIGHT THROUGH SATURDAY MORNING WILL ALSO BE VERY COLD FOR WESTERN MONTANA...WHILE IT WILL LIKELY THE COLDEST PERIOD FOR NORTH CENTRAL IDAHO DURING THE NEAR TERM. SATURDAY AFTERNOON TEMPERATURES ARE EXPECTED TO WARM SLIGHTLY OVER THOSE ON FRIDAY. SATURDAY NIGHT THERE WILL BE A NORTHWEST FLOW OVER WESTERN MONTANA AND NORTH CENTRAL IDAHO. A DISTURBANCE WILL MOVE ACROSS CENTRAL MONTANA SUNDAY AFTERNOON AND NIGHT WHICH COULD BRING A FEW SHOWERS TO WESTERN MONTANA...ESPECIALLY TO NORTHWEST MONTANA AND ALONG THE CONTINENTAL DIVIDE. MONDAY AND TUESDAY WILL SEE A WEAK RIDGE OF HIGH PRESSURE MOVE OVER IDAHO...BRINGING LESS CLOUDS AND DECREASING CHANCE OF PRECIPITATION. BY THURSDAY ANOTHER PACIFIC WEATHER SYSTEM WILL BE MOVING TOWARD WESTERN MONTANA...AND SPREADING SOME SNOW IN FROM THE WEST. && .AVIATION...FLYING CONDITIONS WILL IMPROVE DURING THE NEXT 24 HOURS...AS THE PREVIOUS STORM SYSTEM MOVES EAST OF THE NORTHERN ROCKIES. SNOW WILL BE MOSTLY TERRAIN BASED AND SLOWLY DIMINISH THROUGHOUT THE REMAINDER OF TODAY. MUCH OF THE VISIBILITY AND LOW CEILINGS CONCERNS WILL BE DUE TO SNOW AND MOST CONCENTRATED ALONG THE CONTINENTAL DIVIDE. THE AMOUNT OBSCURED TERRAIN WILL DECREASE DURING THIS TIME ALSO. NORTHEASTERLY WINDS AT KGPI WILL REMAIN FAIRLY CONSTANT THROUGH THIS EVENING AND DIMINISH SIGNIFICANTLY AFTER SUNSET. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && SHORT TERM...ZUMPFE LONG TERM....KOLATA AVIATION...ZUMPFE
The national radar mosaic for the moment the first event began.
3 extreme cold/wind chill. Local standard time, as filed.
Wind chill temperatures dropped to -21 F at 4:34pm MST and remained below -20 through 8:49pm MST, at Gilmore Idaho.
The wind chill temperature fell below -20 F at Lone Pine Idaho.
The wind chill temperature fell to -20 F at Lost Trail Pass Idaho.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2010Every state in 2010This day in weather historyWarnings in Idaho, December 2010
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: 272850, 272852, 272851.