A powerful Pacific storm system with abundant moisture interacted with a very cold arctic air mass to produce heavy snow with areas of blowing snow and very cold wind chill temperatures.
Every event with a place to put it; 1 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 powerful Pacific storm system with abundant moisture interacted with a very cold arctic air mass to produce heavy snow with areas of blowing snow and very 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 28, 1:22 PM PST, 4 hours 38 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
222 PM MST TUE DEC 28 2010
...A STRONG WINTER STORM WILL IMPACT THE NORTHERN ROCKIES REGION
LATE TONIGHT THROUGH WEDNESDAY NIGHT...
...TURNING MUCH COLDER WEDNESDAY NIGHT AND THURSDAY...
.DISCUSSION...A STRONG LOW PRESSURE SYSTEM WILL SWING THROUGH THE
NORTHERN ROCKIES TONIGHT THROUGH WEDNESDAY CAUSING A WINTER STORM
FOR ALL PORTIONS OF THE NORTHERN ROCKIES. THIS SYSTEM HAS A
SUBSTANTIAL MOISTURE FEED WHICH WILL CAUSE WIDESPREAD MODERATE TO
HEAVY SNOW ACCUMULATIONS. THE MOUNTAINS SHOULD SEE AROUND 1 TO 2
FEET OF NEW SNOW...WHILE THE VALLEYS EXPERIENCE 4 TO 10 INCHES OF
SNOW. THE PATH OF THE SURFACE LOW IS NOW EXPECTED TO BE SLIGHTLY
FARTHER NORTH THEN PREVIOUS FORECAST...WHICH SHOULD KEEP THE
HEAVIEST SNOW ALONG THE MONTANA IDAHO BORDER UP INTO NORTHWEST
MONTANA. ALSO AS THIS SYSTEM APPROACHES THE PRESSURE GRADIENT WILL
TIGHTEN OVER NORTHWEST MONTANA CAUSING GUSTY NORTHEASTERLY WINDS.
THE COMBINATION OF THE WINDS AND SNOW WILL CAUSE BLOWING AND
DRIFTING WITH LOCALLY WHITE OUT CONDITIONS ESPECIALLY IN THE
NORTHERN FLATHEAD VALLEY INTO THE GLACIER PARK REGION. THE LOWER
VALLEYS OF NORTH CENTRAL IDAHO ARE EXPECTED TO EXPERIENCE RAIN
BEFORE TRANSITIONING OVER TO SNOW AFTER THE PASSAGE OF THE COLD
FRONT. WARNINGS AND ADVISORIES HAVE BEEN ISSUED FOR THIS SYSTEM.
THE LOW PRESSURE SYSTEM WILL MOVE QUICKLY OFF TO THE EAST
WEDNESDAY AFTERNOON AND OVERNIGHT ALLOWING FOR A CANADIAN AIR MASS
TO SETTLE OVER THE NORTHERN ROCKIES. THIS COLDER AIR MASS WILL
ALLOW TEMPERATURE TO DROP WELL BELOW NORMAL FOR THIS TIME OF YEAR
FOR WEDNESDAY NIGHT. THE REGION COULD EXPERIENCE A SHOT OF SNOW
ALONG THE LEADING EDGE OF THE COLD AIR AS IT MOVES INTO THE
NORTHERN ROCKIES...ESPECIALLY ACROSS WESTERN MONTANA.
THURSDAY THROUGH TUESDAY...FRIGID TEMPERATURES ARE IN STORE FOR THE
END OF THIS YEAR WITH SOME WELL BELOW ZERO LOWS EXPECTED FRIDAY
MORNING. TEMPERATURES WILL NOT BE INCREASING MUCH THROUGH THE DAY
INTO NEW YEARS EVE. IT SHOULD ALSO REMAIN VERY COLD FOR THE START OF
THE WEEKEND THEN MODERATE EACH DAY AFTERWARD WITH A BETTER CHANCE OF
SNOW AS PACIFIC AIR MOVES INTO THE NORTHERN ROCKIES.
&&
.AVIATION...A LOW PRESSURE SYSTEM APPROACHING THE REGION HAS BEEN
PRODUCING SNOW IN THE HIGH TERRAIN...BUT AS IT MAKES ITS WAY OVER
IDAHO AND MONTANA WIDESPREAD SNOWFALL IS EXPECTED. ONCE THE GRADIENT
THAT HAS BEEN PRODUCING WIND AT KMSO WEAKENS AND THE WIND RELAXES
SNOW WILL BEGIN AND CEILINGS AND VISIBILITIES WILL DROP. SOME OF
THESE REDUCTIONS WILL BE SEEN LATE THIS EVENING BUT THE MAIN IMPACT WILL
BE DURING THE DAY ON WEDNESDAY WHEN THE MOISTURE AND LIFT ARE AT
THEIR PEAK. KGPI WILL NOT ONLY SEE THEN SNOW BUT STRONG NORTHEAST
WINDS WILL DEVELOP BY WEDNESDAY MORNING THAT WILL CAUSE BLOWING
SNOW AND EVEN MORE REDUCTIONS TO VISIBILITY. ALL AIRFIELDS IN THE
REGION WILL SEE NEGATIVE IMPACTS FROM THIS SYSTEM DURING WEDNESDAY
AND THE SYSTEM WILL LINGER THROUGH WEDNESDAY NIGHT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 2 AM WEDNESDAY TO 5 AM MST THURSDAY
BUTTE/BLACKFOOT REGION.
WINTER STORM WARNING UNTIL 5 AM MST THURSDAY BITTERROOT/SAPPHIRE
MOUNTAINS...LOWER CLARK FORK REGION.
WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 5 AM MST THURSDAY
MISSOULA/BITTERROOT VALLEYS.
WINTER STORM WARNING FROM 11 PM THIS EVENING TO 5 AM MST
THURSDAY FLATHEAD/MISSION VALLEYS.
WINTER STORM WARNING UNTIL 5 AM MST THURSDAY WEST GLACIER REGION.
WINTER STORM WARNING UNTIL 5 AM MST THURSDAY KOOTENAI/CABINET
REGION.
WINTER STORM WARNING FROM 2 AM WEDNESDAY TO 5 AM MST THURSDAY
POTOMAC/SEELEY LAKE REGION.
ID...WINTER STORM WARNING UNTIL 5 AM MST THURSDAY EASTERN LEMHI
COUNTY.
WINTER STORM WARNING UNTIL 4 AM PST THURSDAY NORTHERN CLEARWATER
MOUNTAINS...SOUTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 AM WEDNESDAY TO 10 AM PST
THURSDAY FOR WHITE BIRD GRADE.
WINTER WEATHER ADVISORY FROM 4 AM WEDNESDAY TO 10 AM PST
THURSDAY OROFINO/GRANGEVILLE REGION.
WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 5 AM MST THURSDAY
WESTERN LEMHI COUNTY.
&&
SHORT TERM...SMITH
LONG TERM....SIGLER
AVIATION...KITSMILLERThe national radar mosaic for the moment the first event began.
1 avalanche. Local standard time, as filed.
Spotter in Dixie reported 14 inches of snow and a spotter in Powell reported 13 inches of snow.
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 2026-09-24. Each event’s entry at NCEI: 272864.