A Pacific storm brought heavy snow to portions of Southwest Montana. Snow amounts in excess of 8 inches were reported.
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 TFX wrote it up.
A Pacific storm brought heavy snow to portions of Southwest Montana. Snow amounts in excess of 8 inches were reported.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Dec 20, 4:37 PM MST, 3 hours 23 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 437 PM MST TUE DEC 20 2011 UPDATED AVIATION DISCUSSION .DISCUSSION... TONIGHT THROUGH THURSDAY...WINDS WILL CONTINUE TO DECREASE ALONG THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS TODAY SO HAVE CANCELLED THE HIGH WIND WARNING. MODELS REMAIN IN DISAGREEMENT REGARDING THE PACIFIC STORM SYSTEM MOVING INTO THE FORECAST AREA TONIGHT. GFS REMAINS TO BE THE WETTEST MODEL WHILE THE NAM IS THE DRIEST AND THE ECMWF IS SOMEWHERE IN-BETWEEN. AN UPPER-LEVEL TROUGH WILL SWING INTO THE NORTHERN ROCKIES OVERNIGHT WITH PACIFIC MOISTURE INCREASING...PARTICULARLY ACROSS SOUTHWEST MONTANA. MODELS HINT AT BEST LIFT AND MOISTURE OVER SOUTHWEST MONTANA WITH AN UPPER-LEVEL JET ALSO SUPPORTING MAX LIFT. GIVEN THE FAVORABLE JET AND MID-LEVEL DYNAMICS ALONG WITH OROGRAPHICS AND INCREASING MOISTURE HAVE UPGRADED THE WINTER STORM WATCH FOR GALLATIN COUNTY TO A WINTER STORM WARNING FOR ELEVATIONS ABOVE 6000 FEET. ALSO INCLUDED MADISON COUNTY ABOVE 6000 FEET MAINLY TO HIGHLIGHT THE MADISON RANGE AND TOBACCO ROOTS. SNOW AMOUNTS IN THESE AREAS OF 8 TO 14 INCHES ARE POSSIBLE. KEPT INHERITED WINTER WEATHER ADVISORY FOR THE REMAINDER OF CENTRAL AND SOUTHWEST MONTANA...THOUGH SNOW AMOUNTS MAY BE MUCH LOWER THAN PREVIOUSLY THOUGHT...ESPECIALLY OVER THE PLAINS WHERE 1 TO 3 INCHES IS POSSIBLE BUT EVEN THAT MAY BE GENEROUS. ACROSS THE SOUTHWEST MONTANA VALLEYS...SNOW AMOUNTS OF 2 TO 5 INCHES ARE POSSIBLE. BEST PRECIPITATION CHANCES IN CENTRAL MONTANA WILL BE ALONG AND BEHIND A COLD FRONTAL PASSAGE EXPECTED TO MOVE OVER THE AREA AFTER MIDNIGHT. OTHER CONCERN IS FOR THE LITTLE/BIG BELT MOUNTAINS WHERE SNOWFALL AMOUNTS ARE INCONSISTENT IN THIS AREA. NAM AND GFS HAVE A SECONDARY SHORTWAVE BEHIND THE COLD FRONT ON WEDNESDAY SO THERE MAY BE A BREAK IN PRECIPITATION WEDNESDAY MORNING WITH ADDITIONAL LIGHT SNOWFALL BY MIDDAY WEDNESDAY. HAVE KEPT A WINTER WEATHER ADVISORY FOR THIS AREA GIVEN THE AMOUNT OF UNCERTAINTY. SNOW WILL TAPER WEDNESDAY MORNING ALONG THE CONTINENTAL DIVIDE AND PARTS OF CENTRAL MONTANA AND THEN END BY WEDNESDAY EVENING IN THE EASTERN PORTIONS OF THE FORECAST AREA AS THE UPPER TROUGH MOVES FARTHER EAST. HIGH TEMPERATURES WILL FALL INTO THE 20S ON WEDNESDAY AND THEN RISE TO AROUND FREEZING ON THURSDAY. MLV THURSDAY NIGHT THROUGH TUESDAY...EXPECT A RATHER BREEZY AND MILD PERIOD OF WEATHER OVER THE REGION FOR MUCH OF THE EXTENDED PERIOD. OVERALL...EITHER A BRISK WESTERLY FLOW OR SLIGHTLY UPPER LEVEL RIDGING WILL BE OVER THE REGION FROM FRIDAY THROUGH TUESDAY. THIS WILL RESULT IN BREEZY CONDITIONS OVER THE REGION AND LIMIT THE CHANCES FOR ANY PRECIPITATION. FOR NOW...MOST OF THE PRECIPITATION IS EXPECTED TO BE CONFINED MAINLY TO THE MOUNTAIN AREAS FROM FRIDAY THROUGH TUESDAY...WITH ANY SNOWFALL BEING ON THE LIGHT SIDE...GENERAL LESS THAN AN INCH PER DAY. IT WILL BE QUITE WINDY ON FRIDAY...ESPECIALLY OVER THE ROCKY MOUNTAIN FRONT. HIGH WIND HIGHLIGHTS COULD BE ISSUED LATER IN THE WEEK FOR THIS EVENT. IN TERMS OF TEMPERATURES...MILD AIR WILL GENERALLY RESIDE OVER NORTH CENTRAL MONTANA...WITH AFTERNOON HIGHS RUNNING ABOUT 4 TO 8 DEGREES ABOVE NORMAL. IN SOUTHWEST MONTANA...WITH OVERNIGHT LOWS A BIT COOLER IN THE VALLEYS...EXPECT AFTERNOON TEMPERATURES A BIT CLOSER TO NORMAL. AGAIN...NO MAJOR STORMS ARE EXPECTED OVER THE CHRISTMAS WEEKEND AT THIS TIME...BUT WITH SOME WIND...AREAS OF BLOWING SNOW COULD CAUSE A FEW MINOR PROBLEMS FROM TIME TO TIME. BRUSDA && .AVIATION... UPDATED 0000Z. AN UPPER LEVEL TROUGH WILL DIG SOUTHEAST INTO THE NORTHERN ROCKIES TONIGHT WITH A WESTERLY FLOW ALOFT VEERING TO THE NORTHWEST AND BECOMING INCREASINGLY MOIST AND SOMEWHAT UNSTABLE THROUGH THIS EVENING. EXPECT LOWERING CLOUD BASES AND INCREASING MTN OBSCURATION THROUGH THIS EVENING WITH SNOW SHOWERS DEVELOPING AND INCREASING IN COVERAGE AND INTENSITY LATER TONIGHT. THE MOST WIDESPREAD AND PERSISTENT SUB-VFR CONDITIONS WILL BE ACROSS CENTRAL AND SW MT WITH A SECONDARY WAVE OF MOISTURE BRINGING MORE WIDESPREAD SNOW SHOWERS TO NORTH CENTRAL MT ON WEDNESDAY. GUSTY WESTERLY SURFACE WINDS WILL VEER TO NORTHWEST THIS EVENING AND REMAIN OUT OF THE NW THROUGH WEDNESDAY. HOENSICH && .PRELIMINARY POINT TEMPS/POPS... GTF 22 28 15 32 / 80 60 20 0 CTB 18 27 11 31 / 40 40 10 0 HLN 23 27 8 28 / 80 70 20 0 BZN 24 25 -1 25 / 80 80 20 0 WEY 12 20 -13 15 / 80 90 30 10 DLN 22 27 6 28 / 70 70 20 0 HVR 21 29 9 34 / 40 30 10 0 LWT 19 25 8 29 / 70 70 20 0 && .TFX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 11 PM MST WEDNESDAY BEAVERHEAD...BROADWATER...CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK...EASTERN TETON...FERGUS...JEFFERSON... JUDITH BASIN...MEAGHER...SOUTHERN ROCKY MOUNTAIN FRONT. WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 11 PM MST WEDNESDAY FOR ELEVATIONS BELOW 6000 FEET FOR GALLATIN...MADISON. WINTER STORM WARNING FROM 8 PM THIS EVENING TO 11 PM MST WEDNESDAY FOR ELEVATIONS ABOVE 6000 FEET FOR GALLATIN...MADISON. && WEATHER.GOV/GREATFALLS
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE GREAT FALLS MT 630 AM MST TUE DEC 20 2011 MTZ009>010-048-211200- NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER- SOUTHERN ROCKY MOUNTAIN FRONT- 630 AM MST TUE DEC 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT A HIGH WIND WARNING REMAINS IN EFFECT UNTIL 6 PM MST THIS EVENING. A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE SOUTHERN ROCKY MOUNTAIN FRONT FOR TONIGHT. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE SOUTHERN ROCKY MOUNTAIN FRONT THROUGH THE DAY ON WEDNESDAY. STRONG WINDS ARE POSSIBLE OVER THE ROCKY MOUNTAIN FRONT AND THE CUT BANK AREA AGAIN THURSDAY NIGHT THROUGH FRIDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MTZ011-013-044>047-211200- HILL-CHOUTEAU-TOOLE-LIBERTY-EASTERN PONDERA-BLAINE- 630 AM MST TUE DEC 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MTZ008-012-014-015-049>054-211200- BEAVERHEAD-CASCADE-CENTRAL AND SOUTHERN LEWIS AND CLARK-MADISON- EASTERN TETON-JUDITH BASIN-FERGUS-JEFFERSON-BROADWATER-MEAGHER- 630 AM MST TUE DEC 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT A WINTER WEATHER ADVISORY IN EFFECT FROM 8 PM THIS EVENING TO 5 PM MST WEDNESDAY FOR PORTIONS OF CENTRAL AND SOUTHWEST MONTANA. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THE WINTER WEATHER ADVISORY CONTINUES THROUGH WEDNESDAY AFTERNOON. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MTZ055-211200- GALLATIN- 630 AM MST TUE DEC 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST MONTANA. .DAY ONE...TODAY AND TONIGHT A WINTER STORM WATCH IN EFFECT FROM THIS EVENING THROUGH WEDNESDAY EVENING FOR GALLATIN COUNTY. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THE WINTER STORM WATCH CONTINUES THROUGH WEDNESDAY EVENING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
209 PM MST TUE DEC 20 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0417 PM NON-TSTM WND GST 1 E EAST GLACIER PARK 48.45N 113.19W
12/19/2011 M58 MPH GLACIER MT MESONET
58 MPH WIND GUST MEASURED AT DOT SENSOR NEAR TWO
MEDICINE BRIDGE.
&&
NJL3 winter storm. Local standard time, as filed.
Nine inches of snow fell at Cameron 15SSW (the Clover Meadow SNOTEL site - elevation 8800 feet). Also, nine inches of snow fell at Big Sky 5W.
Eight inches of snow fell at Gallatin Gateway 18SE (the Shower Falls SNOTEL site - elevation 8100 feet). Also, eight inches of snow fell at West Yellowstone 11S (the Black Bear SNOTEL site - elevation 7949 feet) and 12 inches of snow fell at Gallatin Gateway 13ESE (the Lick Creek SNOTEL site - elevation 6860 feet).
Nine inches of snow fell at Marysville 1WNW (the Great Divide Ski Area).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2011Every state in 2011This day in weather historyWarnings in Montana, December 2011
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: 355293, 355295, 355296.