A strong westerly flow aloft combined with the passage of several shortwaves, resulted in a tight surface pressure gradient and high winds over a large portion of North Central Montana.
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 strong westerly flow aloft combined with the passage of several shortwaves, resulted in a tight surface pressure gradient and high winds over a large portion of North Central Montana.
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 7, 4:35 AM MST, 2 hours 46 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 435 AM MST MON DEC 7 2015 AVIATION SECTION UPDATED .DISCUSSION... TODAY THROUGH WEDNESDAY...A STRONG WESTERLY FLOW ALOFT WITH SIGNIFICANT PACIFIC MOISTURE WILL BRING WINDY CONDITIONS WITH MAINLY MOUNTAIN PRECIPITATION FOR MUCH OF THIS PERIOD. A SERIES OF WEAK SHORTWAVE TROUGHS WILL DETERMINE THE TIMING FOR THE BEST CHANCES FOR STRONG WINDS AND PRECIPITATION. SHORTWAVE PASSAGES TONIGHT AND THEN AGAIN TUESDAY NIGHT INTO WEDNESDAY BRING GUSTS UP TO 70 MPH TO THE PLAINS AND UP TO 80 MPH ALONG THE ROCKY MOUNTAIN FRONT. IT SEEMS THAT GUSTS WILL BE A BIT MORE SPORADIC ACROSS THE EASTERN TFX PLAINS OF HILL, BLAINE, AND FERGUS COUNTIES, BUT GUSTS THERE COULD REACH 65 MPH AT TIMES IN SOME OF THE FAVORED AREAS, SO HAVE UPGRADED THEIR HIGH WIND WATCH TO A WARNING. HOWEVER, THERE IS A GOOD CHANCE THAT THERE WILL BE SIGNIFICANT LULLS IN THE WINDS IN BETWEEN THE SHORTWAVE PASSAGES. ANOTHER SHORTWAVE WILL APPROACH THE AREA ON WEDNESDAY, WHICH MAY CAUSE BORDERLINE STRONG WINDS. THE WARNINGS MAY NEED TO BE EXTENDED INTO WEDNESDAY NIGHT, BUT THIS WILL BE FURTHER EVALUATED OVER THE NEXT FEW SHIFTS. WITH TEMPERATURES RUNNING 15 TO 20 DEGREES ABOVE NORMAL DUE TO THE DOWNSLOPING WINDS, RELATIVE HUMIDITIES WILL ALSO FALL TO AROUND 30 PERCENT DURING THE AFTERNOONS. THEREFORE, THE CONCERNS OUTLINED IN THE FIRE WEATHER DISCUSSION SECTION REMAIN VALID. PRECIPITATION WILL BE MOSTLY LIMITED TO THE MOUNTAINS THROUGH WEDNESDAY, YIELDING POTENTIALLY 6 TO 12 INCHES OF WET SNOW ABOVE 7500 FEET IN PORTIONS OF SOUTHWEST MONTANA AND 10 TO 20 INCHES ABOVE 7000 FEET ALONG THE ROCKY MOUNTAIN FRONT. AS THESE ELEVATIONS ARE WELL ABOVE THE MOUNTAIN PASSES, IMPACTS TO TRAVEL WILL BE MINIMAL. BLOWING SNOW WILL REDUCE VISIBILITY AT TIMES THROUGH MARIAS PASS, BUT LITTLE IF ANY SNOW IS EXPECTED TO ACCUMULATE ON THE ROAD. AREAS OF LIGHT RAIN WILL BE POSSIBLE AT LOWER ELEVATIONS WITH EACH SHORTWAVE PASSAGE, BUT SIGNIFICANT PRECIPITATION IS NOT EXPECTED THERE. COULSTON WEDNESDAY NIGHT THROUGH MONDAY...PERIOD BEGINS WITH SHORTWAVE TROF EXITING OUR REGION AND HEADING INTO EASTERN MT/DAKOTAS BY WED NIGHT. GOOD CHANCE WINDS WILL STILL BE GUSTY THROUGH WED EVENING BUT THEN SHOULD STEADILY DECREASE OVERNIGHT AS WEAK TRANSIENT HIGH PRESSURE RIDGE MOVES OVER OUR REGION THROUGH THUR MORNING. ONCE THE RIDGE HEADS DOWNSTREAM ON THURS AFTN, A BROAD, SLOW-MOVING PACIFIC TROF WILL BRING GENERALLY UNSETTLED WEATHER CONDITIONS. PERIODS OF SCATTERED RAIN AND SNOW SHOWERS ARE EXPECTED FROM THURS EVE UNTIL EARLY SAT WITH HIGH TEMPERATURES GRADUALLY COOLING BACK INTO THE 30S BY SAT. GIVEN THE FAIRLY DIFFUSE MOISTURE PATTERN WITH THIS SYSTEM, MOST CENTRAL AND HILINE COUNTIES WILL STRUGGLE TO RECEIVE MORE THAN A FEW HUNDREDTHS OF AN INCH OF PRECIPITATION. BETTER CHANCES FOR A TENTH OF AN INCH OR MORE OF PRECIP WILL OCCUR OVER SOUTHWEST MT. THE BROAD TROF HEADS INTO GREAT PLAINS ON SUN, ALLOWING FOR A SECOND TRANSIENT RIDGE TO MOVE ACROSS THE STATE, BUT ANOTHER MOIST PACIFIC SHORTWAVE IS CLOSE BEHIND, BRINGING A REPEAT OF THE SCATTERED SHOWERS ON MON. WARANAUSKAS && .AVIATION... UPDATED 1135Z. VFR CONDITIONS EXPECTED TODAY. EXTENSIVE PLUMES OF PACIFIC MOISTURE CONTINUE TO STREAM OVER CENTRAL/SOUTHWEST MT THANKS TO STRONG WESTERLY WINDS ALOFT, CREATING WIDESPREAD MID-LEVEL (GENERALLY ABOVE 10000 FT) CEILINGS. AN UPPER-LEVEL TROUGH EMBEDDED WITHIN THE FLOW WILL PASS THROUGH THE REGION THIS EVENING WITH ISOLATED TO SCATTERED -SHRASN THAT WILL LOWER CEILINGS AT SOME TAF SITES TO 5000-6000 FT. GUSTY TO STRONG SURFACE WINDS WILL DEVELOP BY LATE MORNING/MIDDAY VCNTY KCTB/KHVR/KGTF/KLWT AHEAD OF THE TROUGH AXIS WITH WIDESPREAD GUSTS OF 35 TO 45 KTS CONTINUING INTO THIS EVENING. WARANAUSKAS && .FIRE WEATHER... VERY WINDY AND DRY CONDITIONS ARE EXPECTED THROUGH WEDNESDAY ACROSS ALL OF NORTH CENTRAL MONTANA. GRASSLAND FIRE DANGER INDICES HAVE PEGGED OUT AT VERY HIGH TO EXTREME OVER THE PLAINS EACH DAY DURING THIS PERIOD. LATEST MODELS CURRENTLY INDICATE THAT MINIMUM RELATIVE HUMIDITY VALUES SHOULD REMAIN ABOVE 25% SO I DO NOT ANTICIPATE THAT ANY FIRE WEATHER HIGHLIGHTS WILL NEED TO BE ISSUED AT THIS TIME. HOWEVER, CONDITIONS ARE BORDERLINE ENOUGH THAT ANY GRASS FIRES THAT IGNITE COULD POTENTIALLY GROW VERY RAPIDLY AND DANGEROUSLY. ADDITIONALLY, DOWNSLOPE WINDS COULD HEAT AND DRY THE ATMOSPHERE MORE THAN MODELS CURRENTLY INDICATE SO FELT CONDITIONS WERE SUFFICIENT TO ISSUE A "HEADS UP" TO OUR FIRE WEATHER PARTNERS. MPJ && .PRELIMINARY POINT TEMPS/POPS... GTF 52 43 56 48 / 0 30 10 10 CTB 49 35 53 42 / 0 40 10 20 HLN 50 41 56 43 / 10 40 20 10 BZN 50 34 55 36 / 10 40 20 10 WEY 33 18 37 22 / 60 80 50 40 DLN 45 36 50 38 / 20 50 20 10 HVR 53 35 55 42 / 10 50 10 10 LWT 52 39 55 42 / 10 40 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM 6 PM THIS EVENING TO 6 AM MST WEDNESDAY FOR MTZ011>013-044>047-049>051-054. HIGH WIND WARNING FROM NOON TODAY TO 6 AM MST WEDNESDAY FOR MTZ009-010-014-048. && WEATHER.GOV/GREATFALLS
16 high wind. Local standard time, as filed.
A wind gust to 60 mph was reported at East Glacier Park 1ENE (the Two Medicine DOT site). Also, a gust to 67 mph was reported at Heart Butte.
A wind gust to 63 mph was reported at McAllister 4NNE (the Norris Hill DOT site).
A wind gust to 58 mph was reported at Cut Bank 3SW (the Cut Bank ASOS site).
A wind gust to 82 mph was reported at Bynum 13W (the Dellwo MCSCN site).
A wind gust to 58 mph was reported at Augusta 12NNE.
A wind gust to 67 mph was reported at White Sulphur Springs 1SE.
A wind gust to 76 mph was reported at Cascade.
A wind gust to 68 mph was reported at Helena 3ENE (the Helena ASOS site).
A wind gust to 61 mph was reported at Garneill 4S. Also, a gust to 61 mph was reported at Denton 5ESE.
A wind gust to 67 mph was reported at Sunburst 6NNW (the Sweetgrass Hills DOT site).
A wind gust to 72 mph was reported at Fort Benton 8SSW.
A wind gust to 61 mph was reported at Winston 6SE.
A wind gust to 59 mph was reported at Moccasin 3WSW.
A wind gust to 70 mph was reported at Bozeman 11E (Bozeman Pass DOT site).
A wind gust to 62 mph was reported at Chester 17N.
A wind gust to 58 mph was reported at Fort Belknap 13S (the Fort Belknap RAWS site).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2015Every state in 2015This day in weather historyWarnings in Montana, December 2015
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: 608442, 608443, 608445, 608444, 608446, 608447, 608448, 608449, 608451, 608450, 608454, 608453, 608457, 608452, 608455, 608456.