A tight surface pressure gradient with an associated strong cold front produce very strong winds across western Montana.
Every event with a place to put it; 8 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 tight surface pressure gradient with an associated strong cold front produce very strong winds across western 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 Missoula, MT wrote its last area forecast discussion before the first event at Feb 12, 4:17 AM MST, 2 hours 37 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
417 AM MST SAT FEB 12 2011
...WINDY TODAY AND TONIGHT ACROSS THE ENTIRE NORTHERN ROCKIES...
...SNOW AND BLOWING SNOW IN THE MOUNTAINS OF NORTHWEST MONTANA
LATE THIS AFTERNOON THROUGH SUNDAY MORNING...
...TEMPERATURES IN THE 40S IN THE VALLEYS OF WESTERN MONTANA TODAY...
.DISCUSSION... A RIDGE OF HIGH PRESSURE WILL FLATTEN TODAY AND TONIGHT AS
A VERY STRONG 150 KNOT JET NOSES ITS WAY INTO THE REGION. A RESULTANT
SOUTHERLY SURFACE PRESSURE GRADIENT WILL CONTINUE TO STRENGTHEN PRODUCING
CONDITIONS FAVORABLE FOR STRONG GUSTY SOUTH WINDS. STRONG GUSTY WINDS
ARE ALREADY OCCURRING IN GARRISON JUNCTION TO AVON, GRANGEVILLE AND THE
I-90 CORRIDOR FROM BUTTE TO GARRISON JUNCTION. WIND ADVISORIES ARE
IN EFFECT FOR THESE AREAS THROUGH TONIGHT. GUSTY 20-30 MPH WINDS
WILL DEVELOP IN BITTERROOT VALLEY TODAY. WINDS WILL INTENSIFY THIS
EVENING AND OVERNIGHT WITH GUSTS OF 40 MPH TO NEAR 50 MPH
POSSIBLE. THUS A WIND ADVISORY HAS BEEN ISSUED FOR THE BITTERROOT
VALLEY TONIGHT. WIDESPREAD VALLEY HIGH TEMPERATURES IN THE 40S ARE
LIKELY TODAY WITH TEMPERATURES AROUND 50 POSSIBLE IN THE SOUTHERN
BITTERROOT VALLEY.
MOISTURE MOVING OFF THE PACIFIC OCEAN WILL SPREAD ACROSS NORTHWEST MONTANA
THIS EVENING AND OVERNIGHT...COINCIDING WITH THE STRONGEST WESTERLY
WINDS FLOW. SNOW LEVELS WILL LOWER ACROSS NORTHWEST OVERNIGHT WITH
ACCUMULATING SNOW EXPECTED RETURNING TO THE VALLEYS ALONG THE CONTINENTAL
DIVIDE...NORTH OF HIGHWAY 200. THE COMBINATION OF SNOW AND WIND WILL
MAKE FOR DIFFICULT TRAVEL IN THE MOUNTAINS...ESPECIALLY OVER MARIAS
PASS. WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR THE SEELEY-SWAN
ROUTE ALONG HWY 83... AS WELL AS THE WEST GLACIER REGION TONIGHT.
FARTHER SOUTH.
BREEZY CONDITIONS ARE EXPECTED TO PERSIST THROUGH MONDAY AND
TUESDAY AS A SOUTHERLY SURFACE PRESSURE GRADIENT MAINTAINS ITSELF
ACROSS THE REGION. FORECAST MODELS ARE STRUGGLING TO AGREE WITH
THE AMOUNT AND PLACEMENT OF MOISTURE PUSHING INTO THE NORTHERN
ROCKIES ON MONDAY. AT THIS TIME THERE IS AGREEMENT ACROSS NORTHWEST
MONTANA FOR POINTS GENERALLY NORTH OF INTERSTATE 90 SO HAVE
INCREASED POPS ACROSS THIS REGION.
HOWEVER OVERNIGHT INTO TUESDAY ALL MODELS NOW AGREE THAT THE
RIDGE WILL FINALLY BREAK DOWN ALLOWING MOISTURE TO SURGE ACROSS
THE MOUNTAINS OF IDAHO AND MONTANA AHEAD OF A STRONG 140 KNOT JET
STREAM. THE PASSAGE OF A SURFACE COLD FRONT IN SYNC WITH THE UPPER
JET COULD LEAD TO SOME IMPRESSIVE WIND GUSTS ON TUESDAY
MORNING/AFTERNOON AS WELL AS SOME HEAVY PRECIPITATION ALONG THE
FRONTAL BOUNDARY. TIMING OF THIS FRONT IS STILL SOMEWHAT IN
QUESTION SO HAVE ADJUSTED TEMPERATURES AND SNOW LEVELS
CONSERVATIVELY TO BETTER REFLECT THE TYPICAL FRONTAL PASSAGES THIS
TIME OF THE YEAR. HOWEVER...IF THIS FRONTAL PASSAGE IS AS SLOW AS
SOME MODELS SUGGEST A PROLONGED PERIOD OF FOCUSED...HEAVY
PRECIPITATION MAY BE POSSIBLE OVER THE AREA.
AFTER THE COLD FRONT PASSES TO THE EAST TEMPERATURES ACROSS THE
ENTIRE AREA WILL RETURN TO NORMAL...IF NOT SOMEWHAT BELOW NORMAL LEVELS.
BUT FORECAST MODELS ARE ALL OVER THE MAP FOR THE WEATHER PATTERN
BEYOND MIDWEEK WITH THE ECMWF SHOWING A RATHER STRONG ARCTIC
COMING DOWN FROM CANADA...THE GFS SHOWING BROAD TROUGHING WHILE
KEEPING THE ARCTIC MAINLY OVER NORTH DAKOTA AND THE CANADIAN MODEL
STALLING THE FRONTAL PASSAGE UNTIL LATE THURSDAY. THUS HAVE MADE
CONSERVATIVE CHANGES TO THE FORECAST FOR WEDNESDAY AND BEYOND
WHICH BASICALLY FOLLOWED THE TREND OF A LARGE TROUGH DEVELOPING
OVER THE WESTERN UNITED STATES. THIS WOULD BRING AT LEAST NORMAL
TEMPERATURES WITH CONTINUED CHANCES FOR SNOW THROUGH THE REMAINDER
OF THE WEEK.
&&
.AVIATION...SOUTHWEST WINDS WILL BE INCREASING TODAY THROUGH SATURDAY
NIGHT. GUSTY WINDS TO NEAR 40 MPH ARE ANTICIPATED AT KBTM THIS
MORNING THROUGH SATURDAY NIGHT. WIND GUSTS OF 20-30 MPH ARE
EXPECTED AFTER 12/1900Z THROUGH 13/1200Z AT KMSO AND KGPI.
NORTHWEST MONTANA MOUNTAINS WILL BECOME MOSTLY OBSCURED AS A SURGE
OF MOISTURE ARRIVES SATURDAY EVENING.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY UNTIL 11 AM MST SUNDAY BUTTE/BLACKFOOT REGION.
WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST SUNDAY
MISSOULA/BITTERROOT VALLEYS.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST
SUNDAY WEST GLACIER REGION.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST
SUNDAY FOR HIGHWAY 83 SEELEY LAKE TO CONDON.
ID...WIND ADVISORY UNTIL 8 AM PST SUNDAY FOR GRANGEVILLE AND VICINITY.
WIND ADVISORY UNTIL 8 AM PST SUNDAY FOR THE CAMAS PRAIRIE AND
HIGHWAY 95 BETWEEN WHITE BIRD AND RIGGINS.
&&
SHORT TERM...RPN
LONG TERM....DICKERSON
AVIATION...RPNThe national radar mosaic for the moment the first event began.
8 high wind. Local standard time, as filed.
Sustained wind of 23 mph with gust to 59 mph observed at MDOT site near Georgetown lake on MT-1.
Sustained wind of 40 mph gusting to 57 mph was reported at a MDOT site near Avon north on MT-141.
Power lines and several business signs were blown down in Libby.
Southwest winds of 32 mph with gusts to 68 mph were reported at Zonolite.
Kila coop observer reported southwest winds 40 mph gusting to 53 mph.
Tepee Point RAWS at 6629 feet reported a gust to 59 mph.
Sustained wind of 39 mph gusting to 77 mph was reported at 7929 feet, on Point Six mountain.
Sustained wind of 33 mph with gusts to 59 mph reported by Fielding RAWS at 6629 feet, 6 miles east of Essex.
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, February 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: 279980, 279981, 279983, 279984, 279985, 280090, 280081, 280082.