An upper level low off of the Washington coast and a strong jet stream helped develop and intensify a surface low and associated cold front. This system brought damaging winds and some brief heavy snowfall to the region.
Every event with a place to put it; 4 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.
An upper level low off of the Washington coast and a strong jet stream helped develop and intensify a surface low and associated cold front. This system brought damaging winds and some brief heavy snowfall to the region.
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 Mar 13, 2:23 AM PST, 1 hour 2 minutes earlier.
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MISSOULA MT
423 AM MDT TUE MAR 13 2012
...CORRECTED TO MAKE THE WINTER WEATHER ADVISORY FOR THE
KOOTENAI/CABINET REGION ABOVE 2500 FEET...
...DAMAGING WINDS LIKELY WITHIN GRANGEVILLE/CAMAS PRAIRIE REGION
OF NORTH CENTRAL IDAHO THIS MORNING...
.DISCUSSION...TWO DISTINCT IMPACTS ARE ANTICIPATED TODAY.
WIND: A VERY STRONG SURFACE COLD FRONT IS PRESENTLY MARCHING EAST
OVER THE CASCADE MOUNTAINS. WIND SPEED READINGS ACROSS EASTERN
WASHINGTON/OREGON AND PARTS OF WESTERN IDAHO HAVE BEEN STEADILY
INCREASED AHEAD OF THE COLD FRONT...MATCHING WHAT WAS PREVIOUSLY
FORECAST. THE LATEST OBSERVATIONS IN GRANGEVILLE SHOW WINDS GUSTING
TO 55 MPH AND BELIEVE THAT GUSTS TO 70 MPH CAN BE EXPECTED THIS
MORNING AS FAVORABLE CONDITIONS WILL DEVELOP AT THE MOUNTAIN TOP
LEVEL...FORCING INCREASING UPPER LEVEL WINDS TOWARDS THE SURFACE.
FORECAST MODELS ALL STILL SHOW GUSTY CONDITIONS APPROACHING WIND
ADVISORY CRITERIA ACROSS MUCH OF CENTRAL IDAHO AS WELL AS PARTS OF
WESTERN MONTANA LATE THIS MORNING THROUGH THIS EVENING. SO ALL
OTHER WIND ADVISORIES PREVIOUSLY ISSUED WILL CONTINUE UNCHANGED.
IT IS POSSIBLE THAT THE WIND SPEEDS MAY FALL A BIT SOONER IN SOME
LOCATIONS...DEPENDING UPON HOW QUICKLY THE FRONT PASSES THROUGH
THE TERRAIN. BUT DID NOT HAVE ENOUGH CONFIDENCE IN THIS NOR
BELIEVE IT SIGNIFICANT ENOUGH OF A DIFFERENCE TO ADJUST THE END
TIMES OF THE ALREADY ISSUED WIND HIGHLIGHTS.
SNOW: THE BIGGEST CHANGE TO THE PRECIPITATION/SNOWFALL FORECAST
WAS TO ADD A WINTER WEATHER ADVISORY FOR LOCATIONS ABOVE 2500 FEET
IN NORTHWEST MONTANA AND THE GLACIER PARK REGION. TEMPERATURES BY
AND LARGE HAVE CHANGED LITTLE OVERNIGHT FROM LIBBY NORTH AND
ESPECIALLY NEAR THE CANADIAN BORDER...MAINTAINING A LEVEL IN WHICH
THE PRECIPITATION TYPE APPEARS TO BE A WET SNOWFALL. THE
VISIBILITY SENSOR AT LIBBY HAS STEADILY BEEN REGISTERING NEAR 1
MILE OR LESS MOST OF THE NIGHT AND GIVEN THE PRECIPITATION
INTENSITY SHOWN BY AREA GAGES...BELIEVE SNOW IS FALLING IN LIBBY
THIS MORNING. THE MORNING COMMUTE COULD BE PARTICULARLY
CHALLENGING DUE TO THE SLUSHY NATURE OF THE SNOWFALL. ANOTHER GOOD
BURST OF FLUFFIER...BETTER ACCUMULATING SNOW IS EXPECTED WITH THE
COLD FRONT LATER TODAY.
IN GLACIER NATIONAL PARK PRECIPITATION IS CURRENTLY FALLING AS A
RAIN/SNOW MIX OR PERHAPS A WET...POORLY ACCUMULATING SNOW. THIS
MAKES SENSE DUE TO THE STEADY WARMING OBSERVED IN THE HIGHER
TERRAIN OVERNIGHT WHICH HAS DRAMATICALLY REDUCED THE SNOW/WATER
RATIO. HOWEVER IMPACT WORTHY SNOW WILL LIKELY OCCUR AS THE DAY
PROGRESSES AND TEMPERATURES ALOFT FALL WITH THE FRONTAL PASSAGE
THIS MORNING. AROUND 2 TO 5 INCHES OF TOTAL ACCUMULATION ARE
EXPECTED THROUGH LATE THIS AFTERNOON.
ELSEWHERE WINTER WEATHER HIGHLIGHTS FOR LOOKOUT AND LOLO PASS AS
WELL AS MUCH OF CENTRAL IDAHO WILL CONTINUE UNCHANGED. GENERALLY
SPEAKING...7 TO 12 INCHES OF TOTAL SNOWFALL ARE STILL EXPECTED AT
PASS LEVEL AND ACROSS THE SURROUNDING MOUNTAINS. LOST TRAIL PASS
WILL LIKELY RECEIVE 2 TO 5 INCHES OF NEW SNOWFALL WITH THIS
SYSTEM. TRAVEL OVER MOUNTAIN ROADS AND PASSES WILL BE IMPACTED BY
SNOW AND BLOWING SNOWFALL TODAY.
TONIGHT PRECIPITATION WILL DECREASE ACROSS MUCH OF NORTHWEST
MONTANA WITH ONLY SCATTERED SHOWERS REMAINING. HOWEVER SOME MODELS
DO SUGGEST THAT ANOTHER SHOT OF SNOW MAY BE POSSIBLE OVER THE
CENTRAL IDAHO MOUNTAINS AND PERHAPS LOST TRAIL PASS WEDNESDAY
MORNING.
THE MODELS ARE IN AGREEMENT THAT WARM SOUTHWESTERLY FLOW WILL
PERSIST OVER THE NORTHERN ROCKIES THROUGH AT LEAST SATURDAY. A
PLUME OF MOISTURE IS ANTICIPATED TO SWING THROUGH THE REGION ON
THURSDAY AFTERNOON/EVENING TIME FRAME WHICH COULD CAUSE
SIGNIFICANT PRECIPITATION ACROSS THE REGION. THE SNOW LEVELS
APPEAR TO REMAIN FAIRLY HIGH SO ONLY THE HIGHER TERRAIN AND
MOUNTAIN PASSES ARE ANTICIPATED TO RECEIVED DECENT SNOW
ACCUMULATIONS WHILE THE VALLEYS SHOULD RECEIVE PREDOMINATELY RAIN
FROM THIS FEATURE. THE STEADY PRECIPITATION COULD LINGER INTO THE
FRIDAY AFTERNOON. THE MODELS DIVERGE SLIGHTLY ON THE TIMING OF THE
TROUGH OF LOW PRESSURE MOVING ONTO THE WEST COAST. THE DEPTH AND
TIMING OF THIS TROUGH WILL IMPACT SNOW LEVELS AND THE AMOUNT OF
MOISTURE STREAMING INTO THE REGION THIS WEEKEND AND ON INTO NEXT
WEEK.
&&
.AVIATION...ANOTHER PACIFIC STORM SYSTEM WILL IMPACT NORTHERN
ROCKIES AIR TERMINALS DURING THE NEXT 24 HOURS AND BEYOND. THE
PRINCIPLE IMPACT TO AVIATION DURING THIS TIME WILL BE WITH
SOUTHWEST WINDS GUSTING OVER 35 KTS AFTER 13/1800Z AT
KMSO...KSMN...AND KBTM. WINDS WILL SUBSIDE AROUND 14/0300Z...
FOLLOWING A SURFACE COLD FRONT TO SWEEP ACROSS THE NORTHERN
ROCKIES FROM WEST TO EAST. A SECONDARY IMPACT TO AVIATION WILL BE
OCCASIONAL RAIN/SNOW SHOWERS LOWERING CEILINGS. TERRAIN FEATURES
WILL BE OBSCURED AT TIMES DUE TO PRECIPITATION AND LOW CLOUDS AS
WELL.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY FROM 9 AM THIS MORNING TO 9 PM MDT THIS EVENING
BUTTE/BLACKFOOT REGION.
WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 9 AM MDT
WEDNESDAY ABOVE 3000 FEET FOR THE BITTERROOT/SAPPHIRE
MOUNTAINS.
WIND ADVISORY FROM 9 AM THIS MORNING TO 6 PM MDT THIS EVENING
FLATHEAD/MISSION VALLEYS...MISSOULA/BITTERROOT VALLEYS...
POTOMAC/SEELEY LAKE REGION.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR I-90
LOOKOUT PASS TO HAUGAN.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING WEST GLACIER
REGION.
WINTER WEATHER ADVISORY UNTIL 3 PM MDT THIS AFTERNOON ABOVE 2500
FEET FOR THE KOOTENAI/CABINET REGION.
ID...WIND ADVISORY FROM 9 AM THIS MORNING TO 9 PM MDT THIS EVENING
EASTERN LEMHI COUNTY...WESTERN LEMHI COUNTY.
WINTER WEATHER ADVISORY FROM 8 AM THIS MORNING TO 8 AM PDT
WEDNESDAY ABOVE 3000 FEET FOR THE SOUTHERN CLEARWATER
MOUNTAINS.
HIGH WIND WARNING UNTIL 2 PM PDT THIS AFTERNOON FOR GRANGEVILLE
AND VICINITY.
WIND ADVISORY UNTIL 2 PM PDT THIS AFTERNOON LOWER HELLS
CANYON/SALMON RIVER REGION...NORTHERN CLEARWATER MOUNTAINS.
&&
SHORT TERM...DICKERSON
LONG TERM....SMITH
AVIATION...DICKERSON/KITTSMILLERThe national radar mosaic for the moment the first event began.
2 high wind, 2 heavy snow. Local standard time, as filed.
The observation equipment 4 miles south of Grangeville measured a gust at 65 mph.
Heavy snow fell for 45 minutes 1 mile northwest of Grangeville with an accumulation of 1.5 inches, visibilities were 900 feet at 1045 am pdt.
Heavy snow was reported southwest of Grangeville, a trained spotter measured 3.5 inches in 3 hours.
The RAWS site at Kriley creek recorded a wind gust to 73 mph at 5200 feet.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2012Every state in 2012This day in weather historyWarnings in Idaho, March 2012
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: 369685, 369686, 369687, 369688.