On May 3, a deep and cold low pressure trough moved over the Northern Rockies bringing very heavy snow to the higher elevations of Southwest Montana.
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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.
On May 3, a deep and cold low pressure trough moved over the Northern Rockies bringing very heavy snow to the higher elevations of Southwest 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 May 3, 3:02 AM MST, 1 hour 58 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
402 AM MDT THU MAY 3 2007
.DISCUSSION...A VERY MOIST UPPER LEVEL SYSTEM AND ASSOCIATED COLD
FRONT WILL CONTINUE TO AFFECT THE NORTHERN ROCKIES TODAY. A LARGE
SWATH OF PRECIPITATION HAS FORMED JUST AHEAD OF THIS FRONT...WHICH
IS CURRENTLY LOCATED JUST EAST OF MISSOULA. AS THE FRONT
PASSES...SNOW LEVELS WILL DROP DRAMATICALLY TO AROUND 4000 FEET.
THEREFORE...SOME ACCUMULATING SNOW IS EXPECTED DOWN TO THE HIGHER
VALLEY LOCATIONS OF SOUTHWEST MONTANA WITH HEAVIER AMOUNTS IN THE
HIGHER TERRAIN. LUCKILY...FORECAST MODELS SHOW A QUICK PROGRESSION
OF THE BEST FORCING OUT OF THE REGION BY THIS AFTERNOON...SO HAVE
OPTED TO GO WITH SNOW ADVISORY OVER A WARNING FOR THE
BUTTE/BLACKFOOT...POTOMAC/SEELEY LAKE AND SAPPHIRE MOUNTAINS. A
LITTLE CONCERNED WITH SNOWFALL AMOUNTS IN GLACIER PARK AS MODELS
CONTINUE TO PAINT COPIOUS AMOUNTS OF PRECIPITATION OVER THE AREA.
HAVE DECIDED TO LEAVE THIS REGION OUT OF THE ADVISORIES HOWEVER AS
IT SEEMS THAT COLDEST AIR WILL NOT MAKE IT INTO THE PARK UNTIL
AFTER THE HEAVIEST PRECIPITATION...CONFINING MOST THE SNOWFALL
ABOVE IMPACT AREAS.
THURSDAY NIGHT AND FRIDAY...THE NORTHERN ROCKIES WILL CONTINUE TO
BE INFLUENCED BY THE UPPER LEVEL TROUGH AS IT SLOWLY PUSHES
EASTWARD. THEREFORE...SHOWERY AND COOLER CONDITIONS ARE EXPECTED
TO PERSIST.
FRIDAY NIGHT THROUGH THURSDAY...A FEW SHOWERS ARE EXPECTED TO
LINGER ALONG THE CONTINENTAL DIVIDE THROUGH SATURDAY AS THE
TROUGH OF LOW PRESSURE SLOWLY MOVES OFF TO THE EAST. THE MODELS
HAVE COME IN LINE WITH A RIDGE OF HIGH PRESSURE BUILDING OVER THE
PACIFIC NORTHWEST THROUGH THE WEEKEND. THIS RIDGE WILL CAUSE A
WARMING AND DRYING TREND FOR THE NORTHERN ROCKIES. TEMPERATURES
APPEAR TO BECOME WELL ABOVE NORMAL BY MONDAY. THE MODELS BEGIN TO
DIVERGE FROM A SOLUTION FOR NEXT WEEK. THE LATEST RUN OF THE GFS
IS INDICATING THAT A SYSTEM WILL KNOCK THE RIDGE DOWN PUTTING THE
REGION IN ZONAL (WESTERLY) FLOW. THIS FLOW HAS THE POTENTIAL TO
BRING IN ENOUGH MOISTURE TO CAUSE SHOWER ACTIVITY. WHILE THE ECMWF
WANTS TO HOLD ON TO THE RIDGE FOR THE REMAINDER THE WEEK. AT THIS
TIME HAVE DECIDED TO MAKE MINOR CHANGES TO THE FORECAST AFTER
MONDAY.
&&
.AVIATION...A MOIST UPPER LEVEL SYSTEM WILL PLAGUE WESTERN MONTANA
AND NORTH CENTRAL IDAHO WITH WIDESPREAD RAIN AND SNOW SHOWERS
THROUGH THE DAY. HEAVIEST PRECIPITATION IS EXPECTED ACROSS SOUTHWEST
MONTANA AND ALONG THE CONTINENTAL DIVIDE...MAINLY AFFECTING
TERMINALS KMSO AND KBTM. WITH THIS PRECIPITATION...LOWERED CEILINGS
AND VISIBILITIES WILL OBSCURE MOUNTAINS AND PASSES. PLEASE SEE
APPROPRIATE TAFS AND TWEBS.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...SNOW ADVISORY UNTIL NOON MDT TODAY FOR BITTERROOT/SAPPHIRE
MOUNTAINS-BUTTE/BLACKFOOT REGION-POTOMAC/SEELEY LAKE REGION.
ID...NONE.
&&
SHORT TERM...VIA
LONG TERM....SMITH
AVIATION...VIAThe national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
Heavy snow was reported across southwest Montana, mainly during the morning hours. Snowfall ranged from 6 inches south Butte to 14 inches|around Georgetown Lake. I-90 over Homestake Pass was temporarily closed due to heavy snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2007Every state in 2007This day in weather historyWarnings in Montana, May 2007
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: 25294.