On May 12, a strong short wave trough moved northeast across the area. Strong surface based instability and unidirectional wind shear led to the development of a severe thunderstorm as the system interacted with a thermal trough that was positioned over the area.
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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 12, a strong short wave trough moved northeast across the area. Strong surface based instability and unidirectional wind shear led to the development of a severe thunderstorm as the system interacted with a thermal trough that was positioned over the area.
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 12, 5:17 PM MST, 5 hours 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 617 PM MDT SAT MAY 12 2007 .UPDATE...UPDATED THIS EVENING TO CANCEL THE SEVERE THUNDERSTORM WATCH WHICH WAS IN EFFECT FOR SOUTHWEST MONTANA WEST OF THE CONTINENTAL DIVIDE. ALTHOUGH SCATTERED THUNDERSTORMS WILL PERSIST INTO THIS EVENING...THE POTENTIAL FOR SEVERE STORMS WILL CONTINUE TO DWINDLE AS SURFACE HEATING BEGINS TO WANE WITH SUNSET. && .AVIATION...SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE EVENING HOURS...MAINLY CAUSING SOME LOWERED VISIBILITIES AND MOUNTAIN OBSCURATIONS. ADDITIONALLY...SOME GUSTY WINDS WILL ACCOMPANY STRONGER CELLS. PLEASE SEE APPROPRIATE TAFS AND TWEBS. && .PREV DISCUSSION... /ISSUED 313 PM MDT SAT MAY 12 2007/ DISCUSSION...SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR SOUTHWEST MONTANA THROUGH 10PM MDT THIS EVENING. SHORT WAVE ALONG THE WEST COAST. MOIST SOUTHWEST FLOW AHEAD OF THE FRONT HAS STARTED TO KICK OFF CONVECTION IN SOUTHWEST MONTANA AND CENTRAL IDAHO. THE ATMOSPHERE IS QUITE UNSTABLE ACROSS WEST CENTRAL MONTANA AND CENTRAL IDAHO WHERE THE FOCUS OF MOST THUNDERSTORM ACTIVITY WILL BE THIS EVENING. THE BEST DYNAMICS FOR POSSIBLE SEVERE WEATHER WILL BE IN SOUTHWEST MONTANA...WITH SOME STORMS POSSIBLY PRODUCING LARGE HAIL AND DAMAGING WINDS. THUNDERSTORMS SHOULD DECREASE IN INTENSITY AFTER LOSING HEATING OF THE DAY AT SUNSET. THE SHORT WAVE WILL APPROACH THE NORTHERN ROCKIES OVERNIGHT. DYNAMIC SUPPORT...MOISTURE AND INSTABILITY WILL PRODUCE SHOWERS OVERNIGHT. THE SHORT WAVE WILL MOVE SLOWLY ACROSS THE REGION ON SUNDAY AND CONTAIN ENOUGH DYNAMICS AND INSTABILITY FOR SOME ISOLATED THUNDERSTORMS. MONDAY THROUGH FRIDAY...THE TROUGH MOVES OFF TO THE EAST ON MONDAY...SOME LINGERING SHOWERS REMAIN MAINLY ACROSS THE EASTERN ZONES. A RIDGE REBUILDS OVER THE PACIFIC NORTHWEST TUESDAY THROUGH THURSDAY FOR MOSTLY SUNNY SKIES AND WARMING TEMPERATURES. ANOTHER APPROACHING TROUGH MOVES INTO THE PACIFIC NORTHWEST ON FRIDAY...TURNING THE UPPER LEVEL FLOW TO THE SOUTHWEST AND BRINGING MORE MOISTURE ALONG WITH AN UNSTABLE ATMOSPHERE. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && UPDATE...VIA PREVIOUS DISCUSSION....RPN/KOLATA AVIATION...CHURCH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MISSOULA MT 405 AM MDT SAT MAY 12 2007 IDZ005>009-MTZ005>007-043-122300- NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS- OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER REGION- WESTERN LEMHI COUNTY-MISSOULA/BITTERROOT VALLEYS- BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION- POTOMAC/SEELEY LAKE REGION- 405 AM MDT SAT MAY 12 2007 /305 AM PDT SAT MAY 12 2007/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL IDAHO AND WEST CENTRAL MONTANA. .DAY ONE...TODAY AND TONIGHT STRONG THUNDERSTORMS ARE EXPECT TO FORM LATE THIS AFTERNOON...PERSISTING INTO THE EVENING HOURS. SOME STORMS MAY CONTAIN STRONG WINDS AND SMALL HAIL. A FEW OF THE STORMS COULD BECOME SEVERE. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY EXPECT RAIN SHOWERS WITH A SLIGHT CHANCE FOR THUNDERSTORMS SUNDAY AS A COLDER PACIFIC WEATHER SYSTEM PASSES THROUGH THE REGION. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Missoula radar (KMSX), 149 km away, was scanning. The volume nearest the first event began at 05:57 UTC.
2 hail. Local standard time, as filed.
A member of the public reported nickel to quarter sized hail 2 miles west of Columbia Falls.
Columbia Falls Police called with a report that 0.75 inch diameter hail fell from the thunderstorm that passed through town.
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: 23698, 25301.