A cold front and upper elvel disturbance moved over the Northern Rockies. These combined to create deep instability over the region.
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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.
A cold front and upper elvel disturbance moved over the Northern Rockies. These combined to create deep instability over 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 Jul 22, 9:20 AM MST, 57 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 1020 AM MDT FRI JUL 22 2011 .UPDATE...ADJUSTED CHANCES OF PRECIPITATION FOR THE REST OF THE DAY. && .DISCUSSION...COLD FRONT HAS SHIFTED EAST OF THE CONTINENTAL DIVIDE THIS HOUR WITH ISOLATED SHOWERS LEFT IN ITS WAKE. THE UPPER LEVEL TROUGH STILL LINGERS ALONG THE MONTANA/CANADIAN BORDER AND WILL KEEP ENOUGH COLD AIR ALOFT FOR INSTABILITY SHOWERS TO LINGER OVER NORTHWEST MONTANA AND THE CONTINENTAL DIVIDE. WITH AN INCREASED SURFACE PRESSURE GRADIENT OVER LEMHI COUNTY AND INCREASED INSTABILITY FROM COLD AIR ALOFT...EXPECT TO SEE SOME WINDY CONDITIONS THIS AFTERNOON. CURRENT FORECAST HAS BREEZY WINDS IN THE VALLEYS WITH LOCALLY WINDY CONDITIONS IN THE HIGHER TERRAIN. WILL MONITOR THE VALLEY WINDS AND IF THE HIGHER TERRAIN WINDS MIX DOWN...ANOTHER UPDATE WILL BE NECESSARY. && .AVIATION...A COLD FRONT IS EXITING THE REGION TO THE EAST LATE THIS MORNING AND LEAVING A FEW LINGERING SHOWERS BEHIND. CEILINGS WILL GRADUALLY RISE THROUGH THE MORNING AND EARLY AFTERNOON. WINDS WILL INCREASE THIS AFTERNOON WITH GUSTS TO 25 KNOTS. SKIES WILL QUICKLY CLEAR OUT THIS AFTERNOON AND WINDS WILL DIE DOWN THIS EVENING. MOSTLY CLEAR SKIES AND LIGHT WINDS WILL PREVAIL EARLY THIS WEEKEND. && .PREV DISCUSSION... /ISSUED 338 AM MDT FRI JUL 22 2011/ DISCUSSION...THE WELL ADVERTISED COLD FRONT HAS ARRIVE TO THE NORTHERN ROCKIES THIS MORNING AND HAS PASSED THROUGH MUCH OF NORTHWEST MONTANA AND IS CURRENTLY PASSING THROUGH MISSOULA. THIS COLD FRONT WILL CONTINUE THROUGH THE REST OF THE REGION THIS MORNING AND THERE IS ENOUGH INSTABILITY FOR ISOLATED THUNDERSTORMS AND IN FACT LIGHTNING STRIKES ARE BRING OBSERVED ALONG THE NORTHERN BORDER OF IDAHO AND MONTANA. THE CLEARWATERS IN IDAHO AND THROUGH NORTHWEST MONTANA HAVE A MOIST PROFILE THAT WILL TRANSLATE INTO THE MAIN FOCUS FOR RAIN THIS MORNING. A CIRCULATION PASSING THROUGH EASTERN WASHINGTON CONTAINING UPPER LEVEL INSTABILITY WILL ALSO PASS THROUGH NORTHWEST MONTANA THIS MORNING AND IS EXPECTED TO PRODUCE MANY TENTHS OF INCHES OF MOISTURE. THUNDERSTORMS WITHIN THIS CIRCULATION WILL LIKELY PRODUCE PERIODS OF MODERATE TO HEAVY RAIN AND LOCATIONS BENEATH THESE CELLS HAVE A CHANCE FOR EVEN MORE RAIN ACCUMULATION. RAIN WILL LIKELY LINGER IN FAR NORTHWEST MONTANA AND GLACIER NATIONAL PARK THROUGH THE AFTERNOON. ONCE THE COLD FRONT PASSES THROUGH IDAHO AND WESTERN MONTANA...WHICH FOR THE MOST PART WILL OCCUR BY LATE THIS MORNING...MUCH DRIER AIR WILL FOLLOW WITH GUSTY WEST WINDS EXPECTED. LEMHI COUNTY IDAHO AND ALONG THE DIVIDE WILL EXPERIENCE THE STRONGEST WINDS THIS AFTERNOON THROUGH THIS EVENING. FLATHEAD LAKE WILL ALSO EXPERIENCE GUSTY WINDS THAT WILL CREATE LARGE WAVES AND CHOPPY WATER. THESE WINDS WILL RELAX BY LATE EVENING AND COOL OVERNIGHT TEMPERATURES ARE EXPECTED TONIGHT UNDER THE DRY AIRMASS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION STARTING SATURDAY. TEMPERATURES WILL QUICKLY REBOUND TO NEAR NORMAL SATURDAY AND BACK TO THE UPPER 80S AND 90S ON SUNDAY AND MONDAY. ANOTHER SHORTWAVE IS POSSIBLE LATE IN THE DAY ON MONDAY WITH A RETURN TO THUNDERSTORM CHANCES. BELOW NORMAL TEMPERATURES WILL FOLLOW FOR THE REST OF THE WEEK. && NOTE: FLOOD WATCHES...WARNINGS AND ADVISORIES WILL NOT BE LISTED BELOW. .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && UPDATE...MEAD PREVIOUS DISCUSSION....KITSMILLER AVIATION...LEACH
The Missoula radar (KMSX), 127 km away, was scanning. The volume nearest the first event began at 17:19 UTC.
1 funnel cloud. Local standard time, as filed.
The public reported a cold air funnel cloud near Creston. In addition they received 0.45 inch of rain in 23 minutes along with some hail.
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, July 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: 331369.