Instability and increasing flow aloft combined with an upper low and moisture over north central Oregon produced favorable conditions for severe thunderstorms across the northern Rockies. 75 inches in diameter.
Every event with a place to put it. 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.
Instability and increasing flow aloft combined with an upper low and moisture over north central Oregon produced favorable conditions for severe thunderstorms across the northern Rockies. The main threat with these storms was for large hail, ranging in size from 0.75 inches in diameter up to 1.75 inches in diameter. Heavy rain also accompanied these storms.
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 31, 1:57 AM PST, 4 hours 8 minutes earlier.
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</html>HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MISSOULA MT 134 AM MDT SAT JUL 31 2010 IDZ005>010-MTZ001>007-043-010000- NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS- OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER REGION- WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY-KOOTENAI/CABINET REGION- WEST GLACIER REGION-FLATHEAD/MISSION VALLEYS- LOWER CLARK FORK REGION-MISSOULA/BITTERROOT VALLEYS- BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION- POTOMAC/SEELEY LAKE REGION- 134 AM MDT SAT JUL 31 2010 /1234 AM PDT SAT JUL 31 2010/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL IDAHO...NORTHWEST MONTANA AND WEST CENTRAL MONTANA. .DAY ONE...TODAY THUNDERSTORMS WILL INCREASE IN COVERAGE AND INTENSITY ACROSS THE AREA THROUGH SATURDAY EVENING. SOME OF THESE STORMS MAY BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS POSSIBLE. THE GREATEST THREAT FOR SEVERE STORMS WILL BE DURING SATURDAY AFTERNOON AND EVENING. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER IS CURRENTLY EXPECTED. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. GIBSON
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</html>The Missoula radar (KMSX), 177 km away, was scanning. The volume nearest the first event began at 14:05 UTC.
4 hail, 1 thunderstorm wind. Local standard time, as filed.
A trained spotter reported several pine trees bent down/over with branches estimated at six inches in diameter broken off of trees from reported thunderstorm winds.
A trained spotter in Nez Perce reported one inch sized hail that fell for five minutes. Several trees have branches down, with diameters averaging one to one and a half inches.
A trained spotter reported golf ball sized hail with some larger pieces in the mix east of Kamiah.
Law enforcement reported golf ball sized hail in the Kamiah city limits.
Law enforcement reports golf ball sized hail in the Whitebird city limits.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2010Every state in 2010This day in weather historyWarnings in Idaho, July 2010
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 2026-09-30. Each event’s entry at NCEI: 252777, 252784, 252782, 252778, 252780.