A strong thunderstorm developed over Lemhi County and brought severe hail to North Fork.
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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 strong thunderstorm developed over Lemhi County and brought severe hail to North Fork.
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 26, 1:41 PM MST, 28 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 241 PM MDT Sat May 26 2018 .DISCUSSION...Another afternoon of showers and thunderstorms is underway. This activity will be most focused over southwest Montana into Lemhi County and to a lesser extent northwest Montana the rest of the afternoon into the evening hours. One concern will be for flash flooding of small streams and creeks due to locally heavy downpours. Another concern is the potential of isolated severe thunderstorms with gusty winds over 50 mph and hail, primarily south of a line from southeastern Idaho County northeastward to MacDonald Pass. Scattered showers and thunderstorms will continue Sunday into Monday but will be focused across southwest Montana into Lemhi County. Otherwise, expect pleasantly warm temperatures and mostly sunny skies. After a relatively dry Tuesday, a cold front is anticipated on Wednesday leading to some gusty winds and a return to showers/thunderstorms. A showery pattern will finish out next week as temperatures dip to seasonable levels. && .AVIATION...Thunderstorm activity is expanding across Lemhi County into southwest Montana which will likely impact KSMN and KBTM into the early evening hours. Brief heavy downpours will be common, along with the potential for gusty winds over 45 kt and hail. Remnant showers and isolated lightning strikes are also possible at KGPI and KMSO. Convective activity will diminish after sunset but scattered showers will continue across southwest Montana and Lemhi County overnight. Patchy morning fog is possible Sunday in areas where rain falls this evening. Scattered showers and thunderstorms are again expected Sunday afternoon, mainly focused once again in Lemhi County and southwest Montana. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Flood Watch through Sunday afternoon Flathead/Mission Valleys. ID...None. &&
Special Weather Statement National Weather Service Missoula MT 118 PM MDT SAT MAY 26 2018 IDZ009-262000- Western Lemhi County ID- 118 PM MDT SAT MAY 26 2018 ...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL LEMHI COUNTY UNTIL 200 PM MDT... At 117 PM MDT, Doppler radar was tracking a strong thunderstorm 30 miles northwest of Challis, moving north at 10 mph. Nickel size hail and wind gusts of 50 to 55 mph will be possible with this storm. Locations impacted include... Yellowjacket. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4479 11442 4482 11467 4507 11468 4503 11430 TIME...MOT...LOC 1917Z 189DEG 9KT 4489 11453
Special Weather Statement National Weather Service Missoula MT 231 PM MDT SAT MAY 26 2018 IDZ009-010-262115- Eastern Lemhi County ID-Western Lemhi County ID- 231 PM MDT SAT MAY 26 2018 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL LEMHI COUNTY UNTIL 315 PM MDT... At 229 PM MDT, Doppler radar was tracking a strong thunderstorm 14 miles west of Salmon, moving north at 10 mph. Nickel size hail and wind gusts up to 50 mph will be possible with this storm. Very heavy rain is also expected with this storm. Locations impacted include... Leesburg and Cobalt. LAT...LON 4503 11410 4509 11434 4534 11428 4525 11392 TIME...MOT...LOC 2029Z 200DEG 10KT 4513 11419
The Missoula radar (KMSX), 185 km away, was scanning. The volume nearest the first event began at 21:09 UTC.
1 hail. Local standard time, as filed.
Hail damaged skylights, air conditioning units and caused leaks in a few RV's at a nearby campground.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2018Every state in 2018This day in weather historyWarnings in Idaho, May 2018
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: 750401.