1 tornado, as filed by the National Weather Service.
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 national radar mosaic for the moment the first event began.
1 tornado. Local standard time, as filed.
Eyewitnesses reported seeing a funnel cloud pass over Roundup, and a tornado touchdown north of US12 1 mile east of Roundup. Several trees were downed, a chicken shed was demolished and several sections of wood fencing were destroyed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 1999Every state in 1999This day in weather historyThe tornado archive for Montana, 1999Warnings in Montana, May 1999
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: 5694537.