A low- to mid-level disturbance over northwestern WY and vicinity during the early afternoon of May 17th reached northwestern SD and vicinity by early afternoon of the 18th. At that time, the disturbance exhibited a well-defined cyclonic circulation center over northwestern SD.
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 TFX wrote it up.
A low- to mid-level disturbance over northwestern WY and vicinity during the early afternoon of May 17th reached northwestern SD and vicinity by early afternoon of the 18th. At that time, the disturbance exhibited a well-defined cyclonic circulation center over northwestern SD. Isentropic lift accompanying this disturbance triggered periods of rain and mountain snow in north-central Montana on the 17th into the 18th. At lower elevations, rain mixed with or changed to wet snow on occasion during the late evening of the 17th through mid-morning of the 18th. This stemmed from unusually-cold air accompanying the system and the wet-bulb effect. Snowfall totals were generally no more than several inches with minimal impacts. However, significant and impactful snowfall occurred in vicinity of the Little Rockies in Blaine County.
1 heavy snow. Local standard time, as filed.
COOP observer reported 11.0-inches of storm-total snowfall and cars in the ditch while traveling through Lodge Pole. Post-event report. Exact duration of snowfall unknown.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2019Every state in 2019This day in weather historyWarnings in Montana, May 2019
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 2026-10-01. Each event’s entry at NCEI: 818938.