Upper disturbance moves eastward across the region, with a weak surface cold front moving eastward along and just ahead of the upper disturbance. Additionally, a northwest-southeast trough over north-central Montana serves as an additional focus of lift.
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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 TFX wrote it up.
Upper disturbance moves eastward across the region, with a weak surface cold front moving eastward along and just ahead of the upper disturbance. Additionally, a northwest-southeast trough over north-central Montana serves as an additional focus of lift. Both surface boundaries result in low-level moisture convergence, but mainly focusing the best surface moisture across the north-central, central, and northeastern parts of the CWA. As a result, while showers possible just about anywhere in the CWA, the best chance for thunderstorms is mainly east of a line from Cut Bank to Fort Benton to Kings Hill Pass. With surface-based CAPE forecast over 1000 J/kg in most models, and mixed layer CAPE likely approaching if not exceeding 1000 J/kg, especially over Hill, Blaine, and NE'rn Chouteau, vigorous convection is possible. However, shear is minimal, with NW-W'ly winds of 10-25kts through the whole column, so storms are forecast to be very short-lived and/or 'pulse-y'. Some half-inch hail and gusty winds certainly possible. Severe hail or wind is not forecast. Showers and thunderstorms linger across north-central Montana through midnight, then die off overnight.
The Great Falls radar (KTFX), 171 km away, was scanning. The volume nearest the first event began at 21:59 UTC.
1 hail. Local standard time, as filed.
Half to one inch diameter hail reported. Minor street flooding and 53 mph wind gust also observed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2020Every state in 2020This day in weather historyWarnings in Montana, June 2020
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: 906269.