A few thunderstorms have popped up Sunday afternoon across southwest Montana. Isolated lighting strikes and some gusty winds in the 30 mph range will continue for the late afternoon and early evening. Elsewhere, valley rain and high mountain snowfall will continue periodically into the night.
Overnight showers will become a mix of rain and snow above 4500 to 5000 feet with little to no accumulation expected for valleys at those higher elevations. Minor accumulations are possible around Big Sky, Bozeman Pass, Lost Trail pass, Marias Pass, and Lolo Pass. Road impacts should be minor. Valley temperatures Monday morning will sit in the mid 30s.
Conditions will be cool and showery on Monday with a mix of rain and sun. Morning showers in Butte and Bozeman will be either snow or a wintry mix. Computer models are hinting at a period of heavier snow for the areas surrounding Yellowstone Monday evening that would create some slushy and wet road conditions. Highs will be slightly cooler, in the low 50s with some only in the upper 40s.
This pattern of plentiful showers and snowfall at higher elevations continues through the week. Temperatures will bottom out in the mid to upper 40s Thursday afternoon with precipitation falling as snow most of the day above 5000 feet. We will see slightly less shower coverage and a slow warming trend Friday into next weekend.