A HIGH WIND WARNING is in effect for the Rocky Mountain Front into Tuesday afternoon.
A HIGH WIND WATCH has been issued for north-central Montana on the Hi-Line until Tuesday evening.
All good things must come to an end. The recent prolonged period of sunshine, mild temperatures and quiet weather is beginning to end. Clouds increasing on Monday were a sign of the high pressure breaking down. Tuesday will still be a mild day for most of the state, but clouds will once again work across the sky. Warm and windy conditions will once again be widespread across the plains. The valleys of western Montana including Helena will be inverted again with calm conditions and cooler temperatures. There likely will be a chinook arch cloud formation just east of the Continental Divide making for mostly cloudy skies there. Farther east, skies will be partly cloudy. Either way, the bluebird clear blue skies are gone. A weak low pressure trough will move through the state on Wednesday. A little light snow will break out off of the Rocky Mountain Front and out across north-central Montana through the afternoon and evening. Accumulation will be light, with 1-2" maximum. Many locations will not have any accumulation. Thursday and Friday will be quiet and seasonably cool. Another low pressure will move in this weekend with snow that will mainly be west of the Continental Divide. Although not much if any snow will fly east of the Divide, the storm activity is picking up heading into the second half of December.
Have a great day.