A very strong high pressure system has been building off the Pacific coast and is slowly making its way inland. We will be on the northeast side of the clockwise rotation, meaning we will have moist northwest flow bringing partly to mostly cloudy skies to the area through Wednesday.
Today, expect partly to mostly cloudy skies as high temperatures range from the upper 20s to mid 30s. As the center of the high pressure system slowly progresses closer to western Montana Wednesday and Thursday, we will see a stagnant weather pattern set up.
Winds will be very calm area-wide from the second half of the week through the weekend. Valley inversions will set up, especially west of the divide. This will cause dense fog and low-level stratus cloud development. High temperatures will stay in the 20s during this time.
During this time in southwest Montana, sunny skies will be dominant as high temperatures reach the 30s and lows fall into the 10s.
Some models are indicating the high pressure system will begin to breakdown from Sunday into Monday. Being 5 to 6 days out, we will continue tracking this development and update you when details become clearer.