Today, a strong high pressure will build over the western half of the U.S. and stick around for the remainder of the week. High pressure is usually associated with clear skies and calm conditions, and that's exactly what will happen. Today, the region will have clear skies and calm/quiet conditions into the beginning of next week. The highs will range between the 30s and low 50s. Tomorrow and Friday, portions of north-central and eastern Montana will be slightly breezy at times, but as high-pressure camps out and strengthen, inversions will develop in the valleys. During an inversion, cold air will stay trapped beneath warm air, creating a pocket of stagnant air in the valleys; another thing to keep in mind during an inversion low lying clouds and fog will develop, and the air quality will begin to deteriorate.
Have a great day,