Inversion Forecast

Update 01/13/2025: Summary: Now firmly embedded in the historical heart of inversion season, a period of quiet weather ushers in cold conditions as inversions begin to populate the state's valleys, gathering momentum by midweek as the upstream ridge of high pressure migrates through the northern Rockies and places Utah into a stretch of favorable inversion conditions. An end-of-week visit by another round of anti-inversion storm activity offers a Friday/Saturday mixing opportunity before next week's significant polar outbreak threatens the contiguous U.S. with the coldest air of the season. Short-term (Jan 14 - Jan 18): Inversions will continue to gain a foothold across the state's usual inversion-prone areas, as minor snow cover, cold air, and a supportive weather pattern remains in place. Air quality is likely to degrade by Tues/Wed. and remain of moderate impact through at least Thursday, and potentially Friday, as the timing of the next storm system comes into focus. The Friday/Saturday storm system is currently forecast to be sufficiently strong to reset valley airsheds, sweeping away temperature inversions and pollution. Long-term: (Jan 19 - Late January): The extended period weather pattern forecast remains mostly favorable for inversion events, but as has often been the case this year, also keeps the door open for weak storm systems to pass through- resetting airsheds. The continual presence of the offshore ridge of high pressure looks to continue to keep Utah in its shadow, presenting scenarios of just enough eastward displacement at times to introduce impactful inversion events. On the other hand, the western U.S. storm track continues to be just close enough to Utah to preserve the chances for limited inversion impacts as well. As it stands right now, a larger impact inversion event is lining up to conclude the month of January, as the upstream ridge expands and strengthens. However, consistency and location uncertainty remains high, as a lack of sufficient eastward expansion would continue to allow weak storm systems to migrate through the region, ultimately limiting inversion impact severity. Attention right now is placed mostly on the evolution of next week's polar outbreak, and then the Pacific ridge's response in the wake of the cold surge of air into the continent.