Inversion Forecast
Update 02/03/2025: Summary: Active weather remains the general weather pattern for the coming week and potentially beyond as the broad mean-state trough of low pressure continues to remain draped across the U.S. Extended range predictions have trended to a more favorable pattern for the western U.S. storm track. Although major storms remain elusive, at least a greater source region offers increased moisture availability for passing storm systems to produce better precipitation events than what the season has produced up to this point. Inversion risk for the short term and long term will remain very much suppressed as bare ground and warm air temps work against the late-stage inversion season. Short-term (Feb 3 - Feb 6): The work week weather pattern is predicted to preserve offshore storm systems and limit inversion conditions. The upstream trough is predicted to migrate onshore and through the western U.S. during the upcoming weekend, continuing to prevent inverted air profiles from taking root. Long-term: ( - mid February): Much of the first half of February's mean trough across Canada and resulting zonal-dominated flow for the contiguous U.S. remains the forecast. Such a weather pattern further limits inversion probability, although a few shortwave high pressure spells are likely to run through this pattern at times. IF snow cover is in place and the overriding airmass is cold enough, than inversion impacts would have a short time to return to Utah's valleys, however the predicted pattern and current landscape are both unfavorable for high-impact inversion conditions through the remainder of the inversion season.
This product is being developed by researchers at the Utah Climate Center. Using output from the National Center for Environmental Prediction’s (NCEP) Climate Forecast System (CFSv2), this technique projects surface inversion probability for persistent inversion events—defined as events lasting longer than 4 days—with a demonstrated “skill” over a span of ~ 30 days. A surface inversion probability of 35% or greater suggests a statistically significant likelihood of an extended event. It should also be noted that inversion forecasts, in and of themselves, are not air quality projections. The projection is valid for a radius of roughly 200 miles around Salt Lake City.
Image Interpretation: The blue bar graph shows the calculated Surface Inversion Probabilities. Values above the horizontal yellow line (~35% on the right axis) have a statistical significance of manifesting as persistent (> 4 days) inversion events. The solid black line above the SIP chart shows the ensemble average of 200mb geopotential heights for the most recent 16 CFSv2 forecasts. The individual dotted lines are individual model runs. The vertical red and yellow lines identify the initialization (+0) and 30 day (+30) locations. SIP values lying within this 30 day window have a statistically significant confidence interval. Values before the initialization data are obtained from NCEP reanalysis data.
For more information on the methodology and origins of this product, see the following publication here.