DiscussionDiscussion Last Updated: 02-24-2015 4:23:35 pm MST
A regime shift from a stagnant west coast ridge to a penetrating northwesterly storm track is underway. This progressive trough cycle is expected to persist through the beginning of March. Long-term models are calling for a return to high pressure mid-March. At this point, extensive periods of surface warming and increasing daylight hours make another persistent inversion event unlikely through the end 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.