Tue Dec 7 2021: A clipper system continues to pivot across southern Minnesota this afternoon yielding some snow observations of up to 5â?? of fluffy snow. The falling precipitation and saturation has cleaned out the PM25 as expected leaving Green (Good) across the entire state. Further north following the clipper the surface winds have become light and variable with winds generally in the WSW at or below 5mph. This has allowed PM values to creep up to the upper levels of Green (Good). Overnight winds will go calm and that trend will continue Wednesday. Therefore have increased the forecast to Yellow (Moderate) for the Twin Cities metro as well as Moorhead where it appears that winds will be light enough to allow for some stagnation and local concentration of PM will creep up. Elsewhere Green (Good) is forecasted. A similar story for Thursday where winds take on a southerly component but still remain largely 5mph or less through the mixing layer. Lower-level Yellow (Moderate) is again forecasted in the Twin Cities area as well as Moorhead with Green (Good) elsewhere. Friday the next storm system approaches and will bring with it the risk for snow as well as keep conditions in the Green (Good) condition.