Clouds hindered today's AOD retrievals, as shown in today's MODIS Terra RGB image. The clouds eastern United States are associated with the storm systems that brought snow to the Midwest and tornadoes to the South. The storm is expected to bring more than a foot of snow to New England and western Pennsylvania, as this region is under a Winter Storm Warning according to the National Weather Service. Clouds in western United States are associated with storm system that brought snow into the region yesterday and left behind cooler and unsettled weather. The National Weather Service issued a Hazardous Weather Outlook warning as freezing fog is expected over this region tomorrow. An Air Quality Action Day for PM2.5 for the seven-county Denver-Boulder metropolitan area. Residential Burning Restrictions and requests to limit driving are in effect until at least 4 PM (local time) Thursday, December 27, 2012. Shallow mixing, and light winds are causing poor visibility. PM2.5 AQI concentrations are forecasted to be Code Orange (Unhealthy for Sensitive Groups).