According to the HMS, there are concentrated areas of small fires burning in the Plains and Southeast States (top left). Consistent with this weekend, widespread Moderate (Code Yellow) AQI conditions were reached in the Plains, MS Valley, Great Lakes, Mid-Atlantic and Northeast states (top right). Portions of Vermont, eastern Pennsylvania, and along the border of Illinois/Indiana peaked at Unhealthy for Sensitive Groups (Code Orange) PM2.5 this morning, before subsiding by late afternoon. A quiet, stable weather regime for the eastern half of the U.S. continues, however conditions will become more unsettled by mid-week, when a cold front swoops through the Great Lakes. This evenings 6pm CST national surface weather map illustrates widespread high pressure conditions across the east (1024 pressure contour), as well as completely overcast sky cover (blue circles)(bottom left, courtesy SPC). Unfortunately the swath of clouds obscure today's MODIS Terra AOD measurements in this region (bottom right).