-40º temperatures in Minnesota
MODIS 11.0 µm IR and GOES-12 10.7 µm IR images
AWIPS images of the 1-km resolution MODIS 11.0 µm IR and the 4-km resolution GOES-12 10.7 µm IR channel data (above) showed that large portions of northwestern Minnesota and eastern North Dakota exhibited surface IR brightness temperatures colder than -40º F (-40º C) at 08:45 UTC (2:45 am local time) on 02 January 2010. In northwestern Minnesota, the coldest IR brightness temperature values on the MODIS image were -45º C, compared to -42º C on the GOES-12 image. Note the significantly warmer signature of the Minneapolis/St. Paul urban area, as well as the unfrozen waters of Lake Superior.
A map of the 24-hour minimum temperatures (below; courtesy of MesoWest) showed that 3 sites (Pokegama Lake Dam, Gatzke, and Debs) reported a low of -40º across northern Minnesota on the morning of 02 January.
24-hour minimum temperatures across northern Minnesota (courtesy of MesoWest)