This animation of GOES-10 10.7 micrometer longwave InfraRed (IR) imagery covers the period 03:00 to 07:30 UTC on 05 March 2001 (8:00 PM MST on 04 March to 12:32 AM MST on 05 March). One large area of fog/stratus was nearly stationary across much of central South Dakota, southwestern North Dakota, and northeastern Montana, while a second area of fog/stratus was moving westward across Minnesota into eastern North Dakota and extreme northeastern South Dakota.
Portions of central/eastern North Dakota and eastern South Dakota which were not covered by the fog/stratus were experiencing strong radiative cooling due to the extensive snow pack (10-34 inches) and light winds, and surface temperatures were dropping into the single digits F (-13 to -17 C). Regions beneath the fog/stratus reported warmer surface temperatures, from the middle teens F to the middle 20s F (-3 to -8 C). The tops of the fog/stratus were actually warmer (-10 to -14 C, yellow enhancement) than the adjacent clear sky regions where radiational cooling was prevalent (-15 to -20 C, light blue enhancement).