This animation of the GOES-8 fog/stratus product covers the period 03:15 to 07:32 UTC on 05 March 2001 [9:15 PM CST on 04 March to 01:32 AM CST on 05 March]; there was a data gap between 04:02 and 06:45 UTC due to spring eclipse radio frequency interference. The fog/stratus product is a difference of the 3.9 micrometer and 10.7 micrometer InfraRed (IR) brightness temperatures, with fog/stratus features having temperature difference values of about -1 to -6 degrees K (yellow to red enhancement). Surface weather and cloud ceiling [feet above ground level] are also plotted on the fog/stratus product imagery.
The large area of fog/stratus over much of central South Dakota, southwestern North Dakota, and northeastern Montana was nearly stationary, while a second area of elevated stratus was moving westward across Minnesota into eastern North Dakota and extreme northeastern South Dakota. Another narrow fog/stratus feature can be seen developing within the James River valley region of east-central South Dakota.
The feature moving westward into eastern North Dakota and extreme northeastern South Dakota was a relatively shallow (as suggested by brightness temperature difference values of only 1-3 K, yellow to orange enhancement) deck of elevated stratus (no fog reports on the ground) with cloud bases 2500-3500 feet. The larger feature aross much of central South Dakota, southwestern North Dakota, and northeastern Montana was thicker (as suggested by the greater brightness temperature difference values of -4 to -5 C, red enhancement), with fog/freezing fog being reported at several locations and cloud bases at or below 1000 feet.