Earlier in January there was a thaw that ate all the snow that had filled the bee yard. January thaws can be very useful to the bees since a period of warm weather allows them to fly outside of the hive and make cleansing flights where they void all of the waste that they have retained rather than voiding inside their hives. The waste should be yellow. Dark brown is indicative of the disease, Nosema, which is essentially bee diarrhea.
My mother had checked on the hives at that time and reported that bees were coming out of all of the hives and making cleansing flights and painting the remaining snow yellow.
By th e time of this visit to the beeyard, Winter had returned an a light layer of snow as on the ground. The hives seemed to be in good shape. I did clean up the dead bees that had collected at the lower entrances. Purple and DarkGreen had the most to clean up. This will be something to keep an eye on, but not necessarily a sign of impending doom.