2021 started off with over 6 inches of snow in the Wichita area. This snow stuck around for several days which means that we needed to account for the snow on the ground when forecasting. If there is a significant amount of snow pack on the ground, it will release cooler air at the surface and cool the high temperatures for the day.
Additionally, rays from the sun that will usually reach the ground and warm surface temperatures, are hitting the snow instead. The snow will either absorb these rays or reflect it back into the atmosphere. That means that there is less warmth from the sun to increase afternoon temperatures.
Lastly, if a region to the south has a significant amount of snowpack and there is a southerly wind, and even though we often assume that southerly winds will help to warm temperatures, then that wind will bring the cooler air from the south to the northern communities and cool temperatures. This movement by the wind to change the temperature is a term that meteorologists call temperature advection.