On a broader scale, Rapid City is in the upper Midwest, downstream from the Rocky Mountains. The general topographic slope is downward from west to east. I decide to start with the current US surface map. If the weather pattern moves east as usual, there will be a major change in the weather in store for Rapid City. Instead of the present southerlies, the wind will shift to the north or west and they will be getting a blast from the north.
Tomorrow ought to be much colder than today.
I say that not just because of the northwest winds, but also because of the thickness pattern. Take another look at the 4-panel map. Notice that the thicknesses drop over Rapid City during the period. That means the airmass is getting colder. This is called cold advection.