If the earth's rotation slowed down, how would that affect the winds in the US?
Start with understanding what makes our air currents work the way they do when the Earth is rotating normally. Pay attention to temperature and rotational affects.
Then try to find out how these factors that govern air currents change as the Earth slows down.
Lastly, given what you've found out from the last two statements, predict how air currents would act when the Earth's rotation is slowed.