It's impossible to explain weather changes in our area without talking about fronts, those blue and red snaking lines on weather maps. At the most basic level, a front is a boundary between warm and cold air. If the cold air is advancing on the warm air, the front is specifically called a cold front.

Most of the time, cold air - and thus cold fronts - approach our area from the Midwest or Great Lakes. But this time of year, chilly air can invade from another direction: the east or northeast off the still-chilly waters of the Atlantic Ocean. We call these wrong-way fronts "backdoor" cold fronts.

Often, temperatures ahead of a backdoor cold front are in the 70s or even 80s with southwest winds, but once the front moves through, winds swing around to the northeast and cool, cloudy Atlantic Ocean air takes over. So how would you know if a backdoor cold front went through? Well, if it's May, the sky will be filled with low clouds and chilly northeast winds will keep mid-afternoon temperatures in the 50s.