Watch the Back Door
We recently wrote about one type of cold front known as ANA which arrived amid sound and fury, and departed with accumulating snow in its wake. The remarkably warm air which we have enjoyed over the weekend is about to be replaced by a completely different sort of front. This one arrives not from the usual westerly direction but instead will run down quietly from the Northeast.
The typical scenario is that cold air is racing around a low pressure system to our north as the air moves in a counterclockwise direction. As it approaches our area we see it as a southwest flow, and when the front passes it blows from the northwest. But cooler air can still circulate around a high pressure system — in a clockwise direction. As this high pressure to our northeast slides a bit further south, the cooler air will invade, and drop temperatures dramatically with a wind shift to the Northeast. Another difference is that there is typically no moisture or thunderstorms associated with this type of front and, they are called “dry fronts."
Of course, nothing is constant in weather and in a few days the boundary between the two air masses will cross our region again going in the opposite direction, bringing back warm air once more.