The Backdoor Cold Front
During the spring and summer months, you may hear the term backdoor cold front used by meteorologists in our area. Most cold fronts arrive from the northwest, but some come in from the northeast and they are the backdoor cold fronts. Every so often, a high pressure area will develop over New England or off the coast of the Northeast. Since winds blow clockwise around high pressure areas in the northern hemisphere, the wind will blow out of the northeast around the high pressure area. The air will pass over the chilly water off the coast of the Northeast and Northern Mid-Atlantic States. As this cooler air moves down the coast, it produces a cold front which can drop temperatures drastically due to the still cold water temperatures in the spring. Since the fronts come in from the northeast and not the northwest, the term žbackdoorÓ is used. Many a heat wave has been broken from these types of cold fronts. Temperatures can drop from the 90s to the 60s just like that. The ocean temperature will play a big role in what the temperature will drop to once the front moves through as the wind switches to the northeast. During the late summer, the back door cold fronts become less and less frequent. That is due to several factors, most notably the increase in water temperature and the weather patterns across the North American continent. Sometimes, back door cold fronts produce showers and thunderstorms, but they are not noted for producing widespread severe weather. They usually lack the dynamics in the upper atmosphere to produce severe weather. However, when it is very humid preceding the front, heavy rain can result from these fronts. Every so often, during the early spring, some sea fog will blow in after the passage of a backdoor cold front right along the coast. Low clouds from the ocean can penetrate inland several miles.