From time to time, especially during the spring months, you'll hear meteorologists talk about "Backdoor Cold Fronts" and the impact they may have on the forecast. A backdoor cold front is simply a cold front that moves south or southwest along the Atlantic seaboard and Great Lakes...most frequently during the spring. Winds behind these backdoor fronts switch east or northeast off the cooler waters of the Atlantic. These differ from a "typical" cold front, which generally move west to east across the region, with west or northwest winds behind them. They can sometimes stall out over an area, leading to a stark difference in temperature. During the spring months, these backdoor fronts can drop temperatures by more than 20 degrees in just a few hours, as their momentum is aided by the cold, maritime air-mass present over the still chilly North Atlantic waters.
Here is an example of a backdoor front that occurred and its' progression. On Day 1, the front began to advance into New England late in the day, helping to increase cloud cover and lower temperatures slightly into the 70s from Boston to Worcester, MA. Winds turn out of the east-northeast, bringing cooler, maritime air off the relatively cold Atlantic Ocean. In fact, with the clouds and drizzle around by Day 2, temperatures struggled to even reach 50° in Boston, which was nearly 30 degrees colder than what occurred a few days earlier when highs neared 80°. Worcester also set a record "low-maximum" in this case on Day 2 when the high temperature only approached 47°. After the frontal passage, temperatures fell more than 20 degrees in New York City, from a high of 86° on Day 1 to only 64° on Day 2.
By Day 3, the backdoor front pushed rather far to the west before stalling out along the Appalachian Mountains from Western New York to Western Virginia. Backdoor cold fronts are generally "shallow" in nature, with much of the colder, maritime air only extending a few thousand feet above the surface and therefore often have a very difficult time passing over the mountains. Day 3 also saw some of the coolest temperatures and thickest cloud cover along, and just to the east of the front, with most of New England actually drying out as an area of high pressure built in from the northeast. Between Days 2 and 3, high temperatures dropped from 83 to 59° at Harrisburg, PA and from 88 down to 62° in Washington, DC.
Now, backdoor fronts don't always extend this far west, as they can easily stick around parts of the Mid-Atlantic before pushing back east. Still, they are tricky to forecast and can be the difference between a sunny, warm spring day in the 70s to 80s vs a cool and damp 50s and 60s under lots of cloud cover. Our WeatherWorks Meteorologists recognize these patterns and adjust forecasts for these potential swings in temperature and potential wet weather that can affect sensitive outdoor operations. If you've had your work operations hampered by a backdoor cold front, might be time to switch your weather provider. Email us at info@weatherworksinc.com or call 908-850-8600 to see if a WeatherWorks forecast is right for you.
