Pneumonia and Backdoor Fronts This Week

While amazing warmth continues over much of the eastern two-thirds of the nation this week, there are a couple of chilly pockets worthy of note.

The first is a strong lake breeze that is forecast to impact Chicagoland later today, after temperatures climb to record high levels.

This front is referred to as locals as a pneumonia front. Folks can get caught wearing short sleeves and no jacket as much colder air moves in. While the day starts warm, temperatures can plunge 20 to 40 degrees with a shift of the wind off the lake.

In New England, a phenomenon known as a backdoor front made southward progress Wednesday and has reached into the New York City area, New Jersey and part of the Delaware Valley today.

The satellite photo taken at midday Thursday tells the story. Low clouds in the wake of the back door front mark New England and part of the coastal mid-Atlantic.

This weekend, a second back door front will attempt to seep as far south as eastern North Carolina.

In Boston, temperatures hovered in the middle 40s Wednesday, after soaring into the 70s Monday and Tuesday. In portions of Maine, snow and freezing rain were occurring only a day after record highs occurred.

Which side of the front you are on today will determine whether you have temperatures reaching the 70s to near 80 or struggling in the 40 and 50s.

While the Great Lakes and Atlantic Ocean water temperatures are above normal this season, they still represent a chilly source of air. So in the early spring near a body of water, it is more a matter of which way the wind is blowing to determine how warm a location will be.