Knock knock knockin' on …the back door?
South wind everywhere, except where the wind has turned to the NE. Here's why:
Published Thursday, April 27, 2017 11:43AM ADT
Last Updated Thursday, April 27, 2017 12:01PM ADT
Every now and again, I see something on the maps and charts that is not at all common and I just blurt it out on air. That happened last evening while describing the unusual midweek weather pattern: the “backdoor cold front”.
After the words were out of my mouth I thought I should take a moment to explain…
I love the term because it describes the situation quite well: a front that is cold...and backing in!
You see, typically, a cold front approaches from the north or northwest. A back door cold front is a cold front that approaches from the east or northeast. The term is most commonly used here or in the northeast U.S. when cool Atlantic maritime air moves in from the east or northeast and replaces warmer continental air.
Right now, there’s a blocking high pressure system south of Labrador. The system responsible for our “liquid sunshine” is being blocked from any further west to east movement.
That low that is still south of Cape Cod and is being absorbed by a trough extending from a low over the central Great Lakes.
As it does so, the prevailing south wind is has started to come around to the northeast, pulling in some colder air. A noon, it’s 12 in Edmundston but only 3 in Bathurst. With a south wind, the temperature will climb to 15 in Edmundston today; with a NE wind, the temperature will hold near 3 or 4 over the Acadian Peninsula.
As the stalling high off the Avalon weakens, the cooler air will once again shift eastward, allowing for some heat to return to the NE corner of New Brunswick tomorrow.
There you have it, your new weather term for the day!