Significant Cooldown Headed East This Week
September 17, 2012; 8:56 AM
Another strong cold front will be making inroads across the eastern two-thirds of the nation early this week, cutting daytime temperatures by more than 30 degrees in some areas.
Though waves of cool air have permeated the country over the past week, this significant cooldown is likely a sign of a pattern change that will lock in through at least the end of the month.
To end the weekend, the northern Plains and Upper Midwest felt the chillier air from Canada arriving along a brisk northerly wind in the wake of the front.
Temperatures well into the 80s to start the weekend on Saturday were replaced by 50s and 60s to finish it in cities such as Billings, Fargo and Winnipeg.
Similar changes will arrive today farther south and east from the Front Range of the Rockies to the western Great Lakes, including in the cities of Denver, Omaha and Minneapolis.
The rest of the Midwest, Ohio Valley and even a significant part of the interior Northeast will cool off on Tuesday.
Though the transition between air masses was meek on Sunday with just a few showers, some nasty thunderstorms are expected to erupt later today and again on Tuesday as some moisture and energy is added to the frontal system.
Severe storms with damaging wind gusts will be possible in Chicagoland and St. Louis come late this afternoon and early this evening.
A large part of the mid-Atlantic and Northeast will be downright wet and wild come Tuesday, with severe thunderstorms among the many expected threats in the big cities along the I-95 corridor.
In the wake of the transition, the air mass will make some shiver.
Temperatures for a couple of nights will be the coolest so far this season in most areas from the northern Plains to the East Coast. For some sheltered, normally colder areas, this could mean the season's first frost.
Chicago, St. Louis, Little Rock, Nashville, Indianapolis, Cincinnati and Boston are all forecast to experience their first morning with temperatures in the 40s since last spring this week.
The chilly air will have many thinking candy corn, pumpkins and changing leaves.
Autumn officially starts in the Northern Hemisphere on Saturday, Sept. 22 at 10:49 a.m. EDT.
Thumbnail image from Flickr user brixton.