After waves of cool air progress through the Midwest and Northeast this week, some areas will be cold enough for the first snow showers of the season by this weekend.
Temperatures have averaged 2-5 degrees Fahrenheit above average since early September from Minneapolis to Chicago, Cincinnati, Philadelphia, New York City and Boston.
The first push of cool air will be rather weak, but will erase above-average warmth from the Midwest to much of the East during the first part of the week.
A second push of cool air may cause temperatures to dip a bit more during the middle to latter part of the week.
The third push will be the most dramatic and can easily bring the coldest air of the season so far to the Great Lakes during Friday and Saturday and then the Northeast Saturday and Sunday. Showers will accompany the cold push. AccuWeather RealFeel® Temperatures around the Great Lakes will dip into the 30s. Leaf peepers and fans heading to ball games will need to dress warmly and may need a rain slicker.
"The pattern will generate a great deal of clouds, but it is possible that toward the tail end of the cold outbreak in the Midwest Saturday night and the Northeast Sunday night, when skies clear, that a frost or freeze could occur," AccuWeather Senior Meteorologist Dave Dombek said.
While the warm Great Lakes, as well as the Finger Lakes and other large water bodies will moderate the cold air somewhat, some places well away from the immediate lake, river and ocean shores can dip below freezing. Localized early-morning freezing temperatures can extend from the Dakotas, Minnesota and Wisconsin to West Virginia, northern New Jersey, central Massachusetts and coastal Maine.
As the core of the cold air settles in, daytime temperatures in parts of the Great Lakes region to the higher ground in the central and northern Appalachians will be no higher than the 40s.
Even though the sun may be out to start the day in coastal areas, temperatures will drop 10-20 degrees during the daytime as dark clouds move in and showers move through.
High temperatures over the Ohio Valley and along much of the Interstate 95 corridor of the mid-Atlantic will be in the 50s even with partial sunshine. RealFeel Temperatures in shaded areas and during cloudy intervals can be 10-15 degrees lower, factoring in wind and other conditions.
Snow showers are most likely from the Minnesota Arrowhead to northern Michigan, parts of Ontario, western Pennsylvania, western and northern New York state and the mountains of northern New England.
The snow could cover non-paved surfaces in a few spots.
According to AccuWeather Winter Weather Expert Brian Wimer, "Snow showers during the event will tend to occur away from the immediate lake shore areas and over higher elevations."
Motorists traveling along portions of I-75, I-86, I-89, I-90 and I-196 should be prepared for sudden low visibility as snow showers could move in.
It is possible for thunder and lightning to accompany some of the rain and snow showers.
Waterspouts may form around the Great Lakes, especially over lakes Michigan, Erie and Ontario.
Small craft operators should expect waters to become very choppy with the roughest conditions during Friday and Saturday.
"The October cold spell will not be long-lived and will generally be limited to a couple of days," Dombek said.
Following the building chill into this weekend, another warmup is in store during the first part of next week.
According to AccuWeather Chief Meteorologist Elliot Abrams, "The first stage of the anticipated El Niño winter weather pattern will follow later next week in the Central and Eastern states."
The El Niño pattern is already setting up in the Southwest United States this week.
AccuWeather.com will have more information on the El Niño winter pattern for the U.S. later this week.