Quick surges of frigid and mild air will produce dramatic temperature swings from one day to the next in the East.
The temperature swings of 25 to 50 degrees in a matter of hours will make it very hard for some people adjust and can lead to melting and freezing cycles that cannot only rupture water mains but also cause ice to form following bouts of melting snow.
During the cold days, when the wind is blowing, combined with other atmosphere conditions, RealFeel® temperatures will can be 10 to 30 degrees lower than the actual temperature.
Air blasting southward from eastern Canada on Friday will send temperatures down to their lowest levels since January 2009 in many locations from New England to part of the mid-Atlantic.
This includes temperatures dipping well below zero from northern Pennsylvania to the Hudson Valley of New York to southern New England, on northward into neighboring Canada. Cities that will plunge below zero Friday night include Boston, Hartford, Conn., and Scranton, Pa.
Lows in the single digits are forecast Saturday morning from Pittsburgh to Baltimore, Philadelphia and New York City.
However, after a cold day on Saturday, temperatures will rebound to above-average levels from the Appalachians to the coastal mid-Atlantic and southern New England.
According to Long Range Weather Expert Paul Pastelok, "Temperatures will reach the 40s in Washington, D.C., Baltimore, Philadelphia and New York City on Sunday."
The warmup will not set a new trend.
Already Sunday, another blast of frigid air will be charging in. This one will arrive from the west and will sweep across the Ohio and Tennessee valleys and into the Appalachians Sunday night in the wake of snow, a quick freeze and even a blizzard in some areas.
The new blast of frigid air will push over the Appalachians and to the Atlantic Seaboard during Monday.
"Temperatures Monday that start near mild levels in the 40s and even near 50 degrees in some locations will crash below freezing as the day wears on," Pastelok said.
Temperatures are forecast to plunge toward zero Monday night in the Appalachians and into the teens along the I-95 corridor. Temperatures may rise very little Tuesday, from the 8:00 a.m. lows.
Temperatures will start the day Monday and Tuesday below zero over much of the Ohio Valley and may rise to only the single digits.
"Around the western Great Lakes, such as Chicago, temperatures are likely to remain below zero around the clock on Monday," Pastelok added.
The last time temperatures were this low was during early February of 1996 in Chicago and vicinity.