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 be 10 to 30 degrees lower than the actual temperature.
Air blasted southward from eastern Canada on Friday night, sending temperatures down to some of their lowest levels since January 2009 in many locations from New England to part of the mid-Atlantic including, Boston, Hartford, Conn., and Scranton, Pa.
Lows bottomed out in the single digits Saturday morning from Pittsburgh to Baltimore and even dropped below zero farther north in places such as Scranton, Pa. and Albany, N.Y.
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 across the Central states. 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.
Rounds of rain will bring good news for unusually dry portions of the northeastern United States to start May.
Residents of the southeastern United States may feel like the calendar has flipped ahead to Memorial Day weekend with warm and muggy weather in place for the start of May.
A stormy pattern will persist across the western Gulf Coast into early May, threatening to trigger more flooding from Texas to Mississippi through at least Monday.
May is picking up where April left off with record-challenging warmth surging back into the northwestern United States.
Those looking to traveling or spending the bank holiday outdoors across the United Kingdom will face bouts of rain and wind, but dry conditions will follow by midweek.
A late-April snowstorm dumped over a foot of heavy, wet snow across parts of Colorado on Thursday into Friday, boosting snowpack for an extended ski season at local resorts.
Unusually late coating of snow in Washington, D.C., Baltimore and Philadelphia.
United States (1982)
May produced 365 tornadoes in the U.S., the highest number for any month since reliable records have been available, according to NOAA. The May figure topped by 90 the May 1965 high of 275.
Guangxi, China (1986)
Hailstones weighing up to 11 pounds killed 16 people and injured 125.