(Adds six missing in Nevada and Bears' game weather)
By Carey Gillam
Dec 9 (Reuters) - A deadly winter storm kept a tight grip on much of the United States on Monday as cold, snow and ice spread across the East Coast, snarling traffic and knocking out power to thousands.
As much as 5 inches (12.7 cm) of snow were forecast for Monday night into Tuesday and much of the area from Virginia to coastal New England were under winter weather advisories, the National Weather Service (NWS) said in a forecast.
Bitter Arctic air in the upper Great Plains and Rocky Mountains is expected to persist through Wednesday, with the coldest weather extending from the Nevada-Utah region into Minnesota, the NWS said.
"I don't think things are going to warm up any time soon," said Bruce Sullivan, an NWS meteorologist.
The cold snap will drive temperatures well below average across the United States through midweek, including Texas and the South, the NWS said.
Thousands of homes and businesses were without power on Monday morning. Thousands of flights were delayed as snow and ice covered roads, highways and airport runways from Texas and Oklahoma east to Virginia and north through Pennsylvania.
Northern Maryland, central and eastern Pennsylvania and parts of New York state received up to 10 inches (25 cm) of snow through Monday morning. Sleet and freezing rain also pummeled the area, according to the NWS.
29 BELOW ZERO FAHRENHEIT
The mercury in Daniel, Wyoming, fell to 29 below zero Fahrenheit (minus 34 Celsius) on Monday, marking the coldest temperature in the contiguous United States.
In remote northwestern Nevada, rescuers were searching for two adults and four young children a day after they were last seen near an abandoned mining camp where they had gone to play in the snow, local authorities said.
The couple had taken their two children and niece and nephew, who range in age from 3 to 10, on an outing to an old mining camp in the Seven Troughs mountain range, the authorities said.
A spokeswoman for the Oklahoma State Department of Health said it had tallied 247 storm-related injuries. The Oklahoma Highway Patrol has reported 201 collisions that did not cause injuries and 65 collisions that resulted in injuries.
On one stretch of highway near Philadelphia, more than 50 cars and trucks were caught in chain-reaction crashes on the Pennsylvania Turnpike on Sunday afternoon. One man was killed when he left his vehicle after the crashes, a turnpike spokesman said.
AAA Mid-Atlantic, the auto group, said it pulled 109 vehicles out of snow and ice in Pennsylvania on Sunday, compared with three the week before.
At least three people were killed in weather-related car accidents in Arkansas and Tennessee, emergency officials said. Virginia officials warned drivers of hazardous travel conditions.
Oklahoma Governor Mary Fallin declared a state of emergency in the state, where the winter weather contributed to at least three deaths, including two young boys in weather-related accidents and a homeless man from the cold.
NFL FREEZE, WHITEOUT
City of Chicago officials warned football fans to take extra precautions against the weather for the Bears' Monday night match against the Dallas Cowboys, since the wind chill at Soldier Field is expected to be below zero.
The game is expected to be well-attended despite what is locally known as "Bear weather," since "89," the jersey number of former player and coach Mike Ditka, is being retired.
About 1,700 flights were canceled nationwide on Monday, according to tracking website Flightaware.com.
About 650 travelers were stranded overnight in the Dallas/Fort Worth International Airport overnight on Sunday, officials said. About 350 flights at the airport were still canceled in Monday, airport officials said.
Some 267,000 customers in Texas lost power at the height of the storm and about 21,000 homes and businesses remained without power on Monday, said utility Oncor.
Freezing weather across Texas set successive December power use records on Friday and Saturday, according to preliminary data from ERCOT, the state's power grid operator.
(Reporting by Carey Gillam in Kansas City; Additional reporting by Heide Brandes in Oklahoma City, Jana Pruet in Dallas, Dave Warner in Philadelphia, Ian Simpson in Washington, D.C., Jonathan Kaminsky in Olympia, Washington, and Mary Wisniewski in Chicago; editing by Jeffrey Benkoe, Matthew Lewis and Cynthia Osterman)