Gusting winds, blowing snow and plummeting temperature chased commuters home on Thursday evening over slick roads snarled with dozens of traffic accidents that began piling up soon after the snow did.
The National Weather Service forecast snow accumulation of 2 to 4 inches for most of southwest Pennsylvania, but warned that the bigger worry would be dangerously low temperatures, with a low around 5 degrees and wind chill values as low as minus 11 expected Thursday night.
Scattered snow showers are expected again today before 9 a.m., with little or no accumulation expected, and continued cold temperatures of 15 for a high with wind chill values as low as minus 14, according to the weather service.
Extreme cold temperatures can keep roads slick because they hinder the effectiveness of road salt, which cannot melt snow and ice as well at very low temperatures.
Normal temperatures for this time of year are between the mid-30s and the low 20s. In addition, morning commuters should watch out for gusty winds playing havoc with snow accumulations, which had already reached 3 inches last night in many areas, said weather service meteorologist Brad Rehak.
"It's going to be blowing around because it's all light and fluffy," Mr. Rehak said of the snow. "There will blowing and drifting across roads."
Friday's winter storm was part of a massive system that created blizzard-like conditions throughout much of the East Coast, with 18 inches of snow predicted for Boston, and high winds and subzero temperatures expected to affect millions of people across the Northeast.
In Allegheny County, icy conditions and accidents called emergency crews to more than a dozen crashes on Route 28 and I-279, and in Mt. Lebanon, Franklin Park, Pleasant Hills, South Fayette, Ross, Glen Osborne, Penn Hills, Richland, Windgap, Ohio Township, Avalon, Pine, Indiana Township, Leetsdale, Springdale and in Pittsburgh, to the North Side, Uptown, Morningside and Lawrenceville, according to county officials.
In addition, icy road conditions prompted county officials to caution travelers in Pine on West Wild Cherry Drive at Franklin Road, and to close South Negley Avenue from Fifth Avenue in Shadyside to Dunmoyle Street in Squirrel Hill, and Stanton Avenue from Morningside Drive to Chislett Street.
At Pittsburgh International Airport, more than 30 flights -- mostly to Chicago, Cleveland, New York, Newark, Boston and Hartford, Conn. -- were canceled or delayed beginning Thursday at about 3 p.m., according to airport officials.
The airport, however, had three of its four runways operating, "which is plenty of landing areas," said airport director of communications JoAnn Jenny. The runways were being plowed and salted continually, and planes were being deiced before takeoff, she said.
"Right now we're really running rather well," she said.
PennDOT said it will do what it can to keep the roads clear as holiday travelers traverse the state.
Its crews will work around the clock, but drivers shouldn't expect roads to be free of ice or snow while it's still snowing. Those who don't need to travel shouldn't, PennDOT said.
More than 50 school districts, churches and community groups -- including Pittsburgh Public Schools, Mt. Lebanon School District, Apollo-Ridge School District, Avonworth School District, Upper St. Clair School District and all campuses of the Community College of Allegheny County -- cancelled Thursday's evening activities and dozens of schools and groups announced a two-hour delay this morning. For a complete list of delays and closings, go to http://pittsburgh.cbslocal.com/school-closings.
Weekend temperatures are expected to hit a balmy 37 degrees on Sunday before plunging again to 17 degrees amid near-certain snowfall on Sunday night. Highs in the early part of the week are forecast to reach 17 degrees, with a breathtaking high near zero on Tuesday.
If the high stays below zero, it would be only the eighth such subzero high since recordkeeping of temperatures began in 1871, Mr. Rehak said. Other such highs were recorded at minus 3 on Jan. 17, 1982, Jan. 19, 1994, and Feb. 9, 1899; and at minus 2 on Jan. 23, 1936, Feb. 10, 1899, Jan. 24, 1963, and Jan. 17, 1977.
Emergency officials also advised residents to stay indoors as much as possible, and to wear several loose-fitting warm layers of clothing and to cover exposed skin if they must go outdoors.
Frostbite -- loss of feeling and a white or pale appearance in extremities such as fingers, toes, ear lobes and the tip of the nose -- can occur within 30 minutes at a wind chill temperature of minus 19 and within 10 minutes at a wind chill of minus 33, county health officials said.
Amy McConnell Schaarsmith: firstname.lastname@example.org.
Amy McConnell Schaarsmith: email@example.com. Jacob Sanders and Torsten Ove contributed. First Published January 2, 2014 10:38 AM