Pittsburgh's homeless population filled local shelters by the dozens Monday night to escape temperatures that were forecast to plunge to 5 degrees and piercing wind gusts that were expected to create a wind chill as low as 20 degrees below zero.
More than 50 people, many wearing clothes insufficient for a typical winter's night, lined up outside the Severe Weather Emergency Center, Downtown, waiting for a hot meal, a warm shower and a mattress to sleep on.
"I've been sleeping in cardboard boxes," said Donnie, a 58-year-old man who declined to give his last name.
When the doors of the Smithfield United Church of Christ, where the shelter is housed, opened at 7 p.m., many of the men quickly grabbed a mattress and claimed coveted spots against a wall in the church on Smithfield Street.
The women, who were later taken by bus to Shepherd's Heart Veteran's Home in the Hill District to sleep, swarmed the food line.
The basic purpose of the Severe Weather Emergency Center, run by Pittsburgh Mercy Health System's Operation Safety Net and the Allegheny County Department of Human Services Office of Community Service, is to prevent the city's homeless from freezing.
"When we first started, there were numerous cases of frostbite," said shelter manager Mark Daly.
"We're not aware of any cases for the last eight years," said Jim Withers, Operation Safety Net's medical director. Dr. Withers founded Operation Safety Net in 1992 by providing health care to individuals without shelter.
The National Weather Service in Moon expected temperatures between zero and 5 degrees Monday night to combine with west winds of about 15 mph to produce a wind chill between 10 and 20 degrees below zero.
Forecasters predict the wind chill today will rise to between 10 below and zero and fall back to 10 to 20 below zero tonight and Wednesday morning.
Anyone who spends as much as a half-hour outside in the frosty weather the region is experiencing without proper shoes or gloves can expose themselves to frost nip, said Clifton Callaway, a professor of emergency medicine at the University of Pittsburgh and a doctor in UPMC Presbyterian's emergency department.
Frost nip results from the skin's exposure to cold temperatures and differs from frost bite in that it causes a burn and does not freeze an extremity.
He advised people to protect their ears and face, stay out of the wind and keep their extremities dry.
"Your body makes the cold unpleasant for a reason," he said.
He reminded people to allow their bodies to warm up naturally indoors and avoid sticking their hands in hot water or on a radiator, because the numbness from the cold can block a person's ability to realize their skin may be burning.
While the wind and low temperatures will persist through Wednesday -- temperatures are expected to drop as low as 3 below zero tonight, with winds as high as 30 mph through Wednesday -- the worst precipitation is over.
The National Weather Service reported 2 inches of snow Monday at its facility in Moon. Less than an inch was predicted to fall overnight, and today is forecast to be mostly dry with a few scattered flurries.
Taryn Luna: firstname.lastname@example.org or 412-263-1985. First Published January 22, 2013 5:00 AM