An early morning snow squall led to icy roads and crashes in Philadelphia on New Year’s Day, including one accident that left two people in critical condition. According to the National Weather Service, snow squalls are intense but quick periods of moderate to heavy snowfall accompanied by gusty winds that reduce visibilities and lead to whiteout conditions on roads. A fast-moving cold front brought a snow squall to the Philadelphia area around 5 a.m. on Thursday. While the system quickly moved