This was supposed to be the first day back at school following winter break for most Iowa students, but classes were cancelled in many districts by foul weather. Frank Boksa, a meteorologist at the National Weather Service office in metro Des Moines, says the ice and freezing rain has made driving hazardous. Much of southern Iowa is under an ice storm warning, while a freezing rain advisory stretches across central Iowa up to Waterloo — both through noon. A winter weather watch is also in effect for Tuesday night and into Wednesday morning. Boksa says there’s the potential for heavy snow in that storm system.The storm could drop over a full inch of liquid precipitation which could equate to anywhere between six and ten inches of snow, depending on the temperature. The system is still developing and Boksa says it’s uncertain just how much snow will fall where on Iowans. Most of the state will get at least some light snow Tuesday night and into Wednesday but the heavy band of snowfall is still hard to pinpoint. Officials in Ottumwa say ice-covered branches began falling on power lines late this morning. Also this morning on Interstate-80 near Newton a semi jack-knifed and other vehicles slid into ditches, prompting the temporary closure of the roadway.