A Saturday night storm that dumped more than 4" of snow on parts of the Omaha metro promised to keep roads treacherous well into Sunday.The National Weather Service upgraded several western Iowa counties to a Winter Storm Warning as snow amounts started piling up. Travel in eastern Pottawattamie County was not recommended.Omaha and Council Bluffs police went on accident alerts Saturday evening, limiting police responses only to crashes where people were injured, or where vehicles could not be moved.By 10:00 p.m., 4" snowfall reports were becoming common in Douglas and eastern Sarpy counties. The Nebraska State Patrol urged drivers to exercise caution, but in a tweet, said that most drivers were handling the conditions. Still, numerous accidents were scattered across the metro, but as of late Saturday, no serious injuries had been reported.Omaha and other communities were planning to plow throughout the night to clear major streets as the snow was expected to taper-off after midnight.