DENVER Winter returned to Colorado overnight Saturday, leaving slick roads across the Denver area that are causing multiple crashes Sunday morning.At least four separate vehicle crashes on Interstate 225 in Aurora are being bla med on the conditions, according to police.No immediate information was available regarding injuries in these incidents.Police said Colorado Department of Transportation plows were en route to clear roads and apply more salt. MORE | Latest Colorado road conditions and travel informationFurther south, where conditions are worse, multiple crashes and spinouts were reported on Interstate 25 near Monument, leading to periodic closures.Meanwhile, a crash west of Limon briefly closed westbound Interstate 70 Sunday morning.In the mountains, crashes and spinouts are causing periodic closures on I-70.A winter weather advisory is now in effect for the Palmer Divide, and the I-70 mountain advisory has been extended to noon due to ongoing snow and difficult travel.Very strong winds will continue on the plains through midday, gusting 5055 mph, possibly higher near the I-70 corridor, before easing this afternoon. ...read more read less