Portland, OR -

Stormy conditions Thursday morning caused several crashes on Interstate 5 in the central Willamette Valley, including one estimated to have involved as many as 20 vehicles.

Lt. Steve Mitchell called the stretch of Interstate 5 between Salem and Albany "pure chaos" and advised drivers to avoid the area except in emergencies. There were no immediate reports of injuries.

State transportation officials said southbound lanes of I-5 were closed three miles north of Albany as a result of a pileup of up to 20 vehicles. The northbound lanes were closed south of Albany by another crash.

Forecasters say a storm Thursday could leave the most widespread snowfall since 2009 in the northern and central valley.

Snow is in the forecast for most of Oregon.