By Chris Spears

DENVER (CBS4) – A surge of smoke filled the sky in Denver late Saturday afternoon. Numerous people posted on Twitter that they were smelling wildfire smoke along the Interstate 25 urban corridor.

The smoke near the surface was from a grass fire sparked by lightning Friday night in Morgan County, near the town of Wiggins. Gusty northeast winds behind a cold front caused the fire to reignite Saturday afternoon. Those same winds were transporting the smoke down the South Platte River Valley and into the Denver metro area. The plume of smoke is circled in red on the map below.

A visible satellite image snapped from the Meteorology Department at the College of Du Page. (credit: College of Du Page)

In the mid and upper levels of the atmosphere wildfire smoke from California was flowing into the state as well. It was thick enough to prompt an Air Quality Alert on Saturday in parts of northwest Colorado.

Chris Spears