Severe thunderstorms and potential tornado activity threatened Colorado's Front Range and eastern plains Monday.

Afternoon thunderstorms brought hail on Monday afternoon, larger than a quarter in some areas. Thornton, Wheat Ridge and Arvada were among the communities hit with hail. A line of storms moved from the foothills through the Denver metro area and out to the Eastern Plains.

Denver International Airport faced flight delays and cancellations as a tornado watch was issued across Colorado, with severe weather warnings for hail and strong winds.

Workers at Armstrong Contracting are busy checking roofs in the Whittier neighborhood of Denver. Many suffered hail damage in the June 1 storms.

A line of Monday storms with hail moved down from the Colorado foothills in the afternoon, then across the Front Range and out to the Eastern Plains.