The northern Rocky Mountain region will be subjected to an attack of severethunderstorms Saturday afternoon and evening. The storms will be caused by arapid destabilization of the atmosphere as cool air aloft runs across heatedsurface air.The storms will bring large hail and surface wind gusts over 60 miles per hour.

A few tornadoes may touch down, but any that do will be the smaller variety.

Getting an EF4 or EF5 tornado in this part of the country is almost unheardof.

Story by AccuWeather.com Senior Meteorologist John Kocet.