Barnum began his coaching career as a high school assistant coach in Washington state, first at
Central Valley High School in
Spokane Valley in 1986 then with his alma mater Columbia River High School from 1987 to 1988. Barnum led the Vikings to a 24–17 upset over the
Washington State Cougars at
Martin Stadium in
Pullman, WA on September 5, 2015 for his first career victory as head coach. On October 10 Portland State defeated
North Texas 66–7, giving Barnum and the Vikings their second victory over an FBS school in 2015. The 59-point win set a new NCAA record for the largest margin of victory by an
FCS school over an
FBS opponent. Barnum became the inaugural
STATS FCS Coach of the Year for leading Portland State to a 9–3 season and first
FCS Playoff appearance in 15 years. Barnum has occasionally been criticized for deriding opposing teams. For example, in the week leading up to Portland State's 2016 road matchup with Southern Utah, he caused ripples of outrage in the Utah media when he stated, referring to Cedar City, UT (home of SUU), "I didn't want to stay in Whoville. We are going to stay up in the Grinch's Castle [referring to nearby Brian Head, UT]. We are going to go down, play them Saturday, whoop up on them." In response to the comments, SUU fans showed up to the game en masse, setting a single-game school attendance record. Many carried signs and banners mocking Barnum's statements, while others dressed up as characters from "How the Grinch Stole Christmas". SUU won the game, 45–31. ==Personal life==