I live in Illinois, which is flat prairies. Traveled through western NV about 10 yrs ago in April thinking it was spring so no worries. Checked the weather & nothing was mentioned. However, it started dumping snow & everything else. Driving in to clouds or what ever made me realize that mountains only look good in photos & possibly July in person.
As far as your Grand Junction idea. 70 across CO is not exactly a cake walk & you would still have to cross Vail Pass.