Look for a low pressure system to move through, which also signifies a storm front, as storms come with low pressure. I wouldnt really rely on barometer though, just because I dont know what a normal reading is LOL. Just listen to the weather man, and watch for that triangle crescent to move across your state. (I think triangle is low, it may be a half circle to signify low pressure)
http://upload.wikimedia.org/wikipedi...e_analysis.gif