Snow overnight tonight will accumulate mainly in north central Iowa where 1 to 3" of snow is expected. Des Moines will likely see 0.5" to 1".
A better chance for snow will arrive on Saturday for all of Central Iowa. On Saturday the snow will start in NW Iowa and intensify toward midday. Snow should arrive in Des Moines around 4pm, with most accumulations occurring in the metro from late afternoon through the evening.
Additional snow is possible Sunday south of I-80, particularly along the Iowa-Missouri border.