Des Moines, IA (AP) — The National Weather Service says a tornado touched down in northwest Iowa Sunday evening, but no substantial damage or injuries were immediately reported. The weather service's Des Moines office reports the tornado was documented by a storm chaser at 11:23 p.m. north of Otho, Emergency managers reported some tree damage, including downed limbs in Dayton. Funnel clouds were reported further to the northwest between 8:40 and 9 p.m., and tornado warnings were issued for six Iowa counties at various times Sunday night.