CNN

(CNN) – A major ice storm is forecast for the northern half of Ohio as voters go to the polls to vote in a primary there that may determine Sen. Hillary Clinton’s fate and seal the GOP nomination for Sen. John McCain.

Dayton and Columbus will likely see some wintry weather but be spared the worst of the ice and sleet forecast for Toledo, Mansfield, Cleveland, Akron, and Canton.

The storm is projected to begin before polls open at 6:30 a.m. ET Tuesday morning and last much of the day, and there is a potential for widespread power outages in the region.

Heavy rain and thunderstorms are also possible in the southern part of the state, where flood watches are in effect.

Another state is expected to experience a primary day storm Tuesday: much of Vermont is likely to see winter weather Tuesday, with the heaviest snow, sleet, or ice expected in the afternoon.

After a stormy Monday in Texas, the Tuesday forecast calls for calm skies.

–CNN’s Dave Hennen and Martina Stewart