Thunderstorms, heavy wind, and rain threaten to deter voters from going to the polls on Election Day

• The midterm elections are taking place across the US on Tuesday, but bad weather threatens to keep less committed-voters from the polls.
• Every state east of the Mississippi River is expected to see rain at some point today while polls are open.
• More severe weather is forecast in several states with contentious races, including Georgia, New Jersey, and Florida.

Polls opened across the country Tuesday morning as the nation votes in the midterm elections, but bad weather is threatening to impact several key races in the eastern United States.

Every state east of the Mississippi River is likely to see rain at some point while polls are open today, CNN reported, and there are several areas where more severe weather - including thunderstorms and gusting winds - could keep less-committed voters from the polls.

Democrats are hoping Tuesday's elections win them back control of Congress, but at least one study has shown that Republicans have an advantage on rainy election days.

Read more: See what time the polls open and close in every state

Thunderstorms up and down the East Coast, snow in the Rockies, and rain in the Midwest

Weather.com predicts rain and thunderstorms to drench areas of New England down to the northern Gulf Coast.

"A windy, raw day is in store in the Great Lakes, which may keep some from venturing out to the polls," Weather.com meteorologist Jon Erdman said. "Some light snow in parts of the northern Rockies shouldn't be too much of an impediment for voters in those areas."

In Georgia and Florida, where two of the most contested governors' races are taking place today, scattered showers and storms are expected.

A storm system that killed one in Tennessee last night is moving east and will bring severe thunderstorms and heavy winds from Charlotte, North Carolina to Philadelphia.

Accuweather suggests that voters in the Greensboro, North Carolina; Roanoke, Virginia; and Harrisburg, Pennsylvania areas vote in the afternoon, since the morning is expected to be wet.

Washington, DC and Philadelphia are likely to be stormy in the morning and the middle of the day, so voters there should aim to go to the polls in the afternoon and evening if they want to stay dry.

Meanwhile, Norfolk, Virginia; Raleigh, North Carolina; Dover, Delaware; Atlantic City, New Jersey and New York City are expected to have the best voting conditions in the morning, before rain hits in the evening.

Jim Geraghty, senior political correspondent for the conservative National Review, tweeted Tuesday morning that the rain was "coming down in buckets" in northern Virginia, where close House elections are taking place in the state's 7th and 10th districts.

"Get ready for weather-scapegoating," he said.

Could rain be good for Republicans?

Rain certainly will have an impact on the election, but to what extent is unknown.

"Drizzle drives a few people away from the polls; a heavy downpour keeps a whole bunch of them away," Larry Powell, pollster and professor of political communications at the University of Alabama Birmingham, told Weather.com.

Powell says campaign organizers pay close attention to weather in races, and will often organize transportation to take voters to the polls if they're hesitant to drive themselves.

He went on to say that inclement weather tends to favor the incumbent.

"Sunny days benefit the challengers more than the incumbents," he said. "The incumbent voters are going to get to the polls regardless."

Some scientific research also suggests that Republicans have an edge in bad weather.

A study first conducted in 2015 and revised last month from researchers at Dartmouth College and the Australian National University showed that at least 1% of voting-age adults who would have voted blue if the weather had been good, voted Republican instead on rainy election days.

"Our study suggests that weather conditions may affect people's decisions on not only whether to vote but also who they vote for," Dartmouth government Professor Yusaku Horiuchi, a co-author of the study, said in a news release.

A separate study from 2007, conducted by Florida State University, also found a Republican advantage on rainy election days.

But the lead author of the study, political scientist Greg Gomez, said that the correlation is more pronounced in presidential elections.

Gomez told Weather.com that the midterms are different since they are disproportionately composed of "core voters" who are usually more partisan and less susceptible to changing their mind.

"We would expect that bad weather is a bigger deterrent to voting in presidential elections than in midterm elections; midterm electorates simply are composed of a larger percentage of core voters who are determined to vote rain or shine," Gomez said.

He also says that more states now hold early voting, which wasn't the case when his study was conducted.

But this year's elections are looking more like a presidential election with possible record turnout for a midterm year, so it remains to be seen how the weather will affect the results.