Strong winds and severe thunderstorms blowing through Maine Monday afternoon and evening are part of a large system that is already disrupting air travel along much of the East Coast.

The Portland International Jetport posted a notice on Twitter that airports in New York City, Philadelphia, Baltimore and Washington, D.C., are all showing flight delays and cancellations for Monday afternoon because of thunderstorms moving east.

“A rough afternoon is expected for our New York City flights. Check with your airline for current flight info,” the Jetport said in a post.

The National Weather Service in Gray has issued a severe thunderstorm watch until 8 p.m. for much of Maine, New Hampshire and Vermont. The midcoast and Downeast regions are the only parts of Maine not included in the watch area.

Smaller scale sever thunderstorm warnings were posted later Monday afternoon for the Lewiston area and the Sebago Lake region.

The thunderstorms are expected to hit hardest in western Maine communities such as Sanford, where there is a 70 percent chance of severe thunderstorms Monday afternoon, with possible large hail and damaging winds, according to the weather service.

In Portland, there is a 30 percent chance of showers and thunderstorms late Monday afternoon and an 80 percent chance of thunderstorms later Monday night, according to the weather service.

This story will be updated.