The National Weather Service is warning Maine residents to prepare for severe thunderstorms this afternoon and evening, with golf ball-sized hail, winds over 70 mph and a tornado risk that is 50 times higher than on a normal summer day.

“We forecast severe thunderstorms fairly often in the summer, but this is a level above what we normally see,” said Chris Legro, a meteorologist in the National Weather Service’s Gray station. “People need to stay alert, have a way to receive our warnings and have a plan to take shelter.”

A typical Maine summer thunderstorm can produce 1-inch hail, winds of up to 60 mph and a slim chance of a brief tornado, he said. The storms likely to hit Maine late afternoon Tuesday through early Wednesday will probably be much worse, he said.

These storms could yield hail that is two inches in diameter, which is slightly larger than a golf ball. One-inch hail stones can damage or destroy crops, Legro said, but two-inch ones can dent cars and crack windows.

Storm winds could top 70 miles per hour, he said. The likelihood of a tornado is between 2%-5% — 25 to 50 times higher than a typical summer day, Legro said. If a tornado does form, it could be a strong one, capable of ripping off roofs, demolishing mobile homes and snapping large trees.

The National Weather Service is still forecasting high heat and humidity into early Wednesday, but not quite as high as originally forecast due to a slow-to-fade cloud cover. Still, the Fryeburg-Sanford region is likely to see highs in the upper 90s, Legro said.