The National Weather Service office in Gray is warning of a growing risk for flash flooding in Maine that could occur late Monday night into Tuesday.

Forecasters are predicting that a “dynamic weather system,” capable of producing multiple rounds of rain and thunderstorms, will generate moderate to heavy rainfall throughout most of western, central and southern Maine, especially on Tuesday.

Meteorologist Jon Palmer described the incoming weather pattern as “training,” where storms line up on top of each other often moving over the same area and dumping heavy rain on that area in a short period of time. Palmer said there will be thunderstorms embedded within the storm train.

The storms will arrive in Maine late Monday and continue throughout most of the day Tuesday.

Because the storms will be slow moving and dropping heavy rain, the National Weather Service is warning of flash flooding in certain, localized areas. Streams and river levels could rise dramatically in low-lying areas.

“Flash flooding is possible across the region. At least an inch of rainfall is expected over all of New Hampshire and Maine,” the National Weather Service wrote in a Facebook post Sunday night. “Localized (rainfall) amounts of three or more inches are possible with repeating and slow moving storms.”

Palmer said it looks like the heavy rain will be widespread Tuesday, with the threat of thunderstorms starting as early as Tuesday morning throughout much of Maine.

Almost exactly one year ago, the U.S. Drought Monitor reported that all Maine counties, except for Aroostook, were experiencing severe or moderate drought or abnormally dry conditions. In addition, the Maine Department of Environmental Protection said then that water levels in many streams, rivers, lakes and ponds were at levels below the median level for August.

Last year represented the third consecutive year that parts of Maine have experienced drought conditions, but that has not been the case in 2023.

According to Palmer, 33.84 inches of rain has fallen at the Portland International Jetport as of Aug. 6, closing in on the total rainfall amount at the jetport for all of 2022, which was 46.66 inches. The Portland Jetport had reported 19.78 inches of total rainfall as of Aug. 6, 2022.

Palmer noted that there was a soaking rainstorm that swept through the state in late December 2022. That storm, which struck Dec. 23, brought torrential rain and hurricane force winds to much of Maine, causing flooding and damage in coastal communities, leaving roughly 255,000 customers without power, and disrupting travel plans for many two days before Christmas. Even one of the state’s most well-known landmarks, the Portland Head Light, sustained significant damage.

“It has been raining since the start of 2023,” Palmer said.

The weather service is urging people not to attempt to cross a flooded road on foot or in a vehicle. It is also warning people who have set up camp near a river or stream to pay attention to a sudden rise in water levels near their campground.