A combination of astronomically high tides and storm surge from Thursday’s expected blizzard could cause midday coastal flooding in southern Maine and New Hampshire, according to weather forecasts.

On Wednesday afternoon the National Weather Service in Gray issued a coastal flood warning for Portland and for points south into New Hampshire. Water pushed toward shore by strong winds is expected to produce tides up to 13 feet high around 12:30 p.m. Thursday.

“This will allow for a foot of water to inundate side streets along the wharfs in Portland,” NWS forecasters said. “In some areas, water will reach the tailpipes of parked cars. Expect about a foot of water to inundate Granite Point Road in Biddeford and localized flooding of other shoreline communities.”

In New Hampshire, flood waters could reach a depth of up to two feet in Hampton, including flooding on Ashworth Avenue, they added.

“Beach erosion, splash-over and coastal flooding may continue for a couple hours after high tide as the brunt of the storm passes by, especially in the estuaries which are normally slow to recede,” NWS forecasters said in the warning.

A coastal flood advisory, which carries less urgency than a warning, also was issued for coastal Hancock and Washington counties. Due to the timing of the storm’s progress up the coast, the advisory for eastern coastal Maine will be in effect late Thursday night and early Friday morning, roughly 12 hours after coastal flooding is expected in southern Maine and New Hampshire.

“Some low-lying causeways will have water beginning to approach the road with up to 1 foot of inundation,” NWS forecasters wrote in the advisory. “A majority of roads will remain passable with only isolated closures.”

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Bill Trotter

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....