The “supermoon” combined with astronomical high tides will likely cause minor flooding in parts of Portland and other coastal communities Tuesday morning, although meteorologists say a rainstorm should arrive late enough to avoid serious problems.

Tuesday’s “king tide” – the name given to the highest anticipated tides of the year – will bring water levels topping off at 12 feet above mean low water, more than 2 feet higher than the average high tide in Portland. That is high enough to cause “nuisance flooding” in areas such as Portland’s Bayside neighborhood and along Commercial Street.

The National Weather Service issued a coastal flood warning from the Maine-New Hampshire border to Portland from 10 a.m. to 2 p.m. on Tuesday. The weather service said “minor coastal flooding is likely” from Portland south during that time.

Bill Needelman, the city’s waterfront coordinator, was optimistic Portland wouldn’t see a repeat of September 2015’s severe flooding, when astronomical high tides left the stormwater management system unable to cope with a massive rainstorm.

“It’s not an unusual circumstance,” Needelman said. “It just so happens to be around a 12-foot tide, which we have experienced many times in the past. As long as we don’t experience significant rain along with it, we should only experience ponding” in flood-prone areas.

“It could have been a lot worse,” noted John Cannon, a meteorologist with the weather service in Gray.


Tides are, of course, caused by the gravitational pull of the moon. And this week’s so-called “supermoon” is closer to Earth than it has been in 68 years, hence the extra-large appearance of the moon this past weekend and Monday night.

But “king tides” typically cause problems in Maine only when they are accompanied by a major storm bringing rain and winds that push water ashore.

Cannon said Tuesday will likely be rainy and windy but the storm isn’t expected to arrive until after the late-morning king tide has begun to recede. Yet Cannon added that “we’re only talking about a difference of an hour or so,” meaning an earlier-than-anticipated arrival of the rain and wind could still cause more severe flooding along the coast. And then there is the question of whether the storm will cause headaches during the high tides Tuesday night or Wednesday morning.

“We’re not out of the woods yet,” Cannon said. “Even though Wednesday morning’s tide is not the highest tide of the year, it is still 11.9 feet.”

On Monday, Portland officials urged residents and city visitors to use caution when parking in or driving through the following flood-prone areas: Somerset Street in Bayside, Marginal Way east of Boyd Street in East Bayside, Park Avenue near Interstate 295, and near the Portland waterfront on Portland Pier and parts of Commercial Street.

The city advised residents to avoid leaving vehicles for prolonged periods in flood-prone areas and not to drive or walk through water-covered roads because of the risk that manhole covers were displaced by the water.


After the September 2015 flooding, which left numerous cars stranded, the city took steps to improve communication between departments and with the public, Needelman said. The city will have barricades in place to close flooded streets or intersections, if needed. City officials, local business owners and neighborhood representatives will also meet at high tide Tuesday to walk through the Bayside neighborhood.

Other coastal towns were also taking steps to remind residents about the flooding potential.

In a posting on the department’s Facebook page, Kennebunkport police warned residents of flood-prone areas “to take added precautions in ensuring property is protected or moved to higher ground.”

“Emergency crews will be monitoring roads and may need to close them because of water levels,” the post says. “Caution should be used when traveling in coastal areas for the next two days. It is never advisable to drive through areas of standing water, especially salt water.”

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