Coastal flooding expected with storm on Friday

An impending storm threatens to destroy homes up and down the coast and flood parts of downtown Boston, according to Gov. Charlie Baker, who activated National Guard troops on Thursday and warned people to be ready to evacuate if ordered to do so.

Morrissey Boulevard will be closed for parts of the day, starting at 9 a.m., according to the state's Department of Conservation and Recreation.

Emergency management officials are gearing up for "a strong/long duration coastal storm" expected to bash the Bay State beginning late Thursday night and lasting through Saturday. Some areas of the state could see as much as five inches of rain and the Massachusetts Emergency Management Agency has warned of "major — and potentially life-threatening — coastal flooding."

"People should take this really seriously, irrespective of what it looks like out there today," Baker said Thursday afternoon.

Speaking at a press conference while Lt. Gov. Karyn Polito held a conference call to coordinate with municipal emergency management officials, Baker said that the flooding expected with the coming storm will be worse than the storm on Jan. 4, which flooded large swaths of Boston's Seaport District, shut down some MBTA service and sent dumpsters floating down city streets.

"We're expecting to see more severe flooding issues here than we saw in the Jan. 4 storm," the governor told reporters. "That means some roads in downtown Boston and roads along the coast that usually have flooding issues will likely become impassable for some time. For example, certain sections of the Seaport District and the North End and Morrissey Boulevard will likely flood for some period of time Friday."

Transportation Secretary Stephanie Pollack said the T was placing sandbags at Aquarium Station, the downtown Boston Blue Line station which flooded and was closed in January.

The Boston Water and Sewer Commission spent Thursday clearing catch basins and storm drains throughout the city, but especially in areas that were flooded in January. Boston Mayor Martin Walsh said employers should consider that workers will have to commute through the storm twice on Friday.

"I encourage all residents to be mindful of the storm and encourage employers to take the weather into consideration, which will mostly impact the coastal areas of our city," Walsh said in a statement. "As we saw with the coastal flooding in the Seaport in January, there is a need to proactively plan for our changing climate."

Deanna Moran from the Conservation Law Foundation echoed Walsh's point and said the fact that downtown Boston is preparing for a significant flooding event less than two months after the most recent one suggests that shutting down parts of the city due to flooding could become a common occurrence.

"It's no longer an infrequent event and climate change is exacerbating the impacts of these storms more and more," Moran, CLF Massachusetts' director of environmental planning, said. "What we will see (Friday) is definitely a preview of what could be the new normal because of climate change."

The expected flooding will be fueled not just by several inches of rain, but also by a storm surge that will overlap with three astronomically high tides -- Friday at 11:15 a.m., Friday at 11:45 p.m. and Saturday at 12:05 p.m, in Boston.

"Tides will be astronomically high during the first few days of March. There is a substantial risk for moderate to major -- and potentially life-threatening -- coastal flooding along ocean-exposed portions of the eastern Massachusetts coast over multiple high tide cycles due to potential for a persistent and strong onshore E/NE wind," MEMA wrote in a preparedness update Thursday. "The late morning to midday Friday high tide, the Friday night high tide, and the Saturday midday high tide, remain the high tides of greatest concern, although following high tides could also present problems depending on how well the tides are able to go out."

In Duxbury among other communities, local fire officials asked residents who live in flood zones to voluntarily evacuate their homes during high tides Friday and Saturday, and MEMA expects that communities along the coast from Salisbury/Newburyport to Plymouth "may require evacuations" as a preliminary storm surge of 3 to 3.5 feet contributes to waves up to 30 feet just offshore.

"I can't stress this enough -- this isn't a snowstorm in eastern Mass. but the storm itself, especially along the coast, is shaping up to be more severe than the storm on January 4," Baker said. "While crews were able to perform rescues in between high tide cycles in January, it's possible that first responders will be unable to reach all flooded areas at peak high tide tomorrow."

Baker said Thursday he does not expect to tell executive branch employees to stay home on Friday and would prefer not to order mandatory evacuations. He said "many" towns along the coast are considering evacuation orders.

"Our goal here is to nudge people as hard as we can to make the right kind of calls," he said while urging people who live in areas that flooded in January to "expect it will be worse and prepare for that."

He added, "If you live in an area that is told to evacuate, we strongly encourage you to do that first thing Friday morning. Many folks may not be able to return until late Saturday or maybe even Sunday. That means people should plan for medicine, clothing, food, money and pets."

Massachusetts National Guard Adjutant General Gary Keefe said about 200 soldiers and airmen will be activated to respond to the storm. They will be stationed with tactical vehicles around the state in locations that are expected to flood Friday and Saturday. The National Guard's main charge is to conduct high water rescues, Keefe said.

In addition to the concern about flooding, the National Weather Service on Thursday warned of damaging hurricane-force wind gusts on Cape Cod and the Islands, the possibility for heavy, wet snow and power outages at higher elevations, and flooding of some bodies of fresh water in the eastern part of Massachusetts.

"We are obviously no strangers to difficult and unexpected weather and we fully expect the next 48 hours to be particularly challenging along the coast," Baker said.