How the supermoon caused the perfect storm and record flooding
Posted January 5, 2018 12:29 a.m. EST
Updated January 5, 2018 2:07 p.m. EST
(CNN) — Call it the perfect storm.
The blizzard that battered New England on Thursday hit at just the right -- or wrong -- time, yielding record tides and frigid coastal flooding in several areas, including Boston, CNN forecasters said.
A combination of winds blowing ocean water onshore and a supermoon Monday resulted in the unprecedented flooding, the forecasters said.
The supermoon phenomenon occurs when the moon becomes full the same day it reaches its perigee, the point in its elliptical orbit closest to Earth.
And this week's supermoon definitely led to a higher tide, CNN meteorologist Jennifer Varian said. And the storm hit right as the tide -- already set to be the highest afternoon one of the month -- was rising.
Add rising sea levels due to melting ice sheets and glaciers, CNN meteorologist Brandon Miller said, and it was enough to push water over sea walls and into coastal New England streets.
Plus there was the bombogenesis, a weather process that occurs when atmospheric pressure dramatically drops 24 millibars in 24 hours. Thursday's was a double bombogenesis -- pressure dropped 59 millibars in 24 hours, rivaled only by a storm in 1989.
Throw it altogether, and you have a rare event that happens once every 25 to 30 years, according to the National Weather Service.
"We're not even talking about perfect as in the day of the week," CNN meteorologist Judson Jones said. "We're talking about the hours. This thing in nature was perfect."
The flooding was historic.
The tide gauge at Boston Harbor reached a record of 15.16 feet Thursday, according to the National Weather Service, beating the previous record of 15.1 set by the blizzard of 1978. The earlier storm left dozens of people dead, hundreds of homes destroyed and caused hundreds of millions of dollars in damage.
On Thursday, firefighters in Boston used rubber rescue boats to rescue dozens stranded by the freezing water pushing from the Atlantic Ocean.
Cars in some New England towns were partially submerged in about 3 feet of water and were also covered in a coat of snow and ice.
Massachusetts Gov. Charlie Baker deployed the National Guard when flooding was reported in about 32 communities across the state.
The weather service warned that it would take time for floodwaters to recede and that bitterly cold temperatures could then lead to freezing, resulting in ice-clogged drains.
Some roads could remain impassable for a couple of days, officials said.
Residents forced to flee homes
In Boston, firefighters carried a man away after his car became stranded in rising waters in an underpass, the Boston Fire Department tweeted.
Floodwaters came up to the doors of homes in Hull, Massachusetts, forcing some people to flee.
In one case, the fire department used a front loader to rescue a woman from the second floor of her house, photos from neighbor Jennifer Olivieri show.
Adam Abougalala told CNN he had "no heat, no electricity, no hot water" when floodwaters came into his basement in Revere, Massachusetts.
Water covered the wheel wells of cars for hours as the snow kept falling in his neighborhood.