On Friday and Saturday, a powerful storm will lash the Northeast with destructive coastal flooding, wind and heavy snow. It is shaping up to be the most destructive nor’easter of the season, perhaps the most destructive in decades for some along the coast.

The coastal flooding could be worse than what New England experienced during the “bomb cyclone” in early January. Storm surge in eastern Massachusetts seems likely to match or exceed the levels of the early January storm as well as the Blizzard of 1978. With a massive, damaging wind field, it will mimic the impact of Hurricane Sandy in 2012.

The National Weather Service is calling it a life and death situation along the coast.

The flooding

The timing of this nor’easter could not be worse. It coincides with the full moon, when tides are at their highest. Coastal flooding already began Thursday morning because of high tide alone. On Friday and Saturday, 3 to 5 feet of storm surge will be added to the tides. There will also be extra inundation from waves, which are expected to reach a height of 30 feet offshore.

Major flooding is all but certain in the Northeast over the next couple of days. Shoreline roads will be flooded — some with more than three feet of water — and largely impassable. Large debris will be washed ashore. Basements will flood, sea walls could be damaged, and beaches will be severely eroded, the National Weather Service predicts.

Southern New England will bear the brunt of the coastal flooding, with onshore winds forecast to last through at least Saturday evening.

In Boston, major flooding could begin as early as Friday morning. The storm will last through three tide cycles: noon Friday, midnight Saturday and noon Saturday. Although water levels could recede between tides, some level of coastal flooding is likely through the storm’s duration.

Farther south on the coast, flooding will begin on Long Island Friday morning with 1 to 2 feet of floodwater above ground along the coast. During high tides, 2 to 3 feet of water is possible above ground level. “This would result in numerous road closures and cause widespread flooding of low lying property including parking lots, parks, lawns and homes/businesses with basements near the waterfront,” the Weather Service warned. “Vehicles parked in vulnerable areas near the waterfront would become flooded.”

In New Jersey, coastal flooding could become major through four high-tide cycles from Friday morning through Saturday evening.

The wind

The duration and intensity of this storm’s wind has meteorologists comparing it to Hurricane Sandy. Some computer models are predicting wind gusts to top 70 mph in the Northeast, and will come close to, if not surpass, 60 mph as far south as the Washington-Baltimore region.

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As the nor’easter strengthens off the coast, cold high pressure will also be building to the north. Instead of tracking up the East Coast and then out to sea like nor’easters typically do, the high pressure will act to block the storm and slow it down, lengthening the duration of impact. The high pressure will also compress the northwest side of the storm. The compression is what will create such high wind speeds.

The winds will be damaging and will lead to power outages from the Mid-Atlantic to New England. Trees will come down on roads and will block access. Driving will be difficult, especially in high-profile vehicles, and bridges are likely to close during the peak of the storm. Flights into and out of the Northeast will be delayed if not canceled because of the high wind.

The snow

To be clear, the snow seems like the least of this storm’s problems. Still, accumulation could exceed two feet in high elevations, and along the coast where winds are strong, visibility could be drastically reduced.

The heaviest snow will be focused on Upstate New York, Massachusetts and Connecticut, spreading from west to east starting Thursday night. Depending on how the storm evolves and how cold it gets, the Boston and New York City areas could end up with four inches through Friday night.

Snow will accumulate as far south as the Washington region and down the spine of the Appalachian Mountains.

Snow forecast

Boston — 2-4 inches

Springfield, Mass. — 3-6 inches

New York City — 2-4 inches

Philadelphia — 1-3 inches

Washington — No major accumulation likely