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Here's What Caused Those Big High Tides During The Nor'easter

A car sits in floodwaters from Boston Harbor on Long Wharf in Boston.
 (Michael Dwyer/AP)MoreCloseclosemore
A car sits in floodwaters from Boston Harbor on Long Wharf in Boston. (Michael Dwyer/AP)

Thursday afternoon saw some of the highest tides parts of Massachusetts, New Hampshire and Maine have seen since the Blizzard of 1978, which occurred Feb. 6 and 7 of that year.

A combination of factors was behind the excessive tides.

First, there were astronomically high tides caused by the moon, which is just past full, and the storm itself. The level of high tide fluctuates every 12 hours, and each month there are a few high tides that are the highest in the cycle.

Today's storm coincided with those high tides.

The highest tides of the month occurred during this storm. (Courtesy Tides and Harbors)
The highest tides of the month occurred during this storm. (Courtesy Tides and Harbors)

The storm, although it was about 100 miles off Nantucket, had very strong onshore winds blowing the water toward the coastline. The rapid intensification created a lot of wind, which blows the water toward the shore. Add in some big waves, and you have additional water heading for the shoreline.

The tightly packed isobars, black lines, indicate strong winds around this storm. (Courtesy NOAA)
The tightly packed isobars, black lines, indicate strong winds around this storm. (Courtesy NOAA)

Finally, there has been a rise in sea level over the past 100 years.

While this rise is slow, the combination of a very high monthly tide, a big storm and sea levels a bit higher likely all contributed to battering the coastline with one of the highest tides since the Blizzard of 1978 nearly 40 years ago.

The high tides during the blizzard of 1978 stand out as the highest on record in Boston Harbor. (Courtesy NOAA)
The high tides during the blizzard of 1978 stand out as the highest on record in Boston Harbor. (Courtesy NOAA)

Related:

David Epstein Twitter Meteorologist
David Epstein is WBUR's meteorologist.

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