What was Superstorm Sandy?

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Sandy as it changed from a hurricane to a massive post-tropical cyclone.

One year ago today a storm named “Sandy” slammed the east coast of the U.S. while also delivering a powerful punch hundreds of miles inland. The effects of Sandy could be seen here as waves on Lake Michigan soared to over 21 feet!

What was Sandy and what made it so unique? As you read on you’ll find those questions do not have simple answers.

Sandy began as a tropical depression in the Caribbean Sea one week before its final landfall. It strengthened to a Tropical Storm later that day and continued its growth spurt becoming a major hurricane (category 3) when it swept across Cuba 3 days later.

Meteorologists kept an eye on Sandy as it fluctuated in strength the next 2 days even weakening to a tropical storm. But the big story with Sandy wasn’t so much the winds at its core like typical hurricane. Sandy’s oncoming furry would be a result of overall size and strange path.

As Sandy headed north, up the east coast it regained some strength. Now, a hurricane passing off the coast of North Carolina in fall is about as common as the Packers beating the Vikings. It’s pretty much going to happened once or twice a year. But as Sandy headed north it ran into a road block. High pressure over Greenland redirected Sandy.

The unique path of Sandy contributed to the large amount of damage it caused.

The unique path of Sandy contributed to the large amount of damage it caused.

Instead of the storm drifting into the middle of the northern Atlantic as nearly every hurricane on the same path ends up doing, the Greenland high twisted the jetstream to the northwest. Once Sandy moved close enough, the jetstream would grab the storm and pull it into the Jersey coast.

Back on land more trouble was brewing. A cold front had stalled across the Appalachian Mountains. As Sandy approached shore, the chilly air behind the front became entangled in Sandy’s winds. The intrusion of cold air meant Sandy was now feeding off the contrast of colliding warm and cold air instead of getting its energy solely from warm ocean water.

Sandy was now a hybrid storm, not a hurricane, not a nor’easter, and certainly not a run of the mill mid latitude cyclone. It’s hard to peg an accurate moniker for Sandy, though the not so sensational “post-tropical cyclone Sandy” would be the most accurate.

Sandy came on shore with winds up to 80 mph. By comparison, the winds in Hurricane Katrina were around 50mph faster. Hurricane Andrew’s winds brought twice the velocity to south Florida 20 years earlier. But the immense size of Sandy meant its gusts were pummeling nearly everyone with an ocean front view from Virginia to Maine. Miles from shore the cold air wrapped into Sandy was producing snow in the mountains. The highest amounts in West Virginia reached over 3 feet!

The merging of Sandy with the jetstream trough and Appalachian front lead to one of the largest footprints we’ve ever seen from a weather system. Its evolution was not unlike the “Perfect Storm” in 1991. The biggest difference between the two was Sandy’s predecessor spent most of its energy on the open sea only delivering a glancing blow to the coast compared to Sandy’s direct hit.