A year later: How Sandy went from 'boring' to killer superstorm

Conditions conspired to create record girth, cause extensive damage

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Superstorm Sandy set several records and was unusual in even more ways. Here are 12 strange weather features of Sandy:

  1. SIZE: With tropical storm force winds that extended for 1,000 miles, Sandy was the largest Atlantic system on record. However, meteorologists only started recording this measurement for comparison in 1988.
  2. STORM SURGE: Sandy set historic maximum recorded water levels at the Battery in New York, Kings Point, N.Y.; Bergen Point, N.Y., Sandy Hook, N.J., Bridgeport, Conn., and New Haven, Conn., according to the National Oceanic and Atmospheric Administration.
  3. SNOW: This is the first time the National Hurricane Center ever listed snow or blizzard in their warnings. Three feet of snow fell in West Virginia.
  4. GREAT LAKES: It is unusual for 20-foot waves, large surges and tropical force winds to be recorded in the Great Lakes for a coastal tropical storm, but it happened with Sandy.
  5. ENERGY: NOAA’s Hurricane Research Division has an experiment program that measures integrated energy of a storm’s surge and waves on a 0 to 6.0 scale. Sandy reached 5.8, passing Katrina as the highest recorded so far.
  6. PRESSURE: A more established measurement of storm strength is barometric pressure, with the lower the pressure the stronger the storm. Sandy hit a low pressure of 945.5 mb in Atlantic City, which some federal agencies called the lowest pressure recorded north of the Mason-Dixon Line in the United States. The National Hurricane Center says the 1938 Great New England Hurricane, when reanalyzed, was slightly lower, but it was never recorded that low at the time.
  7. FORECAST: Computer models and forecasters saw Sandy coming for more than a week, even talking of a New York area landfall — an unusually accurate forecast.
  8. TURN WEST: It was the first time in modern recorded history that a storm took a sharp turn to the west and hit New Jersey. A scientific study said it was a once-in-700-years track.
  9. LANDFALL REPEAT: Sandy hit land in the very same town, Brigantine, N.J., as Irene did the year before (but Irene came from the south, a more common direction).
  10. FUEL: For a while Sandy was getting much of its fuel and power from the top of the system, which is more typical of a winter storm. Hurricanes tend to get their power from the warm water below.
  11. MISPLACED WINDS: Sandy’s strongest winds at one point weren’t in its eye but 100 miles west of its center, which meteorologists said is quite strange.
  12. NOTABLE S-NAMED STORM: This is only the second tropical system starting with an “S” to have its name retired, an indication of how unusual it is to have potent late-season storms and how busy 2012 was for Atlantic storms.

— Seth Borenstein, AP

WASHINGTON — It was the moment a run-of-the-mill hurricane mutated into a monster named Sandy.

Paradoxically, it was the same time Sandy lost much of its wind power, dropping from a hurricane to a tropical storm. It was a Friday night and Sandy had just passed the Bahamas and was being enveloped by an ordinary cold front coming off the Southeast. It was changing how it got its power, where its highest winds were and even what it looked like.

But mostly it was getting bigger. Dangerously large. And then it merged with a second storm, turned record huge and pivoted toward the nation's largest city.

It was that enormity that set off alarms in the people who knew weather, especially those living in the New York area. For a week forecasts placed Sandy on its path toward New York, and it was it sticking to it.

Months earlier, Princeton University professor Michael Oppenheimer had written a scientific study about the dangers of storms hitting the nation's largest city, and now he was watching one develop. He was enthralled but fearful, hoping that the forecasts would change.

"It was just this monster coming at us," he said.

Meteorological trade-in

In the year since Sandy blew through the East Coast, meteorologists have pored over forecasts, satellite photos, computer models, and even the physical damage to try to get a sense of what made Sandy the demon it was.

Put simply, what made the superstorm dangerous and freaky in more than a dozen different ways was a meteorological trade-in: The hurricane lost some oomph in winds in return for enormous size. And just like Katrina seven years earlier, Sandy caused so much havoc because of its record girth, National Hurricane Center Director Rick Knabb said, adding: "Smaller versions of those same storms would not have had the same scope of disasters."

Sandy's breadth pushed much more water into New Jersey and New York, dropped three feet of snow in West Virginia, caused 20 foot waves on the distant Great Lakes, and registered other records reflecting whopping energy. It meant at least 182 deaths and $65 billion in damage in the United States, the second costliest weather disaster in American history behind only Katrina, according to the National Oceanic and Atmospheric Administration.

"I don't know if we'll ever see another storm like this," said James Franklin, hurricane center chief forecaster. "The atmosphere can do a lot of weird stuff. I don't want more like this."

The question is, how likely is it that there will be more? Researchers continue to study whether Sandy was a forerunner of similar storms.

"One of the major lessons scientifically is that there could be these configurations of meteorological events that can combine to be very damaging in ways that are surprising," said NASA and Columbia University climatologist Cynthia Rosenzweig, who warned in a 2001 report of the kind of flooding that New York endured due to Sandy. She said other cities around the world have learned from New York's Sandy experience and are better preparing for flooding worsened by climate change and sea level.

A September study by NOAA found that global warming triggered sea level rise is making Sandy-type flooding more likely. For example, the flooding that swamped Sandy Hook, N.J., last year would have been considered a once-in-435-year event in 1950, but it is now a once-in-295-year event. By 2100, it could become a once-in-20-year event, the study said.

In the past century, sea level in the New York region has risen about a foot, two-thirds of it caused by man-made climate change, said Princeton's Oppenheimer.

The result? Fifty thousand people suffered flooding due to Sandy that wouldn't have happened if not for global warming, he said.

When things changed

Sandy wasn't always a big bully. For several days, this looked like a "kind of boring" hurricane, said NOAA meteorologist Ian Sears, who flew into the storm three times in a hurricane hunter airplane. Then came Friday night, nearly three days before landfall in New Jersey, when the cold front chugging west hooked up with the tropical system steaming north.

It wasn't a marriage of equals.

Sandy "was surrounded and absorbed as much as merged," Franklin said.

Suddenly, everything changed. Sandy wasn't getting its energy from warm water below like a normal hurricane, but being fueled from above. The strongest winds were about 100 miles to the west of the storm's center, something quite un-tropical.

That moment "was absolutely critical," said Jeff Masters, director of meteorology at Weather Underground and a former hurricane hunter meteorologist. "You had a wind field that more than doubled in less than one day. That's a huge amount of power to put in one storm."

Sandy kept growing. Its band of tropical storm force wind stretched for a record 1,000 miles, nearly the distance from New York to Orlando.

When Sandy combined with a second cold front, it regained some of its lost power. That's when Sandy went "from ginormous to mega-normous," said hurricane center specialist Eric Blake, who wrote the agency's final 157-page report on Sandy.