Since Sunday, the weather service had predicted anywhere from 18 inches to 3 feet of snow for New York, holding out the possibility that a “historic blizzard” was about to strike the largest city in the U.S.

So what went wrong?

Weather Service forecasters conferred with the Weather Prediction Center in Maryland in several conference calls as the storm approached. Stark said the forecasts that came out of those calls were based partially on the models that were showing the storm taking a closer track to the coastline, as well as on human consensus.

Difficult Predictions

When it comes to a large winter storm moving up the Atlantic coast, predicting how much snow will fall on its western edge can be particularly difficult because that is where precipitation amounts can fall off rapidly, said Louis Uccellini, director of the weather service. Snowfall amounts can change a lot over short distances, he said.

“What we learned from this storm is that we all need to improve on how we communicate forecast uncertainty,” Uccellini said in a conference call with reporters.

He said the weather service would be reviewing many of its procedures.

The European Centre for Medium-Range Weather Forecasts model was very bullish on the storm, while the U.S. Global Forecast System model had the storm forming farther to the east and didn’t have as much enthusiasm when it came to snow totals, said Rob Carolan, a meteorologist with Hometown Forecast Services Inc. in Nashua, New Hampshire.

Weather Models

“Everyone went with the Euro and it was wrong,” Carolan said. “This winter the Euro hasn’t been the model it has been in the last two winters.”

While the GFS, which was upgraded earlier this month, did a better job forecasting how the storm played out, another U.S. model also erred on large snowfall amounts, Uccellini said.

“Our own NAM model was right there with the European Centre,” he said.

Blizzard forecasts prompted New York City and state officials to shut roads and commuter transit systems and trans-Hudson crossings, including the Lincoln and Holland tunnels, and the George Washington Bridge. Amtrak cut back on service along its Northeast corridor.

New York Governor Andrew Cuomo issued a travel ban on downstate roads; New Jersey Governor Chris Christie and Connecticut Governor Dannel Malloy did so as well. At least 7,517 flights were canceled on Monday and Tuesday in the U.S., according to FlightAware, a Houston-based airline tracking service.

Uccellini said elected officials made the right call and their actions may have saved lives. The storm did have a major impact on New England, particularly along the Massachusetts coast, where there was flooding along with the snow, he said.

’Knife Edge’

“New York was on the knife edge of the dry side,” said Richard Bann, a meteorologist with the U.S. Weather Prediction Center in College Park, Maryland. “Obviously, if you go a short distance east in Connecticut, they will tell you a different story.”

In the end, the storm was too far out in the Atlantic to deliver the blizzard and bands of heavy snow across New York City. Overnight, forecasters knew the storm wasn’t going to be as severe in New York as first predicted and the revisions started.

Across New England, snow fell by the foot. As of 3 p.m., Boston reported 26 inches downtown and 20.8 inches at Logan International Airport. Wind gusts reaching 75 miles per hour were reported across Cape Cod.

“I think what happens is the philosophy behind weather forecasting is that everyone in this business is in it because they want to experience the big storms,” Carolan said. “They start to wishcast, they lose sight of what is going on in the atmosphere.”

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