Although much of the East Coast of the U.S. was hammered by a massive winter storm, the dire predictions of "historic" snowfalls in some areas, particularly New York City and Philadelphia, failed to materialize, prompting criticism of meteorologists and public officials.

One forecaster at the U.S. National Weather Service, which called the storm a "crippling and potentially historic blizzard," drew attention for taking to Twitter to say sorry. 

"My deepest apologies to many key decision-makers and so many members of the public," wrote Gary Szatkowski, the
meteorologist in charge of the organization's office in Mount Holly, N.J. "You made a lot of tough decisions expecting us to get it right, and we didn’t. Once again, I'm sorry."

A Facebook page from the U.S. National Weather Service acknowledged that there was much less snow than predicted in their forecasts.

"The science of forecasting storms, while continually improving, still can be subject to error, especially if we're on the edge of the heavy precipitation shield," the statement said. "Efforts, including research, are already underway to more easily communicate that forecast uncertainty."

Computer models

The storm tracked further east than forecasters expected, sparing some areas but dumping heaps of snow in Boston and New England. The Maritimes also received heavy snow and blizzard conditions  

"There is still a lot of complexity and it is still an imperfect science," said Peter Kimbell, warning preparedness meteorologist at Environment Canada. 

However, he rejected the notion that forecasters get the weather wrong most of the time. 

"We actually get it right a lot of the time," he said. "And it all depends on your perspective of what getting it right is.
If we say we're going to get 15 centimetres of snow and we get 12, is that good or not good?"

While Philadelphia, New York and New Jersey had braced for 30 to 60 centimetres of snow, they got far less than that. New York City received about 20 centimetres, Philadelphia a mere 2.5 centimetres or so. New Jersey got up to 20 centimetres.​ 

On the other hand, Massachusetts and Connecticut were some of the hardest hit areas with as much as 60 centimetres of snow. 

Boston could receive up to 64 centimetres of accumulation, approaching the record of 69.85 cm set in February 2003.

A blizzard warning remained in effect for much of Massachusetts and Rhode Island, where snow was expected to fall throughout the day at a rate as high as five to eight centimetres an hour.

'Not as complex as the atmosphere'

Forecasters rely on measurements taken from a variety of locations both on and offshore, including surface stations, weather balloons and buoys off the coast, as well as information obtained from radar and satellites. 

The data, which includes temperature, wind speed, barometric pressure and wave height, are fed into computer models that predict what conditions will likely be. Forecasters also will compare the outcomes from a variety of different models to get a more accurate prediction. 

Part of the problem, meteorologists say, is that there is just not enough initial data because it is impossible to have sensors to gather data in every part of the atmosphere. It is ultimately an incomplete picture of the conditions.

"So, basically there are holes in these measurements because we don't have surface measurements everywhere," said Ian Folkins, from the department of physics and atmospheric science at Dalhousie University in Halifax.

The discrepancy between what can be measured and put into the model, and the current conditions everywhere on the planet creates distortions in the forecast the further out it predicts.

"The forecast model is not as complex as the atmosphere," said CBC metereologist Jay Scotland. 

Kimbell said forecasts are also continually improving as the models become more complex. 

"Our four-day forecast today is as good as a three-day forecast was 10 years ago," he said. 

'Rock and a hard place'

Kimbell said meteorologists at Environment Canada have the leeway to err on the side of caution, particularly when issuing warnings when public safety is at stake. 

"It's better to say there is going to be a bad storm and save lives than to minimize it and be wrong on the other side and actually it's worse and the impacts are severe," he said. 

For instance, he said the weather agency might issue a snowfall warning in Toronto for the city's first winter storm if conditions are just below the threshold that would normally trigger the alert. This will signal to drivers, some of whom may be still getting used to driving in the snow, that they should be careful. 

Officials in New York and New Jersey Tuesday defended their decisions to shutter public transit and close roads ahead of the storm once it became clear that some areas were largely spared.

"I would rather, if there is a lean one way or another, lean towards safety because I have seen the consequences the other way and it gets very frightening very quickly," said New York Gov. Andrew Cuomo. 

Scotland said forecasters cannot always err on the side of caution, because if they do people may start to take warnings of dangerous conditions less seriously in the future. 

"They are kind of caught between a rock and hard place," he said. 

With files from The Associated Press, Reuters