Weather models got it right this time

As advertised, the Blizzard of 2016 was a crippler. But it was the forecasts, themselves, that put the region into shutdown mode and turned Saturday into a snow day long before the first flake was sighted.

Those often-squabbling and maligned computer weather models - blamed for legendary snow busts - had a blockbuster week, seeing the possibility of this East Coast megastorm a full seven days ago.

The models were consistent, "run after run, day after day," Daniel Petersen, meteorologist with the government's Weather Prediction Center, said Saturday.

His boss, Louis W. Uccellini, a winter-storm expert and director of the National Weather Service, said he could not recall such agreement among global models in his entire career.

The quality of models, run by the European Community, the United Kingdom, and the United States, depends on the quality of observations, and those have improved with satellite and air reconnaissance, said Petersen.

Every six hours, observations are taken to capture "initial conditions," and the models attempt to simulate how conditions will change in six-hour increments.

The atmosphere, a 10-mile-deep fluid attached to a sphere spinning at 1,000 m.p.h., is imperfectly observed.

This time the models weren't perfect. For example, they underrated the northern extent of the snow, said NBC10 meteorologist Glenn Schwartz.

Still, they were right about major features, such as an axis of heavier snow just west of the Washington-Philadelphia corridor.

Said Petersen, "That's quite a feat."

twood@phillynews.com 610-313-8210 @woodt15