Forecasts improve under the radar, firm reports
degree better than the 5-day forecasts of 11 years ago.
Forecasters can predict winter storms 22 hours ahead of time, up from 17 hours in 2005.
Forecasters have predicted some dangerous extreme events coming about a week ahead of time, including Superstorm Sandy in 2012, 20 inches of rain in South Carolina in 2015 and a 2016 East Coast blizzard, in ways they could never have done before.
When it comes to parsing where it’s going to snow instead of just rain or sleet, things get trickier. And when that line between snow and rain moves by only a couple dozen miles it can make a huge difference.
That was an issue after last winter’s blizzard, when New York and New Jersey officials blasted the weather service for not dialing back on forecasts of a giant snowfall that ended up occurring further west.
Problems with that forecast were compounded by the way the storm’s uncertainties were communicated to the public — or in this case not — meteorologists said.
Meteorologists mostly credit their increasing accuracy to complex, high-resolution computer models that take in giant amounts of real-world data from satellites and elsewhere and use physics formulas to crunch out countless simulations of what’s going to happen next. As those are compared, cross-referenced and run again, a clearer picture of future weather emerges.
Louis Uccellini , now director of the National Weather Service, recalled that 40 years ago he and colleagues at NASA celebrated when their computers hit the 1 million calculations per second mark. In about a year, the weather service forecast will be about 4 billion times faster, he said.