Computer model is a best guess, not very reliable 10 days out.
WILMINGTON, Del. — The story of a mega snowstorm on the horizon started with a long-range winter weather model and a social media post suggesting that 10 days from now, the Middle Atlantic will get a snow blast measured in feet, not inches.
Only trouble is it's nearly impossible to predict snowfall 10 days out, said Gary Szatkowski, meteorologist in charge at the National Weather Service in Mount Holly, N.J.
"It's a little surprising that people are falling for this," Szatkowski said.
But they are, and all day Thursday the service was explaining to emergency planners throughout the region that no one has a reliable forecast for any weather 10 days out, especially when conditions are constantly changing.
Typically, forecasters have a pretty good feel for snow events a few days out, Szatkowski said. Any more lead time and it gets tricky.
So where did the trouble start?
The weather service typically does seven-day forecasts but produces weather maps using models that take a longer view, Szatkowski said. The model is helpful to look at trends in the region.
Someone took one of the maps from the model, a map that showed feet of snow for the Middle Atlantic, and posted it on social media.
"People now have taken off and run with it," Szatkowski said. "We can't forecast this 10 days out. The people who did this were really irresponsible."
No one is sure who started the snow frenzy.
Szatkowski said people quickly bought into the hype because emergency planners are paid to pay attention to dramatic weather events and other folks are really fed up with this winter's weather are are fretting about more snow and cold.
At the Delaware Department of Transportation, where officials are no strangers to what happens when wrong information gets out on social media, the key is giving people answers, spokesman James Westhoff said.
During Superstorm Sandy, a Facebook post said the new, multimillion dollar, Indian River Inlet Bridge had collapsed.
Officials didn't address it right away and the rumor grew, Westhoff said. But soon after, a single-line Facebook post let folks know the bridge hadn't collapsed.
Transportation officials were among the many who heard Thursday about the alleged mega storm.
"We will all be watching the forecast in the coming days," Westhoff said. Meanwhile, crews in Delaware started restocking salt supplies and making repairs to damaged equipment, steps they would be taking regardless of any future forecast.
"If there is a major event in 8, 9 or 10 days, we will be ready," he said.
One of the tweets that started the nail gnashing pulled an image from a computer model that predicted conditions 10 days from Wednesday, a model that changes each time the program is run.