WASHINGTON (AP) — The next time some nasty storms are heading your way, the National Weather Service says it will have a better forecast of just how close they could come to you.

The weather service on Tuesday started using a new high resolution computer model that officials say will dramatically improve forecasts for storms up to 15 hours in advance. It should better pinpoint where and when tornadoes, thunderstorms and blizzards are expected, so people could take cover.

“This will translate into lives saved and better decision-making on the part of the public,” said Geoffrey DiMego, branch chief of the weather service’s Environmental Modeling Center in College Park, Maryland. 

While day-to-day weather forecasts have improved in accuracy quite a bit over the years, detailed and accurate predictions of individual storms has still been a problem, he said.

The new computer model has four times more resolution and instead of updating every hour, it will update every 15 minutes. 

Until now, forecasts — not radar — would project storms as green blobs over half a state, such as northern New Jersey, said modeling center meteorologist Geoffrey Manikin. With the new computer model, “you can say there’s a good chance of a thunderstorm in Trenton or Morristown” so instead of a giant swath of green, the forecast shows circles of projected storms. Trenton is almost 50 miles south of Morristown.

The 15 hours in-advance forecasts will look more similar to radar images people watch as storms arrive, Manikin.

And it will be for the entire Lower 48 of the United States on “an almost neighborhood scale,” DiMego said.

While not a huge leap, this new model is “an important step” in making better forecasts, said Jeff Masters, meteorology chief for the private Weather Underground service.

Officials said two new supercomputers and five years of research make it possible for the upgrade in forecasts.

Online:

National Weather Service: http://www.weather.gov/