Why Your Local Weather Forecast Is Going To Get Better

Jun 13, 2019

The U.S. government is juicing up its weather forecasting power.

This week, the National Oceanic and Atmospheric Administration announced that it has upgraded its main weather forecasting model, called the Global Forecast System.

"Virtually any aspect of the weather forecast — whether it is temperature or precipitation — will see overall improvement with this upgrade," Brian Gross, director of the Environmental Modeling Center at the National Weather Service, said during a conference call with reporters.

NOAA scientists say the new system will also be better at predicting major weather events such as hurricanes by more accurately predicting a storm's path and intensity.

To make such improvements, NOAA's Global Forecast System is getting a new engine, or "dynamical core," called the Finite-Volume Cubed-Sphere.

And it's been a very long time since they changed that engine: "Today's implementation of the GFS marks the first major upgrade to the GFS dynamical core in nearly 40 years," acting NOAA Administrator Neil Jacobs told reporters.

The engine is the part of the model that "computes wind and air pressure for successful numerical weather prediction," NOAA says.

For years, there's been broad agreement that the U.S. weather forecasting system needed an upgrade. "Over the years, the National Weather Service has fallen behind its European counterparts in the accuracy of its forecasts," meteorologist Jason Samenow told NPR in 2015.

That was particularly apparent in the lead-up to Hurricane Sandy in 2012. "The European model was the first to accurately predict that Sandy, rather than hooking out to sea, would actually strike the U.S.," Samenow said.

After that devastating storm, Congress approved NOAA funding to, as NOAA put it, "dramatically improve U.S. hurricane forecasting and develop a forecast system that would be second to none."

NOAA has been running the new engine for the past three years of weather to compare its forecasting power to the model it had been using.

The improved accuracy is clear in several side-by side examples provided by NOAA. For example, during the powerful winter storm in January 2018 that became known as a "bomb cyclone," the model in use at the time indicated a much lighter day of snowfall in the upper Northeast U.S. than what actually happened. The updated model was more accurate — it showed heavy snowfall.

The side-by-side examples also show that the old model inaccurately predicted "extreme strengthening" of Hurricane Florence last year, while the updated model was much more accurate at predicting its path and intensity.

The old model will continue to run in parallel through September to compare the predictions.

This new model has faced delays in its rollout. As The Washington Post reported, it had been planned for early this year, but the National Weather Service said the model had a few technical issues. And the partial government shutdown also slowed things down.

The information supplied by the new forecast model will be used in local forecasts across the United States.

"The weather forecasts that you hear are provided by National Weather Service forecasters, or folks that are using the numerical guidance that our numerical models provide to them," Gross said. "So we're really looking at improvements in this foundational information that the individuals that forecast the weather use on a day-to-day basis."

There's also another reason the forecasts are expected to improve. Over the past several years, NASA has been launching new satellites that collect "advanced imagery and atmospheric measurements of Earth's weather."

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