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NOAA upgrades the GFS weather model to improve forecasts

Published: Mar. 22, 2021 at 4:40 PM EDT|Updated: Mar. 23, 2021 at 6:38 PM EDT
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TALLAHASSEE, Fla. (WCTV) - A newer version of the American Global Forecasting Model, or GFS, went live Monday morning, according to NOAA. The federal agency said Monday that there was improvement in precipitation, temperature and hurricane forecasting compared to the older version, and improvement in the accuracy of extreme weather events.

The newer version, announced in 2019, was compared with “replacing the engine of a car,” Dr. Louis W. Uccellini, the director of the National Weather Service, said in a media conference call Monday afternoon.

“With today’s upgrade, we are adding more horsepower to [the] engine and more upgrades to the car as we move forward,” Uccellini said, later suggesting more work to the way the model ingests weather data to create a model output.

NOAA gave the 16th version of the global model praise during the conference call noting it’s improved performance with hurricane, extreme weather, as well as day-to-day forecasting.

“The improvements are pretty significant with this upgrade,” Dr. Vijay Tallapragada, the Chief of the Modeling and Data Assimilation Branch of NOAA’s Environmental Modeling Center, said in the media conference call.

There was a 10% to 15% improvement in tropical cyclone track and intensity forecast, Tallapragada said. There was also longer lead times as much as 36 hours, and reduced bias in the model.

Tallapragada also noted improvements in the accuracy of lower-level temperatures as well as winter weather and rainfall predictions. The chief modeler said that the predictions with the recent snow storm in Colorado were better with the newer and now operational version compared to the older one.

The model’s improvements included upgraded model physics, and an increase in the vertical resolution of the model from its previous 55 kilometers to 80 kilometers (from 34 to 50 miles). The increased height of the model’s domain would allow for better prediction of the stratospheric polar vortex, and latent heat release’s impacts on a weather system.

The upgrades come as the European Centre for Medium-Range Weather Forecasts’ model, or colloquially known in the weather community as “the Euro,” has fame for being more accurate than the American GFS (a little more detail can be found here). The European model isn’t always right, but Uccellini admitted that they still have some work to do - even with the new update - and said that the model across the Atlantic is still “leading the pack.”

“We are catching up, I believe,” Uccellini said.

The “next big task” is to update the data assimilation, Uccellini said. Data assimilation brings in weather data into the forecast model such as surface observations and satellite data so that it can create a forecast. Without the starting point data, it’s hard to put a forecast together. If the data is bad, then it leads to a bad forecast (think “garbage in, garbage out”). After the model update, NOAA wants to improve the way data is ingested into the model to allow for more data to enter.

“This effort will allow the model to ingest more data from geostationary and polar-orbiting satellites, as well as flight-level wind, temperature and moisture observations from aircraft,” according to NOAA’s press release.

The better forecasts from the global model would assist weather forecasters, such as those in the Pinpoint Weather Team, with providing a more accurate forecast and better lead times with tropical and severe weather.

The supercomputers that will be running the newer version are located in Reston, Va. and Orlando, Fla., Uccellini said. The computers were said to be among the 30 fastest in the world and would have a combined computing power of 8.4 petaflops, according to a 2018 press release. That power is equivalent to running 150 Apple Mac Pro computers or 700 XBox Series X gaming consoles together simultaneously.

This story was updated to add the on-air version of this story with more detail on how weather models work.

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