14 January 2015

Weather Forecasts Are About To Get Even Better

Posted by Dan Satterfield

gfsgraphicI asked one of my professors at OU in the mid 1970’s if we would ever be able to make reliable forecasts out to a week, and he said it was unlikely, because we would needs computers running hundreds of times faster than they did then.

Well, what do you know! The computer in your iPhone is  thousands of times faster than what was in the Lunar Module on July 20, 1969.

output from the upgraded GFS model today showing winds and vorticity at the 500 millibar level for next week.

output from the upgraded GFS model today showing winds and vorticity at the 500 millibar level for next week.

Make that thousands, and we do a pretty good job with a 7 day forecast now more reliable than a 3 day forecast was in the 1970’s! Numerical weather prediction using models with simulations of the atmosphere and using the laws of physics have made it possible, but some folks have better computers than others. The European Center for Medium Range Weather Forecasting (ECMWF) in London has been running probably the best global weather model out beyond ten days for a few years now (the ECMWF Model). Synoptic weather forecasters like myself rely on it greatly, and it did a much better job with Hurricane Sandy than did the US Global Forecast System (GFS) model.

The U.S. is finally beginning to catch up though,. and today was a red-letter day with the GFS model being upgraded to a much higher resolution. I’ve been looking and using the experimental runs of this new GFS for a few months now, and I can tell you it is much better. This will definitely improve weather forecasts around the world.

Here are some selected snippets of a press release from NOAA about it.

 “These supercomputing upgrades will significantly improve our ability to translate data into actionable information, which in turn will lead to more timely, accurate, and reliable forecasts.”

Ahead of this upgrade, each of the two operational supercomputers will first more than triple their current capacity later this month (to at least 0.776 petaflops for a total capacity of 1.552 petaflops). With this larger capacity, NOAA’s National Weather Service in January will begin running an upgraded version of theGlobal Forecast System (GFS) with greater resolution that extends further out in time – the new GFS will increase resolution from 27km to 13km out to 10 days and 55km to 33km for 11 to 16 days. In addition, theGlobal Ensemble Forecast System (GEFS) will be upgraded by increasing the number of vertical levels from 42 to 64 and increasing the horizontal resolution from 55km to 27km out to eight days and 70km to 33km from days nine to 16.

Computing capacity upgrades scheduled for this month and later this year are part of ongoing computing and modeling upgrades that began in July 2013. NOAA’s National Weather Service has upgraded existing models – such as the Hurricane Weather Research and Forecasting model, which did exceptionally well this hurricane season, including for Hurricane Arthur which struck North Carolina. And NOAA’s National Weather Service has operationalized the widely acclaimed High-Resolution Rapid Refresh model, which delivers 15-hour numerical forecasts every hour of the day.