International Elevated Thought Conference

Environment      Sept. -17'



  Aug. 2017


  Sept. 2017






Hurricane Irma again demonstrated the inferiority of the top U.S. weather model




The National Hurricane Center accurately predicted the path of Hurricane Irma, which struck southwest Florida on Sept. 8. This was not an easy storm to forecast, though, as computer models disagreed with one another on important details right up until landfall.


But in general, the European model, which is run by the European Center for Medium-range Weather Forecasting (ECMWF), performed far better than the premiere U.S. model, known as the Global Forecast System (GFS).


Hurricane Irma is one more in a long line of storms to shine a spotlight on problems with the GFS, particularly at intermediate to longer timescales. The issue gained prominence after Hurricane Sandy struck New Jersey in October 2012, which the European model hinted at at least a week in advance. The GFS model, however, didn't catch on to the storm's unusual track until about 5 days in advance.


Given weather's sizable influence on the economy, the growing gap between the reliability of non-U.S. weather models and their international competitors could put billions of people at risk.


Critics of the GFS say it needs to be improved with greater computer processing power. In addition, they say, the model needs to process weather information in more advanced ways, with greater resolution in both the horizontal and vertical scale, since the weather on the surface depends heavily on what is going on in the mid-to-upper atmosphere.


The National Weather Service is aware that it's running behind in the so-called weather modeling wars, and the agency is touting recent improvements as well as planned changes set to take place in the next few years.






















Michael Farrar, who heads the Environmental Modeling Center (EMC), which is the lead office within the National Oceanic and Atmospheric Administration (NOAA) that develops and operates computer models, said "it’s no secret” that the GFS has been behind the competition.


"While it’s continued to improve remarkably over time... it’s consistently behind the European model," Farrar said in an interview.


He pointed out that the GFS accurately predicted the movement of Hurricane Harvey, which devastated the Houston area with the most extreme rainstorm in U.S. history, but that the forecasts for Irma were less reliable.


Still, he cautioned that the European model, too, missed the eventual track the storm took, which was just inland in southern Florida.


“Even the European model has got its issues,” Farrar said.


No computer model or human forecaster got Hurricane Irma exactly right. Forecasters relied heavily on ensemble forecasting to gauge the storm's threat to the U.S. well in advance. Such forecasting involves running a computer model numerous times while varying the initial conditions slightly each time.


Ensembles can help reveal how uncertain a forecast is, since if a storm's track is extremely sensitive to small changes in initial conditions, that is usually an indication of greater uncertainty. Ensemble forecasting can also help compensate for model weaknesses or biases.


The weather model wars are not an issue only for meteorologists and weather geeks to be concerned with. With high impact events, like a blizzard or a hurricane like Irma, lives are on the line, as well as big time dollars.


International Elevated Thought Conference 2017

International Elevated Thought Conference 2017