Reality Check: U.S. Weather Prediction is Good, But Not the Best
For the first time, a "secret" among U.S. meteorologists became generally known to the general population: although very good, U.S. numerical weather prediction is no longer the best in the world. During the week and a half run up to the storm, it became obvious that the global forecasts of the European Center for Medium Range Weather Forecasting (ECMWF) were superior. Several days before the U.S. global model (the GFS), the ECMWF forecast model accurately forecast the path and intensity of the storm: a triumph of the technology. This superiority of the ECMWF was no fluke and in the subsequent months the media highlighted other cases where the U.S. model was inferior. But there was a silver lining to this revelation: the origins of the U.S. modeling problems
Miscommunication: A Hurricane By Any Other Name Can Still Be Devastating
A major communication snafu occurred with Sandy. As the storm approached the coast, it was losing its tropical characteristics and becoming more like a midlatitude storm (the fancy name for this is extratropical transition). So right before landfall, the National Weather Service downgraded Sandy to a post-tropical cyclone and responsibility for forecasting it was handed off to local Weather Service forecast offices. Hurricane watches and warnings were dropped, as one of the most dangerous storms of the century approached the Northeast coast. Keep in mind that the storm was still as strong as a hurricane, with maximum winds of 85 mph. And Sandy was much larger than the typical hurricane. The name change was terribly confusing to the media and many local authorities, some of which started to downplay the storm. Big mistake. The National Weather Service recognizes these problems in the post-storm review and has changed its strategy...next time the Hurricane Center will stay with such storms through landfall, and the warnings/watches will continue.
Will Storms Like Sandy Be More Frequent Under Global Warming? Probably NOT.
The media and politicians seem to believe something that is not true. That under global warming we can expect more storms like Sandy. Let me say this clearly: there is absolutely no reason to expect this.
First, consider the unusual track of Sandy. Most hurricanes turn right and move out to sea. The track of Sandy, a sharp left hook to the coast is nearly unprecedented during the past century. And it appears that the probability of taking such a left turn will become LESS PROBABLE under global warming. How do I know this? Professor Elizabeth Barnes and colleagues of Colorado State University have published a paper that analyzed the output of a large collection of climate models forced with increasing greenhouse gases. To quote from this paper:
"we demonstrate that climate models consistently project a decrease in the frequency and persistence of the westward flow that led to Sandy’s unprecedented track, implying that future atmospheric conditions are less likely than at present to propel storms westward into the coast."
Second, theoretical and modeling studies of the effects of global warming on hurricanes and tropical storms have determined that there will be no increase in the frequency of weaker hurricanes under global warming. Superstorm Sandy was a weaker hurricane (category 1) before landfall. So there is NO reason to expect more of such storms under global warming.
But the facts noted above have not stopped governors, mayors, newspapers, and the general media from repeating this canard, time and time again. Really frustrating! Global warming is a serious issue and society deserve facts, not baseless hype.
Announcement: Special Dinner and presentation (by me) on the storm that destroyed Ivar's Mukilteo landing restaurant in 2003. Where? When? At the rebuilt restaurant, next Thursday, November 7. More information here. Limited to 40 people.