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Why hurricane forecasts have gotten much better — but could soon get worse

Hurricane Sandy is about to batter the East Coast and cause potentially billions of dollars in damage. That's... horrible news. But it's worth pausing for a second to note that those of us in the area who have stocked up on canned goods—or fled the storm's wrath—have also had days to prepare. And that's not a total fluke.

Well, at least we have advanced warning?

Hurricane forecasting, it turns out, has improved quite a bit over the past three decades. We haven't been able to stop massive storms from wreaking havoc on our cities and homes, but at least forecasters are getting better at telling us when to step out of the way.

Nate Silver wrote about some of the exciting new advances in weather forecasting in his book "The Signal and the Noise":

Perhaps the most impressive gains have been in hurricane forecasting. Just 25 years ago, when the National Hurricane Center tried to predict where a hurricane would hit three days in advance of landfall, it missed by an average of 350 miles. If Hurricane Isaac, which made its unpredictable path through the Gulf of Mexico last month, had occurred in the late 1980s, the center might have projected landfall anywhere from Houston to Tallahassee, canceling untold thousands of business deals, flights and picnics in between — and damaging its reputation when the hurricane zeroed in hundreds of miles away. Now the average miss is only about 100 miles.

Now, to be sure, this progress isn't totally uniform. Some hurricanes are more unpredictable than others, as MIT climatologist Kerry Emanuel told Andrew Revkin recently. What's more, predicting the intensity of a hurricane—as opposed to where it will land—remains quite difficult. The National Hurricane Center isn't much better predicting how powerful a hurricane will be when it makes landfall than it was back in 1990.

Still, the improvement in tracking hurricanes (see the chart on right) has been a major boon to public safety. In the case of Sandy, various computer models were converging last Friday on the likelihood that the massive storm would make landfall in Delaware on Monday afternoon. States like New York and New Jersey could declare emergencies and begin evacuations. 

Part of the reason for the improvement is that the computers used for climate modeling are getting ever more powerful. Time's Matt Peckham recently took a look at the National Center for Atmospheric Research's impressive new supercomputer. "All told, Yellowstone rates 30 times more powerful than its predecessor," he wrote. "To put that in context, NCAR says where Bluefire would take three hours to carry out an 'experimental short-term weather' forecast, Yellowstone might render it in just nine minutes." 

The not-so-good news, however, is that storm forecasts also rely heavily on data from NASA satellites that fly from pole to pole. Those satellites are nearing the end of their lifespan, and two replacement units—part of the JPSS program—aren't expected to launch until 2017 and 2023, thanks to funding shortfalls and mismanagement. According to the New York Times, that could leave a significant gap in coverage:

The United States is facing a year or more without crucial satellites that provide invaluable data for predicting storm tracks, a result of years of mismanagement, lack of financing and delays in launching replacements, according to several recent official reviews.

The looming gap in satellite coverage, which some experts view as almost certain within the next few years, could result in shaky forecasts about storms like Hurricane Sandy, which is expected to hit the East Coast early next week. 

It's not exactly clear how much worse hurricane forecasts would get during this coverage gap, though there is this to consider: "Experiments show that without this kind of satellite data, forecasters would have underestimated by half the huge blizzard that hit Washington in 2010."

At the same time, over at Capital Weather Gang, Steve Tracton has argued that looming budget cuts at the National Weather Service could slow further gains in storm predictions. (He has argued, in fact, that there's too much focus on satellites and not enough on many of the smaller programs within NWS that are equally crucial for weather analysis.) Our storm forecasts may be getting better, but that improvement isn't inevitable.



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Suzy Khimm · October 29, 2012

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