With hurricane season over — it officially ends today — it looks like Florida has skated again this year. The season produced nine named storms, three of which became hurricanes, but none that made landfall as hurricanes in the United States. Chris Landsea, science and operations officer at the National Hurricane Center in Miami, offers his assessment of the season.
Why such a quiet year?
I think the main reason is the El Niño that developed in the Pacific Ocean this year. We get an El Niño every four to six years and it … changes the global weather pattern. Some of them are nice, and some of them aren't so nice. The one beneficial aspect is the reduction in Atlantic hurricanes. You tend to get more windshear that disrupts the storms. … We've seen promising looking tropical waves but they would sputter or either not develop or barely develop at all.
How long is this El Niño expected to last?
It's not very predictable. … Most last just a year. The question is whether it will stick around for the 2010 hurricane season. Most El Niños last for a year, but we have seen others span two hurricane seasons. It's usually the ones that start a little late that get very strong. It remains to be seen if this El Niño causes two quiet seasons in a row.
Quiet, of course, can depend on where you live. Do you think our perception of a season focuses too much on hurricanes' impact on the U.S.?
Yes. You could have a very busy year like last year, but the folks in Florida were very fortunate because we did not have any direct impacts. If it's an active year, your chances of getting hit do go up. If you speak of a specific county or city, your chances of getting hit are very small. But if it's a quiet year, and that one hurricane hits your city or county — like Miami during the 1992 Hurricane Andrew — then it was the worst hurricane season you've experienced in your life.
What's a better measure of a season?
Just counting the number of storms can be very misleading.
We use something called "accumulated cyclone energy" (a measurement of the total activity of each storm, and the seasonal total of all storms).
Is this why the hurricane center's seasonal predictions now offer a possible range of storms instead of a specific number?
We're never going to get it exactly right. To provide that kind of precision is a little misleading, at least in our opinion. We express it two ways: One is a range, so this year we said there were 4 to 6 storms expected. We also give the chances of a quiet, average or busy year.
For this year, there was a 40 percent chance of a quiet, 50 percent chance of near average, and 10 percent chance of a busy year.
So much has been made in recent years about global warming's impact on hurricanes. How does that figure in with this fluctuation in storms?
Just like there were some who were misguided in saying the 2005 season (27 named storms) was a harbinger of global warming, there were folks on the other side who said the 2006 and 2007 season meant there was no indication of global warming. …
In general, Atlantic hurricane activity has been very busy since the mid '90s. … That's not to say I don't think there's any global warming influence. I do think hurricanes are being impacted by global warming, but it's a really tiny, tiny component. …
Even with a Category 5 hurricane with 175 mph winds, maybe 1 to 2 mph could be ascribed to global warming. But if that's the case, it's so small we can't measure it.
Andy Boyle can be reached at firstname.lastname@example.org or (727) 893-8087.