Hurricane Flossie, the Un-Forecastable

The islands of Hawaii are hardly immune to hurricane risks. In 1992, the powerful Category 4 Hurricane Iniki directly struck Kaua'i, causing almost $ 3 billion in damage. But there was something to note about 1992: It was an El Niño year, characterized by the spread of warm water from the western Pacific east towards the Americas. El Niños often have very busy central and eastern Pacific hurricane activity as a result of this extra ocean warmth -- and consequently, these years result in an increased hurricane risk to Hawaii. By these lights, Iniki at least made a kind of sense.

The same can't be said for Hurricane Flossie: This isn't an El Niño year. In fact, Flossie rapidly intensified late Friday and early Saturday over waters that weren't even all that warm, certainly not to the depth typically found when you get a powerful hurricane explosion of this kind. (For more discussion of Flossie's unexpected burst up to Category 4 see here and here.)

And after reaching Category 4 strength on Saturday -- with sustained winds upwards of 130 miles per hour--Flossie has now remained there for two full days, all the while getting closer and closer to the Hawaiian islands. Pretty much every six-hour forecast has predicted that Flossie should weaken ... and Flossie stubbornly refuses to comply. As of now, the official forecast from the Honolulu-based Central Pacific Hurricane Center, pictured below, takes Flossie south of the big island tomorrow evening, but a slight deviation in track could mean a big variation in damage potential. Meanwhile, the forecasts continue to suggest weakening, but I'm not at all sure whether to listen to them on this front any longer. The forecasting of hurricane intensity changes remains a key scientific weakness, and no storm has made this point more eloquently than Flossie.

As you can see, pretty much all of Hawaii is now within the so-called "cone of uncertainty," meaning Flossie's eye could travel directly over these areas if the storm changes its expected course. Moreover, parts of Hawaii could experience powerful hurricane winds and intense rainfall even if Flossie's eye stays offshore. Although a relatively small storm as hurricanes go, Flossie is far bigger than any of the islands, and may well brush them even if it doesn't make landfall.

But even though Flossie has started to seem more than a little scary, you still have to be impressed by this storm's incredible definition, including a perfectly clear eye: Flossie Infrared August 13.

In other news, the dilatory Atlantic hurricane season may be kicking into gear this week -- everyone is watching a tropical wave that pushed off the coast of Africa and that may soon be named a tropical depression. Check with hurricane guru Jeff Masters for more on this disturbance-with-potential. A strong tropical storm named Sepat has also spun up in the Pacific east of the Philippines and may be en route to Taiwan and China. Finally, the Fort Lauderdale Sun Sentinel ran an op-ed of mine on Sunday about the latest research suggesting that Atlantic hurricane numbers are dramatically increasing -- and the scientific fight this research has inevitably sparked. I conclude that although we don't know exactly which group of dueling experts is right on this front, perhaps we don't have to:

If some top scientists think hurricanes are getting worse, that's grounds for serious worry, period. So the reasonable response is to start investing now in better hurricane preparedness for our most vulnerable regions -- a move that makes good sense whatever global warming is doing -- while waiting for more definitive science to come in.

More soon on Flossie, and other storm punditry...