Hurricane season officially begins June 1 — though global warming will ultimately move that date up just as it is moving up the spring snowmelt. Indeed, some evidence suggests the hurricane season has been getting longer for decades (see here and below).
As Jeff Master, our favorite meteorologist and hurricane blogger, noted in November, “This year is now the only hurricane season on record in the Atlantic that has featured major hurricanes in five separate months” (see “A new record for the hurricane season of 2008“). Saturday, Masters explained that had “the large extratropical storm (90L) that has been pounding Florida” this week “spent another six hours over water, it very likely would have been declared a tropical/subtropical depression/storm” — that is, it would have been “the season’s first named storm.” So I won’t wait until June 1 to revise and update some posts from last year on why global warming will lead to much worse killer storms.
Hurricanes can get much, much bigger and stronger than we have so far seen in the Atlantic. The most intense Pacific storm on record was Super Typhoon Tip in 1979, which reached maximum sustained winds of 190 mph near the center. On its wide rim, gale-force winds (39 mph) extended over a diameter of an astonishing 1350 miles. It would have covered nearly half the continental United States.
“More than half the total hurricane damage in the U.S. (normalized for inflation and populations trends) was caused by just five events,” explained MIT hurricane expert Kerry Emanuel in an email. Storms that are Category 4 and 5 at landfall (or just before) are what destroy major cities like New Orleans and Galveston with devastating winds, rains, and storm surges.
In Part 2, we’ll look a little more in detail at Katrina and Gustav, and why they weren’t as strong and hence as devastating at landfall as they could have been. But let’s first ask — How did Katrina turn into a powerful Category 5 hurricane?