Since Hurricane Katrina came so soon after the four dramatic
hurricanes of 2004 (Charley, Frances, Ivan and Jeanne) and the
strange weather of last winter (including record-setting rainfall
in Los Angeles), it is little wonder that people are concerned that
something is amiss. The weather is becoming more extreme, more
capricious ““ and more deadly. Indeed, Life Magazine
proclaimed “The Year of Killer Weather” on its cover,
asking “Why Has Nature Gone Mad?”
It was published a dozen years ago, but it could be reprinted
annually, before and since that time. Every year is the year of
“killer weather” somewhere, and not a day goes by that
someone doesn’t have reason to question nature’s
sanity.
Was global warming complicit in the existence, intensity and/or
trajectory of Hurricane Katrina? Maybe, but at present any linkage
is speculative.
There is a strong relationship between Atlantic hurricane
activity and a 40- to 50-year oscillation in important
environmental conditions, including tropical Atlantic sea surface
temperatures. We’ve been in the active phase of this cycle
since the mid-1990s.
The present favorable conditions should remain with us for some
years to come. Additionally, being in an active phase doesn’t
mean the United States will necessarily be hit.
Quite a number of tropical cyclones that develop in the Atlantic
never make landfall; they pass into the central Atlantic to die or
weaken into extra-tropical weather systems. The last two years have
simply been the statistics catching up with us.
We’re halfway through the decade of the 2000s with five
major hurricane landfalls (Category 3 and above) in the U.S. to
date. There’s no assurance we’ll surpass the 1940s,
when 10 such storms hit the mainland.
Hurricanes have often come in clusters, independent of the
Atlantic oscillation phase. The next two decades saw only two major
hurricane landfalls in Florida in total, and there were none in the
1970s and 1980s. Even in the 1990s there was only one major Florida
strike, Hurricane Andrew.
Where were the hurricanes making landfall instead? In the 1960s
and 1970s, they were striking farther west along the Gulf Coast. In
the 1950s and 1980s, 10 major hurricanes passed over or very close
to the Carolinas.
We bear the burden of short memories. I know a family that moved
from Southern California to Florida in part because of our
earthquake threat. The extended lull in Florida hurricane activity
led them to believe that “hurricanes don’t hit Florida
anymore.” They moved very close to the town of Stuart, and
hurricanes Frances and Jeanne passed right over their house. How
soon we forget.
It may surprise you to learn that Southern California is not
completely immune. On Sept. 25, 1939, an unnamed tropical storm
made landfall between Los Angeles and San Diego, packing 65 mph
winds, killing 45 people and causing $27 million in damage,
adjusted for inflation.
Just another year of “killer weather.”
Fovell is an atmospheric and oceanic sciences
professor.