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Hurricane Intensity
Mon Jul 21, 2003
Listen in RealAudio 
Hi, I'm Bryan Yeaton for the Weather Notebook. It used to be a tropical storm could spin up
gale-force winds before anybody knew it was there. The September, 1900, Galveston Hurricane
might be considered as one example of that. In the 1960'satellites came along and allowed us
to track each hurricane from its birth.
But something in the way hurricanes moved still bothered forecasters. It seemed erratic: a
straight line, a curve, a zig-zag, even a complete loop. These motions weren't forecast very
well until computers got better at tracking the high-altitude steering winds. Now we're able
to forecast landfall to within 30 miles on average, a full day ahead. But there's one part of
a hurricane that keeps scientists chewing on their pencils: predicting its intensity.
Even the best forecasters have trouble predicting when or how much a hurricane will strengthen
or weaken. The biggest stumbling block for forecasters seems to be the hurricane's eyewall.
That's the zone right around the calm center of the storm, but where the winds are fiercest.
It's also the hardest place to put instruments. Winds in the eyewall interact with the ocean
surface in ways we don't fully understand. One thing we do know: hurricanes need warm water
to live. So scientists are looking at new ways to measure the depth of warm water. Since
water expands as it warms up, one technique is to use remote instruments to measure the height
of the sea surface. This could help tell us how much warm water lies beneath, ready to fuel
the next hurricane that rolls by.
Thanks today to contributing writer Bob Henson. The Weather Notebook is underwritten by Subaru
of America, with funding provided by the National Science Foundation. Thanks to Marketing
Manager Melody Nester.
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