La Niña intensifies threat of hurricane season
This image from NASA shows La Niña as a large blue swell
in the Pacific Ocean
|Science Correspondent Ann Kellan reports on what the comeback of La Nina means for hurricane season
September 10, 1999
Web posted at: 10:28 p.m. EDT (0228 GMT)
By Science Correspondent Ann Kellan
(CNN) -- This hurricane season has been normal so
far, with two hurricanes hitting land. But forecasters say
brace yourself -- the second half of the season could be a
replay of last year -- with devastating storms like Bonnie
Scientists say La Niña is to blame. That's the weather
phenomenon characterized by cooler than normal waters in
parts of the Pacific.
Early this spring, it looked like La Niña was fading. NASA's
Tony Busalacchi says now it's making a comeback, with cooler
Pacific waters stretching as much as 6,000 miles.
"There's still a reservoir of cold water at depth in the
ocean, and when the winds in the equatorial Pacific
strengthen as they normally do on seasonable time scales, it
brought cold water up to the surface like we saw in the
past month," Busalacchi said.
Affects jet stream
La Niña, like its counterpart El Niño, dramatically affects
the jet stream -- the high winds that guide weather patterns
in the United States.
When Pacific waters were warmer with El Niño, the sub-
tropical jet stream shifted south, which worked to block and
weaken hurricanes headed toward the Eastern United States.
La Nina, on the other hand, leaves the door open for the
"Jet stream recedes, unfortunately it allows these hurricanes
to spin up and quite often make landfall in the Eastern
Seaboard of the United States," Busalacchi said.
There were seven hurricanes that hit landfall during the 1998
hurricane season. This year, so far, there have been two.
Like last year, the second half of the season was when the
most powerful storms hit shore.
So it's not over yet. Scientists say it could last another
one to three months, taking us through the fall, which is the
last half of hurricane season, and maybe early winter.
As hurricane season peaks, forecasters warily eye Floyd
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National Weather Service Home Page -U.S. Government warnings & forecasts
NOAA La Niña page
La Niña Summit
NOAA/PMEL/TAO El Niño & La Niña Predictions and Forecasts
TAO Temperature and Dynamic Height Animation
Meteorology Guide: the online guides
TROPICAL PREDICTION CENTER/NATIONAL HURRICANE CENTER
Hurricane and Storm Tracking
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