A developing El Nino pattern has caused forecasters at the Climate Prediction Center and National Hurricane Center to pull back a bit on the number of named storms forecast in the Atlantic basin this season.
El Nino is warming of the equatorial waters of the Pacific to much above normal conditions. It usually starts in the eastern Pacific as the NOAA animation above shows. The warming of the waters helps to generate thunderstorms which in turn transport heat into the upper atmosphere. This strengthens the jet stream over the Atlantic equatorial regions. Strong jet stream winds, or more precisely the shear they produce, tear apart developing tropical systems. It’s ironic that powerful storms like Katrina actually require benign conditions in which to first start developing!
A complete write-up on this topic from NOAA can be found here.
Ted Keller
Senior Meteorologist
KOLR/KSFX-TV
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