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"Sear Seer" -- The Discovery Files

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Scientists at the National Center for Atmospheric Research have fingerprinted a distinctive atmospheric wave pattern that can foreshadow the emergence of summertime heat waves in the United States more than two weeks in advance.

Credit: NSF/Karson Productions

Audio Transcript:

(Sound effect: Atmospheric sounds) Packin' heat

I'm Bob Karson with the discovery files--new advances in science and engineering from the National Science Foundation.

Scientists at NCAR, the National Center for Atmospheric Research, have identified a distinctive atmospheric wave pattern that can foreshadow extreme summer heat waves, 15--even 20--days in advance; far better than we can do today.

The researchers looked at weather records going back to 1948, but only 17 events met their criteria. Needing a larger sample, they turned to an NCAR atmospheric simulation model of the earth that spanned some 12,000 years. That gave them nearly 6,000 heat waves to study. The scientists noted that heat waves in the northern hemisphere were apt to be preceded by what is called the 'wavenumber-5 pattern.'

It is this pattern--a sequence of alternating high and low pressure systems--five of each--that can help predict future heat waves. The simulation model showed the pattern tends to move westward against the jet stream in the 20 days leading up to a heat wave. Eventually a high pressure ridge from the north Atlantic settles over the U.S. shutting down rainfall and setting the stage for a heat wave to emerge.

Looking for this pattern could give us extra time to prepare. And the researchers are looking for patterns that might foreshadow other weather phenomena.

"The discovery files" covers projects funded by the government's National Science Foundation. Federally sponsored research--brought to you, by you! Learn more at or on our podcast.

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