Meteorologists may have found a way to predict some killer heat waves up to two or three weeks in advance. Now, the best they can do is about 10 days.
Heat waves are the deadliest weather threat in the United States, killing more people each year than hurricanes, tornadoes, floods and earthquakes combined.
An earlier warning would help cities prepare for the heat wave, arrange to open up cooling centers and check on the elderly, said Gerald Mehl, co-author of a study that describes the forecasting clue.
Now, research lead by Haiyan Teng of the National Center for Atmospheric Research (NCAR) has identified an atmospheric wave pattern that precedes North American heat waves by two weeks. The study, published in the journal Nature Geoscience, has the potential to improve forecast of such extreme events.
A distinctive atmospheric wave pattern over the Northern Hemisphere may help predict summertime U.S. heat waves more than two weeks in advance, scientists say.
“People haven’t connected this particular wave pattern to the heat waves before,” Teng said, but “many [heat waves] tend to be led by this wavenumber-5 pattern.”
The wavenumber-5 pattern, a sequence of alternating high and low pressure systems (five of each) that for a ring circling the northern mid-latitudes, can lend itself to slow-moving weather features and raise the chances of stagnant conditions often associated with prolonged heat spells, the researchers said.
The researchers looked only at heat waves over the United States, although the research could also be extended to Europe and Asia. ‘We think this pattern can provide a useful pattern fro heat waves in other countries,” Teng said.
This wave pattern was seen before the 1980 heat wave that was blamed for 1,250 deaths and pushed temperatures over 100 degrees in Dallas every day, said Randall Dole, a senior scientist at the National Oceanic and Atmospheric Administration (NOAA). Triple-digit temperatures in Dallas persisted for a record 42 consecutive days that year. Dole, who wasn’t part of the study, said the science behind the study is sound, significant and may be practical after extensive testing.
“The scientific value is whenever we break through what is supposed to be a predictability barrier, that tells us what we need to have in models. And it begins to provide the forecasters with something that they begin to monitor two to three weeks out,” Dole said.
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