Researchers have found a distinct atmospheric pattern that could anticipate U.S. summer heat waves up to two weeks in advance.
The finding could allow scientists to warn the public of heat waves 15 to 20 days before the fact, which could help prevent instances of heat stroke and other temperature-related fatalities, a National Center for Atmospheric Research (NCAR) news release reported.
The research team looked at a 12,000-year simulation model that focused on weather in the Northern hemisphere. They noticed when a telltale "wavenumber-5" pattern emerged, a heat wave often occurred soon after.
"It may be useful to monitor the atmosphere, looking for this pattern, if we find that it precedes heat waves in a predictable way," NCAR scientist Haiyan Teng, the lead author, said. "This gives us a potential source to predict heat waves beyond the typical range of weather forecasts."
Wavenumber-5 is a "sequence of alternating high- and low-pressure systems (five of each) that form a ring circling the northern midlatitudes, several miles above the surface."
The pattern is also associated with "stagnant" or slow weather conditions, which have been linked to heat waves.
Heat waves are considered to be the "most deadly weather phenomena on Earth." In 2006 a heat wave was responsible for at least 600 fatalities. In 2003, a European heat wave killed over 50,000 people.
The researchers looked at weather records going back to 1948; they took note of instances when summer temperatures rose to 2.5 percent of weather readings for that time that spread across at least 10 percent of the country.
The team was only able to pinpoint 17 of these events throughout the past several decades, which was not enough to confirm their theory.
Looking at the virtual simulation the team was able to point to wavenumber-5 as a predictor of major heat waves.
When looking back to history, the team found certain past heat waves had been characterized by wavenumber-5-like patterns.
"There may be sources of predictability that we are not yet aware of," Teng said. "This brings us hope that the likelihood of extreme weather events that are damaging to society can be predicted further in advance."
