Wi-Fi threatens weather forecasts

Wireless technology dangerously clutters the airwaves that meteorologists rely on to monitor thunderstorms, hurricanes and tornadoes, blacking out large swaths of weather radar maps.

Wi-Fi, remote surveillance cameras and other wireless tech emit radio waves that can disrupt those from weather radars. This interference, which creates blind spots on radar images, is a growing problem, meteorologists report October 14 in the Bulletin of the American Meteorological Society.

“Interference could hide an approaching tornado or a strong convective system and we wouldn’t have any warning,” says coauthor Elena Saltikoff, a meteorologist at the Finnish Meteorological Institute in Helsinki.

Weather radar dishes blast radio waves that ricochet off water droplets in the air. Measuring these echoes allows meteorologists to monitor weather conditions up to hundreds of kilometers away. The returning radio waves can be less than a quintillionth the strength of the original signal, though, making the system vulnerable to devices that emit radio waves on similar frequencies. This disruption looks like blotches and streaks on radar images. While software can remove interference, it often can’t salvage the underlying weather data.

Interference has been a meteorological nuisance for decades, but the problem has grown stratospherically, says study coauthor John Cho, an atmospheric radar scientist at the MIT Lincoln Laboratory in Lexington, Mass. In Europe, reports of wireless devices interfering with weather radars went from zero before 2006 to more than 200 in 2012. These incidents largely involved equipment such as Wi-Fi routers that had been hacked to circumvent built-in safeguards meant to reduce interference.

In South Africa, interference became so bad that meteorologists switched radar frequencies, a move that cost millions of dollars in new equipment. Even after the switch, operators say they still battle rising interference.

“We have to protect these frequencies; otherwise, forecasts and observations of storms will suffer,” says Robert Palmer, a radar meteorologist at the University of Oklahoma’s Advanced Radar Research Center in Norman.