Making hazardous weather forecasts more accurate

A lightning strikes over the sky in Wuhan City, central China’s Hubei Province,( File Photo Xinhua/Zhou Guoqiang) (mt)

New York – To identify precisely where severe winds, hail or tornadoes are more likely to occur within storm clouds, NASA scientists have developed a new hazardous thunderstorm forecast method by combining satellite images with novel algorithms.

“We are able to analyse the locations where severe storms most frequently occur and when they occur with unprecedented detail using commonly available satellite imagery,” Kristopher Bedka, physical scientist at NASA’s Langley Research Center in Hampton, Virginia, said in an official statement on Tuesday.

Forecasts play key roles in many people’s lives, from planning picnics at the park, to cancelling flights and avoiding weather-related tragedies. Because weather can be a life-or-death matter, researchers work hard to develop new technology and ways to provide earlier and more accurate forecasts.

Thunderstorms form when warm, moist air rises rapidly into the atmosphere. These air currents produce cloud formations known as cumulonimbus incus, or anvil clouds, which look similar to an atomic bomb explosion with a flat and wide top.

Forecasters have known for years that anvil clouds indicate thunderstorms. But anvil tops can be miles wide, and it is sometimes difficult to distinguish where within those clouds hazardous weather may be occurring.

Bedka said it is crucial to figure out what is a hazardous storm and what isn’t within anvil clouds, especially because strong updrafts pose serious risks for things like flying aircraft.

To really target the action, Bedka focuses on updrafts that are strong enough to punch into the stratosphere. That penetration creates lumpy clouds, which look almost like the top of a cauliflower sticking out from an anvil top.

Known as overshooting tops, these lumps indicate areas where strong thunderstorms ? sometimes hail and tornadoes ? usually occur.

Although researchers know that overshooting tops indicate thunderstorms, Bedka said it is sometimes difficult to spot them quickly enough to provide warnings for severe weather.

To deliver almost instant forecasts, the researchers combine their satellite observations with powerful software engineering.

“We can process an image that covers the entire United States in less than two minutes,” Bedka said.

Overshooting tops research could make a difference for thousands of people worldwide under various situations, Bedka said.

“In the US we are fortunate in that we can track hazardous storms using weather radar data,” he said.

“But many regions in the world do not have these radars, so satellite imagery and hazardous storm detection products like mine are often the only data that forecasters can use to warn the public,” Bedka noted.