New technology can predict severe storms 45 minutes earlier than radars

June 18th, 2009 - 11:57 am ICT by ANI  

Washington, June 18 (ANI): A team of scientists has developed a way to measure temperature changes in the tops of clouds to improve forecast times for rapidly growing storms, by predicting severe thunderstorms up to 45 minutes earlier than relying on traditional radar alone.

The method was developed by scientists from the Cooperative Institute for Meteorological Satellite Studies (CIMSS), US.

“The value of detecting and analyzing these changes is that we can get up to a 45-minute jump on radar detection of the same storm system. A ‘nowcast’ becomes a ‘forecast’,” said CIMSS scientist Wayne Feltz.

Clouds start cooling long before radar can identify them as storms. As a warm cumulus cloud grows and expands upward into higher altitudes, it will rapidly cool.

Rapid cloud-top cooling indicates that a cloud top is rising into the frigid upper reaches of the atmosphere and can reveal the formation of a severe storm.

Cloud temperatures can be measured by the wavelengths of light they radiate in the near-infrared and infrared frequencies.

Current geostationary satellites, which stay over the same location on Earth, can discern five different bands in these frequencies, each band revealing a different state of cloud development.

Looking down from space, the satellite can determine whether the cloud top consists of liquid water, supercooled water or even ice.

By running high-speed five-minute satellite scans through a carefully designed computer algorithm, the scientists can quickly analyze cloud top temperature changes to look for signs of storm formation.

“We are looking for transitions,” said Feltz. “Does the cloud top consist of liquid water that is cooling rapidly? That could signal a possible convective initiation,” he added. (ANI)

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