Friday, 25 November 2016 18:26

Lightning strikes can improve storm forecasts: study

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Data gathered from lightning strikes can help precisely forecast storms, a new study has found. The study presents a new way to transform lightning strikes into weather-relevant information. The US National Weather Service has begun to use lightning in its most sophisticated forecasts, researchers said.

This method, however, is more general and could be used in a wide variety of forecasting systems, anywhere in the world, they said. "When you see lots of lightning you know where the convection, or heat-driven upward motion, is the strongest, and that is where the storm is the most intense," said Robert Holzworth, professor at University of Washington in the US.

"Almost all lightning occurs in clouds that have ice, and where there's a strong updraft," said Holzworth. Researchers tested their method on two cases: the summer 2012 derecho thunderstorm system that swept across the US and a 2013 tornado that killed several people in the Midwest.

"Using lightning data to modify the air moisture was enough to dramatically improve the short-term forecast for a strong rain, wind and storm event," said Ken Dixon, a former UW graduate student who now works for The Weather Company.

The simple method might also improve medium-range forecasts, for more than a few days out, in parts of the world that have little or no ground-level observations. The study used data from the UW-based WorldWide Lightning Location Network, which has a global record of lightning strikes going back to 2004.

Researchers use lightning to improve forecasts for convective storms, the big storms that produce thunderstorms and tornadoes. Apart from ground stations, weather forecasts are heavily dependent on weather satellites for information to start or "initialise" the numerical weather prediction models that are the foundation of modern weather prediction.

What is missing is accurate, real-time information about air moisture content, temperature and wind speed in places where there are no ground stations. "We have less skill for thunderstorms than for almost any other meteorological phenomenon. The results show that lightning data has potential to improve high-resolution forecasts of thunderstorms and convection," said Cliff Mass, professor at UW.

The new method could be helpful in forecasting storms over the ocean, where no ground instruments exist. Better knowledge of lightning-heavy tropical ocean storms could also improve weather forecasts far from the equator, Mass said, since many global weather systems originate in the tropics. The study was published in the Journal of Atmospheric and Oceanic Technology.

Courtesy – Deccan Herald

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