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November 24, 2015

PECAN seeks to better understand nighttime thunderstorms (Image 2)

A cloud-to-ground lightning strike during a nighttime thunderstorm in the Midwest. In summer 2015, researchers fanned out across the Midwest as part of the Plains Elevated Convection at Night project to study nighttime thunderstorms like this one.

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In summer 2015, atmospheric scientists participating in the Plains Elevated Convection at Night project -- or PECAN, fanned out across the Great Plains in an effort to better understand the atmospheric conditions that lead to storm formation and evolution after sunset. Results gleaned from this research may ultimately help improve forecasts of these sometimes damaging storms. The project, which is largely funded by the National Science Foundation (NSF), involved scientists, students and support staff from eight research labs and 14 universities.

Daytime thunderstorms are more easily understood than those that occur at night. In the day, the sun heats the surface of Earth, which in turn warms the air directly above the ground. When that warm air is forced to rise, it causes convection -- a circulation of warm updrafts and cool downdrafts -- and sometimes creates a storm.

"At night, the entire storm circulation is elevated higher off the ground," said National Center for Atmospheric Research scientist Tammy Weckwerth, a PECAN principal investigator. "This makes observations of the conditions leading to nighttime thunderstorms much more challenging because that part of the atmosphere is not well covered by the network of instruments we normally rely on."

To help tackle this problem, PECAN researchers used lab-equipped aircraft, ground-based instruments and weather balloons to collect data higher in the atmosphere. The data will help scientists characterize the conditions that lead to individual storm formation, as well as to the clustering and organizing of these storms into large-scale systems, which can result in significant precipitation.

The researchers say the PECAN project will provide researchers and operational forecasters with valuable insights into thunderstorms at night and improve the ability to model them more accurately. [Research supported by NSF grant AGS 12-37404, "The Mechanisms for the Maintenance of Nocturnal Convective Systems."]

To learn more about PECAN, see the NSF Discovery story 10 things to know about thunderstorms that strike at night; or see NSF press release 15-057, Scientists tackle mystery of thunderstorms that strike at night. (Date image taken: summer 2015; date originally posted to NSF Multimedia Gallery: Nov. 24, 2015.) [Image 2 of 5 related images. See Image 3.]

Credit: Jacob DeFlitch, Meteorologist

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