A Cirrus Sign of Tornadoes – An Early Clue of Destructive Weather

Brightness Temperature US June 2021 Annotated

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June 16, 2021.

Cirrus Injection Illinois

June 16, 2021. Detail.

Severe thunderstorms can draw plumes of cirrus clouds into the stratosphere, an indication that twisters, big hail, or harmful winds might be coming quickly.

After a group of twisters emerged from a squall line on June 20, 2021, and one touched down in the Chicago residential area of Naperville, the results on the ground were apparent. The EF-3 twister had 140-mile-per-hour (225 kph) winds that fell countless trees, hurt 11 individuals, and cut electrical power to 10s of thousands. The twister harmed a minimum of 230 homes, consisting of one that collapsed.

From a satellite point of view, the characteristics of the storm system were more subtle, however they used a minimum of one early idea that the squall line had a likelihood of discharging harmful weather condition. The cloud temperature level information above, from the Advanced Baseline Imager (ABI) on the GOES-R satellite, was gathered about 45 minutes prior to the twister touched down. Warmer air is red and cooler air is blue.

“Notice the plumes of warm air downwind of updrafts—the cold overshooting cloud tops,” stated Kristopher Bedka of NASA’s Langley Research Center. “Those are what we call ‘above-anvil cirrus plumes’ (AACPs)—cirrus clouds that were injected into the stratosphere.”

Most thunderstorms can mature to the tropopause, the limit in between the troposphere and the stratosphere. When strong storms reach the tropopause, their tops flatten out, providing an anvil-like look. Above-anvil cirrus plumes type when particularly extreme updrafts pierce the tropopause and air flow draws cirrus cloud tops into the stratosphere. Cirrus plumes are generally warmer than underlying anvil clouds since the air in the stratosphere increases with elevation.

“Detecting an AACP isn’t a guarantee that you’ll get a tornado or other severe weather like we saw with the Naperville event, but our analysis of more than 400 of these events observed by either GOES-14 or GOES-16 showed about three-quarters of the time these cirrus plumes appeared 10 minutes or more before the most severe weather hits,” stated Bedka. “Cirrus plumes routinely occur atop the world’s most intense storms, and tracking them can provide valuable lead time that saves lives and property.”

NASA Earth Observatory images by Joshua Stevens, utilizing GOES 16 images thanks to NOAA and the National Environmental Satellite, Data, and Information Service (NESDIS).