All throughout the summer, eerie storm plumes that look strikingly like smoke have stretched over the United States. This peculiar weather phenomenon is known as the Above Anvil Cirrus Plume (AACP) and usually spells trouble.
Produced by intense updrafts that pierce through the boundary between the lowest part of Earth’s atmosphere, called the troposphere, and the stratosphere, AACPs create jet-stream winds that give rise to U- or V-shaped areas of cold temperatures, as seen in the satellite image above.
According to NASA, this type of storm plume “looks like a plume of smoke emanating out from the top of what, in all likelihood, is a serious storm” and “is a strong indicator that a storm may produce a tornado, large hail, or powerful wind.”
Spotted from space by NASA satellites on multiple occasions, the plumed storms were seen on June 29 over North Dakota, where they ended up producing hail the size of a baseball, reveals a new photo released by the space agency. A month before, satellites picked up AACP over northeast Kansas and southern Nebraska, where they unleashed numerous tornadoes, baseball-sized hail, and 80 mph straight-line winds.
This fierce-looking storm plume is currently being studied by a team of researchers led by Kris Bedka, an atmospheric scientist at NASA’s Langley Research Center in Hampton. And, as Bedka points out, “these are the storms you really, really need to look out for.”
Storms are a-brewin! A distinctive, identifiable cloud formation in satellite imagery often signals damaging storms below. Looking like a plume of smoke out of a chimney, it actually shows the top of a serious storm. See what we know about these storms: https://t.co/7EPV9AVbHy pic.twitter.com/ilW4jBSQ2R— NASA (@NASA) August 16, 2018
Writing in a paper published this month in the Weather and Forecasting journal of the American Meteorological Society, Bedka’s team describes the AACP phenomenon as seen in visible and infrared satellite imagery and details 405 occurrences, along with their most distinctive features.
The images were recorded at one-minute intervals by the Geostationary Operational Environmental Satellite (GOES) Network of the National Oceanic and Atmospheric Administration (NOAA) — in particular GOES-14 and GOES-16.
“We found about 400 plume-producing storms across 13 severe weather outbreaks,” said Bedka, “and in about 100 of them you had a plume appearing 10 minutes before the first warning, potentially providing additional lead time for saving lives and property.”
Storm in east-central Colorado on 29 July produced 83 mph wind gust and baseball size hail. Large overshooting top and above anvil cirrus plume obvious with this storm in GOES-16 1-min VIS and IR. Sandwich combo here. #cowx Full res: https://t.co/NoRJs5Q8W1 pic.twitter.com/4rL7R67JLb— Bill Line (@bill_line) July 30, 2018
Although this type of storm plume has been studied for more than 35 years, the AACP phenomenon had largely remained a mystery. Not much was known about why some storms generate this kind of cirrus plumes, while they’re completely absent from other nearby storms. At the same time, the team was interested in finding out “exactly how severe are storms with AACPs, and how AACP identification can assist with severe weather warning,” the authors wrote in their paper.
As it turned out, these plumes are a precursor of large hail in most of the cases, as well as high winds and major tornadoes. In fact, AACPs have been associated with 73 percent of severe weather reports. At the same time, AACP storms have been linked to 14 times more severe weather events per storm than storms without plumes, the researchers discovered.
“In addition, 88 percent of EF-2 or greater tornadoes and 86 percent of 2-inch-plus hail reports came from plume-producing storms,” NASA officials state in the news release.
Nice above-anvil cirrus plume (AACP) associated with the severe thunderstorm (producing large hail to 2.75" and damaging winds to 70 mph) moving across Nebraska https://t.co/dBvAQB710n @NWSNorthPlatte @krisbedka #NEwx pic.twitter.com/mrYVwpsNoO— Scott Bachmeier (@CIMSS_Satellite) August 16, 2018
However, the study uncovered that AACPs do make themselves present, on average, 31 minutes before a major storm hits. This means that their presence can tip off weather forecasters that severe weather is fast approaching and help them provide earlier warnings.
This makes these smoke-looking plumes “extremely helpful for protecting lives and property,” not only in the U.S. but also worldwide, the team concluded.
Weather forecasts aside, when AACPs are brewing, their presence has a certain impact on climate too, NASA points out.
As study co-author Elisa Murillo of the University of Oklahoma’s School of Meteorology explains, plume signatures “represent transport of ice and water vapor into the stratosphere,” the latter being a powerful greenhouse gas which can produce “strong impacts on climate.”