Spring is just around the corner and chances are you have seen no snow in Austin this winter. That is unless you live in a narrow stretch of East Austin between Decker Lake and the Austin Airport.
It did snow there, and pretty much only there, one Monday morning in mid-January. The source of that snow was most likely the Decker Creek Power Plant, according to the National Weather Service office in New Braunfels. It appears that Austin Energy's Sand Hill Energy Center may have also been responsible for snow in Del Valle.
Initially, people thought the light snow that covered East Austin in a narrow swath from Lake Walter E. Long to the Austin airport on Monday was caused by “lake effect” snowfall. That phenomenon creates highly localized snow cover when evaporation from lakes hits frigid air that gets blown overland.
But lake effect snow rarely happens over lakes as small as Walter E. Long. And no other nearby (and larger) lakes seemed to generate any snow.
These facts prompted NWS Meteorologist Keith White to undertake a little “forensic meteorology.”
“I’m a curious person, so I figured I’d like to be able to explain as best as possible what happened,” he said. “It’s just part of science, and I’ve always been a scientist.”
White compared wind and temperature data with on-the-ground reports of snowfall (including some pictures posted by yours truly) to conclude the snow was caused by what is called “industrially enhanced snowfall” or “factory effect snow.”
“In a process pretty similar to how lake effect snow works, industrial stacks that release steam into the atmosphere [create] small snowflakes,” White said. “And those blew in pretty strong north winds … and created light snow accumulations there near the Austin airport and Farm to Market 973 as well.”
Satellite images of snow remaining a couple of days later reveal just how narrow a band of snow was spread, turning to freezing precipitation just north of the airport.
White said he’s received pictures of snowfall in Del Valle that suggest a similar phenomenon took place around the Sand Hills Power Plant.
Factory effect snow is not uncommon in certain parts of the country, but White has found no records of it happening in Austin in recent history.
Austin Energy questions the source of snow
Jack Borsch, Austin Energy’s interim vice president of power production, told KUT he does not believe that the Decker Creek Power Plant could produce enough water vapor to be responsible for the snow.
The Decker plant does use some water for cooling and other operations, but, since the plant retired two older steam turbines, it has not released steam from its cooling tower, Borsch said.
The power plant now operates four natural gas-powered generating turbines. Borsch said those release about as much heat and vapor as two Boeing 737 airplanes.
“If you think the Southwest [Airline] jets would produce that much snow, that’s just not realistic to me,” Borsch said.
The Sand Hill Energy Center, located in the same area where snow was also reported, does have a cooling tower. Though, again, Borsch does not believe the amount of vapor it releases could be responsible for the snow.
“I'm not claiming to be an expert in meteorology, but I am an expert in gas turbines," he said. “I’ve been in this business a long time, and this is quite honestly the first and only time I’ve ever heard of this effect."
Borsch thinks lake effect snow is a more likely explanation.
Decker Lake was initially built to cool the power plant in 1967. For years, anglers reported warmer-than-usual water in some parts of the lake, something that could add to lake effect snow. But Austin Energy says since they shut down their older generating units at that location, the water is not significantly warmed by the power plant.
Experts weigh in
Other weather and geoscience experts told KUT that White’s analysis, that the plants caused the snow, appears sound.
“This is something that happens all over the country,” said Matt Lanza, a meteorologist with Space City Weather.
Lanza and others say that vapor from steam stacks is not necessary to create the human-made snow. In certain conditions, the most important factor is a heat source.
“It just has to be a heat source, that’s all that matters,” Lanza said. “You don’t necessarily need to have it to allow for a situation to produce precipitation.”
Sasha Carter, a geophysicist who teaches earth science at San Diego Miramar College, said heat can create an updraft, carrying already humid air up higher and, in the process, produce precipitation.
“Moisture that’s already present in the air is also being wringed out of the air,” he told KUT. “You’re essentially cloud seeding.”
Jet engines have also been known to produce snow under the right conditions. In fact, that’s how snow machines were invented.
According to the Guinness Book of World Records, in the 1940s, Canadian researchers accidentally made snow by blasting water-saturated air through a jet engine. While the researchers took no commercial interest in the discovery, others did and the first generation of snow machines was born.
When asked in an email about potential health or environmental concerns related to industrially-enhanced snow, representatives from Austin Energy said “the water vapor released from cooling towers is clean water.”
