Artificially triggered convection

Dan Robinson

I'm looking for documented examples of artificially triggered convection (aside from forest fire pyrocumulus) from power plants and industrial sites. Specifically I'd like to know of NWS statements, warnings, discussions, surveys or case studies relating to these events. I'd also be interested to see photographs that chasers may have of large Tcu or Cb clearly triggered by the exhaust of an industrial or power plant site.

Man-Made Snow in Green Bay - January 15, 1999

Weather conditions were just right on the morning of January 15 for snow flurries to fall from clouds which developed from the steam emmitted by factories and paper mills in Green Bay. As the steam from the smoke stacks rapidly rose into the frigid air, the moisture condensed, producing clouds. What made this morning unusual was the presence of a strong inversion, or warm layer aloft, which helps trap the moisture. The moisture then had a chance to coalesce and produce snowflakes. Up to an inch of snow fell in the Green Bay suburb of Allouez, downwind of the mills.

The Green Bay National Weather Service Doppler radar is so sensitive that it actually detected the light snow across the area, even though skies were clear elsewhere in northeast Wisconsin.

This picture is taken from the west side of Green Bay, looking toward the paper mills.

this picture is a 1.5 degree elevation reflectivity image. Note how the precipitation is moving away from the mills, as light southwest winds blow the moisture over the bay.
When I first joined this site back in March 2004, someone had posted photos of a power plant-assisted thunderstorm. Though the plant was not the original cause, the steam was flowing into the storm's inflow, sustaining the pulse cell for longer than average lifespan. I think that's how I remembered it.
Here is a very good example, including photos of the pretty storm that formed as well as a radar loop:

The trigger, in this case, was oil refineries in Wood River, IL. The Web site describes the process that occurred - no question the refineries played a major role, though the conditions had to be just right for this to occur.