Like a giant smokestack, percolating Mount St. Helens let loose a billowing steam plume easily seen Tuesday in downtown Portland, Ore., about 50 miles away.
Cold weather combined with the volcano’s ongoing release of water vapor to make the display particularly impressive, scientists said. Mount St. Helens has been undergoing a low-key eruption since September 2004.
“You look at your industrial stacks around town and they’re putting out nice vapor plumes today, as well,” said volcanologist Willie Scott at the Cascades Volcano Observatory in Vancouver, about 160 miles south of Seattle and 50 miles from the mountain.
The white plume emitting from the snowy peak could be seen clearly against a blue sky.
The vapor temperature was near the boiling point of water — 212 degrees — while temperatures at the mountain were around or below freezing, Scott said.
“The water vapor’s condensing rapidly, and it’s making a very attractive plume,” said seismologist Bill Steele at a University of Washington lab that has been monitoring the peak with the observatory.
Vapor has been rising from the volcano since before it rumbled back to life more than two years ago, extruding lava into the crater created when the mountaintop blew off in May 1980, flattening forests for miles and killing 57 people.