Mount St. Helens shot out a gaseous eruption for the third time in less than 24 hours yesterday while emitting ominous signals indicating that lava and gas were churning below the volcano's jagged crater.

The latest eruption at 5:20 p.m. PST was described as a "small gas emission" that sent up a cloud of steam with a small amount of ash to an elevation of about 23,000 feet, about 13,000 feet above the crater.

"The plume is drifting toward the northwest," said Larry Voshall of the state Department of Emergency Services.

"A flash-flood watch continues in effect near the volcano within a radius of 15 miles and along the North Fork of the Toutle River," he said. "There is no indication that mudflows have occurred. However, seismic activity continues at this time and mudflows are a possiblity if an explosive type of eruption were to occur."

Earlier, the volcano shot two towering plumes of steam and ash four and five miles high before settling into a pattern indicating the movement of lava or gas, or both, deep inside the mountain.

"It means an eruption is quite likely at any point," spokesman A.B. Adams of the University of Washington geophysics program said, referring to the seismic readings.