PORTLAND - The northern lights may make a rare appearance in southern skies this weekend.
The aurora borealis may be visible on the Oregon horizon Friday and Saturday nights as streams of charged particles from the sun reach Earth.
Experts say there's also a possibility a solar storm could bedevil power grids and cause a temporary loss of electricity.
Satellite, radio and navigation transmissions also could be disrupted.
Auroras are more common in Alaska and other polar regions, but especially strong solar activity can cause them to be seen well south of their usual northern confines.
Mostly clear skies are forecast in Oregon the next few days, making viewing possible.
But even that's no guarantee. Jim Todd, planetarium manager at the Oregon Museum of Science and Industry, said auroras - and how impressive they'll be - are difficult to predict.
"We may be just on the edge of where an aurora will be visible," he said Thursday. "So we'll just have to wait and see."
Todd recommends would-be aurora watchers find a place away from city lights with a clear view of the northern horizon a few hours after sunset. He said the aurora may appear as a "low-grade glow" rather than spectacular green, red and blue displays.
"It may look like haze or fog - sometimes you can be looking right at it and not be aware that it's an aurora," Todd said.
"Just watch for a while and see whether it changes, which indicates it's an aurora you're looking at."
Two massive eruptions from dark sunspots labeled 484 and 486 on the sun's surface are responsible for the phenomenon. The explosions hurled coronal mass ejections into space - one on Wednesday and the other on Thursday morning.
Chris Balch, a scientist with the Space Environment Center in Boulder, Colo., a division of the National Oceanic and Atmospheric Administration, said the strongest solar event, which is expected to arrive today, could produce a moderate geomagnetic storm with a potential for affecting power grids.
"There's usually a two-day delay before these events reach Earth, so we'll continue to take measurements to get a better idea of their strength."