Article Posted on : - Mar 11, 2012

WASHINGTON (AFP): A strong space weather storm packed a late punch overnight and ended up being the most significant geomagnetic event since 2004, US experts said, warning more disruption was coming this weekend.

The fusillade of radiation from the Sun caused limited power grid upsets, forced airlines to reroute around the poles and sparked vivid displays of the Northern Lights in some parts of the world.

The event began late Tuesday with a series of explosions on the Sun that sent charged particles hurtling toward Earth, but the storm appeared to fizzle on arrival Thursday, causing no power outages or problems with GPS navigation systems as expected.

Conditions changed late Thursday that boosted the ferocity of the storm, raising it to the initially forecast G3 level of "strong" on a scale of one to five, said yesterday Bob Rutledge who heads the space weather forecast office at the National Oceanic and Atmospheric Administration (NOAA).

"We ended up getting some of the strong storming that was expected," he said explaining that change was due to a flip in the magnetic field inside the coronal mass ejection that burst off from the Sun.

"When you look at the storm overall for length and strength, it is arguably the strongest storm since November 2004," he said.

People across the northern US states of Wisconsin, Michigan and Washington reported seeing the nighttime light show caused by the aurora borealis when highly charged particles interact with the Earth's magnetic field, creating a colorful glow.

And although power industry operators have "certainly seen these disturbances on their systems... it should all be well within what they are capable of handling," Rutledge added.

As the current storm wound down Friday, Rutledge warned there was a potential for more disruptions by tomorrow due to a flare overnight from the same region on the Sun, known as 1429, that has been acting up since early in the week.