The geomagnetic storm that forecasters predicted could reach "strong" G-3 intensity is currently only a "minor" G-1 event, with minimal effects expected on Earth.
"This is not a terribly strong event," said physicist and NOAA space weather scientist Joseph Kunches.
Turns out, predicting space weather is tough.
"We did estimate where the pitch was going and when it was going over the plate, but we missed the spin on the ball," said Kunches, using a baseball analogy.
A G-1 or "minor" storm is at the bottom of a scale that goes up to G-5, or "extreme".
A G-1 storm is capable of producing weak fluctuations in the power grid but generally has minor impacts on satellites orbiting the Earth. GPS and radio communications can have intermittent problems, and the northern lights might be seen as far south as Michigan and Maine. (You can get an idea for where aurora might be visible here: http://helios.swpc.noaa.gov/ovation/ )
The storm - which was born from a massive solar flare that erupted Tuesday - is still passing Earth, and could potentially still reach G-2 or G-3 levels before it fades sometime Friday, Kunches said.
"We really worry about crying wolf," said Kunches. "In any forecasting activity, you have to seriously consider the false alarm rate and the cry wolf rate so you don't erode your credibility."
Forecasters at NOAA's Space Weather Prediction Center say there is still potential for trouble over the next few days. The sunspot region known as AR 1429 that that unleashed the latest geomagnetic storm is still active, and aimed toward Earth.
"A further eruption could be very problematic," Kunches said. "We could go through the same drill that we're going through right now. Probably through the weekend it's in a prime location and then it becomes less problematic through the next week."
The impact from geomagnetic storms can be serious. Fall of 2003 saw an intense period of solar activity that included two "extreme" G-5 storms. Transformer problems caused blackouts in Europe. Astronauts on the International Space Station were told to take cover. Deep space missions like the Mars Odyssey developed problems and had to be rebooted, while Japan's $640 million ADEOS-2 was a total loss.
"Airlines took unprecedented actions in their high latitude routes to avoid the high radiation levels and communication blackout areas. Rerouted flights cost airlines $10,000 to $100,000 per flight," according to a NOAA report.
A 1989 solar storm knocked out power to 6 million people in Canada's Quebec Province and affected power utilities in a few U.S. states.