The blast of solar wind (known as a coronal mass ejection) associated with the second strongest flare unleashed by the sun in the last five years has reached Earth. The storm arrived less intense than forecast, but it may have yet to pack its biggest punch.
The geomagnetic storm blew in at 5:45 a.m. EST this morning. It produced a “pretty good shock, a good sign the storm was energetic,” said Joe Kunches, NOAA space weather scientist.
For the moment, its intensity is minor, or rated at G1 on NOAA’s five-point scale. A storm of this magnitude typically produces impacts primarily at high latitudes, poleward of 60 degrees. And they are fairly common, Kunches said.
“We can expect a couple hundred of these over the next 11 years,” Kunches said.
But NOAA’s Space Weather Prediction Center (SPWC) says the storm, expected to last about a day, may grow stronger.
“So far the orientation of the magnetic field has been opposite of what is needed to cause the strongest storming,” it said. “As the event progresses, that field will continue to change.”
NOAA says its prediction made yesterday that the storm will reach the strong G3 intensity looks “justified.”
But Kunches emphasized the uncertainty in these forecasts. Detailed information about the orientation of a solar storm relative to the Earth’s magnetic field is unknowable until the storm is essentially striking.
“[Predicting solar storms] is like predicting a hurricane without knowing the barometic pressure in the center of the storm,” he said.
If the storm intensifies, NOAA says most impacts should remain at high latitudes. In a Facebook update, the SWPC wrote:
The main impacts from this event will be to HF [ high frequency] communication in the polar regions, rendering HF unusable at the highest latitudes. There are also several confirmed reports of commercial airlines avoiding the polar routes because of the disruption to HF communication.
SpaceWeather.com indicates aurora were as far south as the northern Great Lakes very early this morning, and features a photograph from Murmansk Russia. Auroras should be visible tonight, with high latitudes again the favored location
Link: NOAA Auroral Forecast
The planetary index (Kp) - which serves as a predictor of the southern extent of auroral activity - is currently around 5 - meaning the likelihood of auroras is primarily north of the U.S.-Canadian border. If the index increases, aurora activity could dip into the mid-latitudes.
Optimal aurora viewing requires clear skies and minimal light pollution. The best time to view auroras is typically within an hour of local midnight, NOAA’s Kunches said. Ideally, moonlight is minimal too - but, right now, the moon is near full.
The University of Alaska posted the following aurora forecast, which is somewhat more aggressive than SpaceWeather.com’s and NOAA’s (which indicate aurora activity most likely at high latitudes):
Auroral activity will be high(+). Weather permitting, highly active auroral displays will be visible overhead from Inuvik, Yellowknife, Rankin and Igaluit to Vancouver, Helena, Minneapolis, Milwaukee, Bay City, Toronto, Montpelier, and Charlottetown, and visible low on the horizon from Salem, Boise, Cheyenne, Lincoln, Indianapolis and Annapolis
The current solar storm activity has arisen from the active sunspot region 1429, currently facing the Earth dead-on.
“We’re right down main street [from the active region],” Kunches said. “A further eruption could be very problematic for us.”
But over the last day there have been no new eruptions of significance Kunches said.