Spectacular Northern Lights illuminated much of America overnight Nov 11-12 with minimal warning, and another powerful coronal mass ejection approaching Earth could trigger additional displays Wednesday Nov 12, though forecasters acknowledge significant prediction challenges, USA TODAY and AccuWeather reported.
Space weather forecasting presents unique difficulties because scientists must rely on observations from 93 million miles away rather than nearby measurements, with aurora chaser Melissa F. Kaelin calling it "an emerging science" where "humans still have a lot to learn about space weather," USA TODAY noted. Bill Murtagh, program coordinator at the Space Weather Prediction Center, told USA TODAY that "There are so many uncertainties, it makes it difficult to predict," acknowledging forecasters are "we are decades behind the forecast capabilities of our colleagues in meteorology."
Wednesday's most intense geomagnetic activity may peak during midday across North America, though if conditions persist past nightfall, aurora borealis could become visible from Alabama and Northern California northward, with northern tier states showing highest probability, AccuWeather reported. Coronal mass ejections change trajectory and strength during their Earth journey, and solar wind speed errors of just 1% to 2% translate into one to two hour arrival time differences, creating substantial forecast impacts, according to the Space Weather Prediction Center and CBS News.
Shawn Dahl, service coordinator at the Space Weather Prediction Center, told AccuWeather Nov 11 that the Veterans Day solar flare ranked among the most powerful of Solar Cycle 25, explaining "This was the 6th largest solar flare thus far in Solar Cycle 25 and perhaps among the top 39 solar flares recorded in the space age. It was less energetic than the October flare, but this time it is in a much more favorable position for a solar radiation storm (which we have in progress), and the associated CME is being evaluated at this time." Current solar activity represents the peak of the 11-year Solar Cycle 25, when eruptions reach maximum frequency.
Space weather warnings issued by the Met Office indicate "aurora displays will be visible across parts of the UK" Wednesday night Nov 12 into Thursday morning, with "Vibrant displays are set to be possible again" in northern Britain and possible sightings extending across England and Wales, though clouds may limit visibility. The Met Office issued both "extreme" and "severe" geomagnetic storm alerts, including a severe G5 storm notification from noon Wednesday through 11:59 pm Thursday Nov 13.
Red alert G5 conditions, the highest storm category, could enable aurora visibility throughout all of Britain, with Met Office aurora maps showing red-orange coverage across northern regions and green ovals indicating southern visibility prospects, the Met Office reported. Optimal viewing falls between 9 pm and 3 am Wednesday night, with forecasted peak activity around midnight.
The Met Office stated in its Wednesday forecast: "Two (Coronal mass ejections) CMEs arrived late on the 11 Nov with a further CME expected on the 12 Nov. These CMEs are associated with Strong class flares and increase in speed with each event. Aurora is expected across parts of northern UK and similar geomagnetic latitudes, with a chance of sighting further south across England and Wales. Cloud cover however will likely limit sightings, with the best of any breaks being towards southeast England (where the aurora is less likely) or perhaps the far north Scotland (aurora is more likely). Enhanced aurora may continue overnight Thursday, this is currently lower confidence though but more cloud breaks across parts of England and Wales and far North Scotland may lead to more sightings. Activity currently expected to then decline through the period, but it should be noted the area responsible for these CMEs is still present on the disc and this forecast may change." Clear skies prove essential for viewing since aurora displays occur hundreds of kilometers above cloud level, the Met Office added.
