Northern lights expected Saturday-Sunday

NOAA’s Space Weather Prediction Center said Sunday that a minor G1 geomagnetic storm was forecast to continue through May 17, keeping open the possibility of aurora sightings across parts of the northern United States and Canada. The agency’s public dashboard showed G1 conditions in its outlook for both May 17 and May 18, after stronger activity was observed earlier in the prior 24 hours. EarthSky, citing incoming solar wind, said Saturday that storming had already arrived and could continue through the weekend. The forecasts pointed skywatchers to dark locations and late-night to early-morning hours, when aurora is typically easiest to spot. ### How strong is the storm expected to be? NOAA’s weekly advisory outlook said G1, or minor, geomagnetic storm levels were likely on May 15-17 because of the influence of a coronal hole. The same advisory said no other space weather storms were expected during that seven-day outlook window. NOAA’s three-day geomagnetic forecast, issued at 2205 UTC on May 16, put the probability of a minor storm at 40% on both May 17 and May 18. (swpc.noaa.gov) The same forecast assigned a 25% chance of a moderate storm on those two days and a 10% chance of strong-to-extreme storm levels on May 17, falling to 1% by May 19. ### Why were people talking about G2 conditions too? (swpc.noaa.gov) NOAA’s aurora dashboard said the greatest observed three-hour Kp over the previous 24 hours was 6, which corresponds to G2, or moderate, storm conditions. The same dashboard said the greatest expected three-hour Kp for May 17 through May 19 was 5.00, which corresponds to G1 conditions. EarthSky said on May 16 that the expected G2 geomagnetic storm had arrived as solar wind increased to high levels. (swpc.noaa.gov) EarthSky added that storming might continue through the weekend, which helps explain why some forecasts and social media posts referred to both G1 and G2 levels in the same stretch of time. ### When were the better viewing windows? (swpc.noaa.gov) NOAA’s forecast breaks geomagnetic activity into three-hour blocks in Universal Time, not local clock times. For May 18 UTC, which overlaps with Sunday morning in the eastern United States, the agency forecast Kp 5.00 during the 15-18 UTC block, while earlier overnight blocks were lower. The practical viewing window for aurora is still after dark, and forecasters generally direct viewers to the late-night and pre-dawn hours rather than daylight periods. (earthsky.org) NOAA’s aurora dashboard says it provides predictions for “tonight and tomorrow night” and short-term estimates for the next 30 minutes, making it the main live tool for checking whether activity is lining up with local darkness. (swpc.noaa.gov) ### Where were the best odds of seeing it? NOAA’s aurora dashboard said it is designed to show “when and where” the aurora may be visible and provides a viewline forecast for tonight and tomorrow night. In practice, the farther north a viewer is and the darker the sky, the better the chance of seeing the lights. Dark-sky conditions matter because geomagnetic activity alone does not guarantee a visible display at ground level. (swpc.noaa.gov) EarthSky said viewers should look from dark locations, and NOAA’s dashboard directs users to near-real-time maps rather than a fixed state-by-state list because visibility shifts with solar wind and magnetic conditions. ### What should viewers watch next on Sunday? (swpc.noaa.gov) NOAA’s aurora dashboard updates with current solar wind speed, magnetic field readings and short-range aurora maps, and the version captured Sunday showed solar wind at 657 kilometers per second. The same page also listed the latest observed space weather status and the expected Kp breakdown by time block through May 19. (earthsky.org) May 18 is the next date in NOAA’s three-day forecast with a 40% chance of minor storm conditions and a 25% chance of moderate storm conditions. For viewers in the United States, the next step is to check NOAA’s aurora dashboard after dark Sunday and compare the live map with local cloud cover before heading out. (swpc.noaa.gov 1) (swpc.noaa.gov 2)