Far-Side CME Triggers S1 Solar Radiation Storm, Leaving 10% Risk on May 27
Updated
Updated · The Watchers · May 27
Far-Side CME Triggers S1 Solar Radiation Storm, Leaving 10% Risk on May 27
3 articles · Updated · The Watchers · May 27
Summary
GOES-19 data showed high-energy protons briefly hit NOAA’s S1 minor solar radiation storm threshold on May 26, then dropped below storm levels by May 27.
The burst followed a large partial halo coronal mass ejection first detected at 22:00 UTC on May 25 from the Sun’s far side, with proton decline slowing after 17:15 UTC on May 26.
NOAA still forecast a 10% chance of another S1-or-stronger event on May 27, easing to 5% on May 28 and May 29 as elevated background proton levels lingered.
Solar activity otherwise stayed low: Region 4446 produced a C9.7 flare at 12:38 UTC on May 26, and a Type II radio burst suggested a 650 km/s shock, while another faint CME remained under analysis.
S1 is the lowest radiation-storm category and mainly brings minor high-frequency radio effects in polar regions; stronger S2 to S5 storms can disrupt satellites, navigation, aviation and raise radiation exposure.