The greater than 10 MeV proton flux as measured by GOES 16 and GOES 18 has now exceeded the 10 pfu threshold marking a minor solar radiation storm. The proton flux levels were increased as a result of the solar activity on Sept 14th with X4.5 flaring from NOAA 3825 (beta-gamma) and associated halo coronal mass ejection (CME), which has now arrived to Earth. The greater than 10 MeV proton flux levels are expected to remain elevated on Sept 17th and start declining on Sept 18th in case of no new strong eruptive solar activity.

A class X4.5 solar X-ray flare occurred on 2024/09/14 with peak time 15:29UT

A halo or partial-halo CME was detected with the following characteristics: t0 | dt0| pa | da | v | dv | minv| maxv| 2024-09-13T11:36:07.379 | 12.0 | 294 | 226 | 389 | 496 | 130 | 1683 t0: onset time, earliest indication of liftoff dt0: duration of liftoff (hours) pa: principal angle, counterclockwise from North (degrees) da: angular width of the CME (degrees), v: median velocity (km/s) dv: variation (1 sigma) of velocity over the width of the CME mindv: lowest velocity detected within the CME maxdv: highest velocity detected within the CME

Solar flaring activity over the past 24 hours remained at low levels with background low C-class flaring. The largest activity was C3.9-flare with peak time 12:33 UTC on Sept 17th associated with NOAA AR 3824 (beta-gamma). There are seven numbered regions on the visible solar disc with NOAA AR 3825 (beta-gamma) being the largest and most complex region, which exhibited further flux emergence and magnetic field reconfiguration. Most of the flaring activity was produced by NOAA AR 3828 (alpha), NOAA AR 3824 and NOAA AR 3825. The solar flaring activity is likely to be at low to moderate levels over the coming days with 60% chances of M-class flares and 15% chances for isolated X-class flaring. No Earth-directed coronal mass ejections (CMEs) have been detected in the available coronagraph imagery over the past 24 hours. A flat and narrow positive polarity mid-latitude coronal hole continues to reside on the central meridian. A mild high speed stream associated to this coronal hole could reach Earth on Sept 20th through Sept 22nd. Over the past 24 hours the greater than 10 MeV GOES proton flux has gradually decreased from minor radiation storm levels to below the 10 pfu threshold. The greater than 10 MeV GOES proton flux is expected to fully return towards backgrounds levels over the next 24 hours. The greater than 2 MeV electron flux as measured by GOES 16 and GOES 18 were below the 1000 pfu threshold over the past 24 hours and is expected to remain so over the next 24 hours. The 24h electron fluence was nominal levels and is expected to remain so in the next 24 hours.

The geomagnetic conditions over the past 24 hours were predominantly quiet to active with a single moderate storm level as registered by the NOAA Kp index of 6- between 12:00 and 15:00 UTC on Sept 17th. Locally over Belgium only quiet to active conditions were observed. Mostly quiet to active geomagnetic conditions with small chances for isolated minor storms are expected over the next days with possible two mild high speed stream arrivals on Sept 18th - Sept 20th. Over the past 24 hours the solar wind parameters (ACE and DSCOVR) were indicative of the waning influence of an ICME arrival. The interplanetary magnetic field was mildly elevated reaching values of 12.9 nT with Bz as low as - 9.7 nT. The solar wind velocity varied in the range of 397 km/s to 557 km/s. The B field phi angle remained in the positive sector (directed away from the Sun). The solar wind conditions are expected to experience further decline towards nominal slow solar wind regime before registering slight enhancements from two possible high speed stream arrivals on Sept 18th - Sept 20th.