Strong geomagnetic storm (G3) was registered globally on April 19th with NOAA Kp reaching 7 in the interval between 18:00 and 21:00 UTC. The geomagnetic storm was triggered by enhanced solar wind conditions likely due to the arrival of a partial halo CME which lifted off the solar surface on April 15th, possibly combined with an expected CIR in front of a high speed stream arrival. Locally over Belgium, only minor geomagnetic storm conditions were observed (K-Bel = 5). Further minor to moderate storm conditions may be expected in the coming hours.

A halo or partial-halo CME was detected with the following characteristics: t0 | dt0| pa | da | v | dv | minv| maxv| 2024-04-16T10:24:07.520 | 1.0 | 236 | 178 | 1690 | 182 | 1358 | 2011 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 was at moderate levels, with multiple C-class flares and one M-class flare recorded in the past 24 hours. The largest flare of the period was an M1.0 flare, peaking at 13:06 UTC on Apr 19, associated with NOAA AR 3647 (beta-delta class). There are currently 14 numbered active regions on the visible disk. NOAA AR 3639 (beta-gamma) is the largest region on disk but was inactive. NOAA AR 3635 is expected to rotate over the west limb in the next hours. Other regions on the disc have simple configuration of their photospheric magnetic field (alpha and beta). The solar flaring activity is expected to be at moderate levels over the next 24 hours, with M-class flares possible and a low chance for X-class flare. No Earth-directed CMEs have been detected in the available coronagraph imagery over the past 24 hours. Over the past 24 hours the greater than 10 MeV GOES proton flux was at nominal levels and is expected to remain so with possible enhancements in case of increased levels of solar activity over the next days. The greater than 2 MeV electron flux, as measured by the GOES-16 satellite, remained below the 1000 pfu threshold. It is expected to remain below the threshold during the next 24 hours. The 24 hour electron fluence was at normal levels and is expected to remain at these levels for the following 24 hours.

Geomagnetic conditions reached strong storm levels globally (NOAA-Kp = 7) between 18:00 and 21:00 UTC on Apr 19. Locally over Belgium, only minor geomagnetic storm conditions were observed (K-Bel = 5). Conditions then reduced to quiet to unsettled levels. The strong storm period was reached due to the prolonged period of negative Bz. Predominantly unsettled geomagnetic conditions are expected on Apr 20-21 with a chance of reaching active and minor storm conditions due to expected HSS arrival and potential CMEs arrivals. Over the past 24 hours, the solar wind parameters were slightly disturbed under the ICME influence. The total magnetic field reached 18 nT at 14:13 UTC on April 19, later decreasing to the values around 5 nT. The solar wind speed ranged between 400 km/s and 550 km/s. The southward component of the interplanetary magnetic field fluctuated between -16 nT and 7 nT. The interplanetary magnetic field phi angle varied between being directed towards the Sun to being directed away from the Sun. The effects of the CME are expected to slowly wane in the next 24 hours with a chance of a further enhancement on Apr 20 - Apr 21 due to the arrival of a high-speed stream from a negative polarity coronal hole and anticipated arrival of CMEs from Apr 17 - Apr 18, however with low confidence.