A full halo CME was first seen at 05:36 UT on LASCO C2, originating from an eruption close to NOAA AR 3683 (located at the southwest, at S25W60), associated with a C6.7 flare. The CME is fast, early speed estimates are around 1500 km/s, but more images are needed for a better estimation. The bulk of the CME is directed to the southwest, but a glancing blow can be expected on 22 May. Due to the location of the event and the speed of the CME, a proton event may occur in the coming hours.

A halo or partial-halo CME was detected with the following characteristics: t0 | dt0| pa | da | v | dv | minv| maxv| 2024-05-20T05:36:07.525 | 1.0 | 239 | 180 | 1564 | 235 | 1079 | 1956 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

There are six visible ARs on the solar disk. Flaring activity has been low, only C-class flares were observed in the last 24 hours. The strongest one was a C4.8 flare from NOAA AR 3683 (beta magnetic field configuration). NOAA AR 3685 has beta-gamma magnetic field configuration and has evolved in size and complexity. More C-class flares will occur and M-class flares can be expected in the next 24 hours. No Earth directed CME has been observed in the last 24 hours. After further analysis, the CME from 20 May is not expected to affect the Earth. The 10 MeV GOES-18 proton flux was below threshold in the past 24 hours, it is expected to remain so. The greater than 2 MeV electron flux from GOES 16 was below the threshold level in the last 24 hours. It is expected to remain below the threshold during the next 24 hours. The electron fluence was at normal levels for the last 24 hours and is expected to remain so.

Geomagnetic conditions have been quiet in the last 24 hours (Kp and K_BEL up to 2). If we see a glancing blow from the 17 May CME (low chances), disturbed conditions may occur, otherwise quiet conditions can be expected for the next 24 hours. The solar wind at the Earth is slow, with speeds around 380 km/s and interplanetary magnetic field around 6 nT. There are low chances of a glancing blow from the CME on 17 May, otherwise slow wind conditions can be expected for the next 24 hours.