Summary and Forecast

Solar Summary

(last updated 19 May 2026 23:30 UT)

Activity 19 May: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 19 May: 106/55

Solar Forecast

(last updated 19 May 2026 23:30 UT)

20 May 21 May 22 May Activity R0, chance of R1 R0, chance of R1 R0, chance of R1 Fadeouts None expected None expected None expected 10.7cm/SSN 110/60 110/60 108/58 COMMENT: Solar flare activity on UT day 19-May was at the R0 level, with no significant flaring activity. There are currently five numbered sunspot regions visible on the solar disk. Active Region (AR) 4441 (N08W13, beta) is the largest region on the disk and has shown mild decay in its intermediate spots. AR 4436 (N20W63, beta) has exhibited mild growth in its trailer spots. Region 4443 (S16E36, alpha) has shown mild spot development. All other sunspot regions are either stable or in decay. Solar flare activity is expected to be at the R0 level over 20-22 May, with a chance of R1. S0 solar proton conditions were observed on UT day 19-May. S0 solar proton conditions are expected over 20-22 May. No Earth-directed coronal mass ejections (CMEs) have been observed. A northwest-directed CME was observed in LASCO C2 coronagraph imagery at 19/1101UT. Modelling indicates this CME is not geoeffective. The solar wind speed on UT day 19-May initially increased due to a step increase observed at 19/0632UT, likely indicative of a weak CME arrival. The solar wind speed decreased over the remainder of the UT day. The solar wind ranged from 495 to 625 km/s and is currently near 500 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 8 nT and the north-south IMF component (Bz) range was -7 to +5 nT. The solar wind speed is expected to decrease over 20-22 May.

Solar Activity levels are explained in the SWS Solar Terrestrial Glossary.