Summary and Forecast

Solar Summary

(last updated 20 Mar 2025 23:31 UT)

Activity 20 Mar: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 20 Mar: 170/124

Solar Forecast

(last updated 20 Mar 2025 23:31 UT)

21 Mar 22 Mar 23 Mar Activity R0-R1 R0-R1 R0-R1 Fadeouts Possible Possible Possible 10.7cm/SSN 170/124 165/119 155/109 COMMENT: Solar activity on UT day 20-Mar was R0, with no significant solar flares. There are currently nine numbered sunspot regions on the solar disk. AR4034 (S17E03, beta) and AR4035 (N15E10, beta) have shown some minor growth, but all other sunspots are either stable or in decay. Solar activity is expected to be R0-R1 over 21-23 Mar. Two CMEs were observed off the western limb on UT day 20-Mar; both are likely to originate from ex-region AR4018, now expected to be more than 10 degrees over the western limb. These CMEs are therefore not expected to be geoeffective. The CME featured in yesterday's report has been further analysed to suggest that it may pass nearby the Earth late on 22-Mar or else early 23-Mar, but is not expected to have a full impact. S0 solar radiation storm conditions were observed on UT day 20-Mar, although there was a small proton response mostly likely from the CME activity off the western limb. S0 solar radiation storm conditions are mostly expected over 21-23 Mar. The solar wind was near background conditions on UT day 20-Mar. The peak total interplanetary field strength (IMF, Bt) was 6 nT and the north-south IMF componant range (Bz) was +4 to -4 nT. The solar wind speed was on a slow decline and ranged from 500 km/s to 400 km/s. The solar wind speed is expected to be at background levels on 21-Mar, and may become mildly disturbed on 22-Mar due to a CME passing nearby. Connection to an equatorial coronal hole is expected by 23-Mar, increasing the solar wind speed from then. The CME from 16-Mar likely passed nearby the Earth on 19-Mar and is no longer in the forecast.

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