FXXX12 KWNP 210031 DAYDIS :Product: Forecast Discussion :Issued: 2026 Mar 21 0030 UTC # Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center # Product description and SWPC contact on the Web # http://www.swpc.noaa.gov/wwire.html # # Forecast Discussion # Solar Activity .24 hr Summary... Solar activity has been at very low levels for the past 24 hours. There are currently 2 numbered sunspot regions on the disk. Region 4397 (N18E42, Cao/beta) underwent some minor evolution as its leading penumbra began to mature. Region 4392 (S16W40, Cso/beta) exhibited decay in its leading spots, and remained relatively quiet. A full halo CME was observed in LASCO C2 coronagraph imagery beginning just after 20/1336 UTC. Analysis of GOES SUVI imagery indicates this event to have originated from the far side of the Sun. .Forecast... Solar activity will likely reach periods of low activity due to isolated C-class flares through 23 Mar. Energetic Particle .24 hr Summary... Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2,330 pfu at 20/0015 UTC. The greater than 10 MeV proton flux continued at background levels. .Forecast... The greater than 2 MeV electron flux is likely to decrease to normal-moderate levels on 21 Mar, due to CME arrival effects. Moderate to high levels are expected on 22-23 Mar. The greater than 10 MeV proton flux is expected to continue at background values. Solar Wind .24 hr Summary... Solar wind parameters reflected at least two CME arrivals with the first just after the turn of the UTC day around 20/0132 UTC and the second at approximately 20/2018 UTC. Solar wind speed reached a peak of 567 km/s at 20/2021 UTC. Total IMF reached 36 nT at 20/2100 UTC. The maximum southward component of Bz reached -28 nT at 20/2105 UTC. .Forecast... The solar wind environment is expected to remain enhanced through the forecast period. CME effects are expected to begin to wane by early on 22 Mar before an additional disturbance due to recurrent, negative polarity CH HSS influences arrive and continue through 23 Mar. Geospace .24 hr Summary... The geomagnetic field reached G2-G3 (Moderate-Strong) geomagnetic storm levels late in the period due to influence from a CME that left the Sun on 18 Mar. .Forecast... Geomagnetic field activity is expected to reach G3 (Strong) geomagnetic storm levels on early on 21 Mar due to ongoing CME effects. G1 (Minor) geomagnetic storming is likely to continue on into 22 Mar as recurrent, negative polarity CH HSS effects begin and CME effects wane. Unsettled to active conditions are then expected to prevail on 23 Mar as CH HSS effects continue.