:Product: Forecast Discussion :Issued: 2026 Apr 15 1230 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # Solar Activity .24 hr Summary... Solar activity was at very low levels with only isolated B-class flaring mostly from Region 4416 (N20W37, Dso/beta). There are currently four numbered regions on the visible disk. Region 4416 remains the largest group by area but exhibited signs of structural weakening, including flux submergence and a slight decay of its intermediary pores. Region 4419 (N13E58, Csi/beta-gamma) was the most complex group on the disk and showed flux emergence, growth, and divergence within its intermediary spots, leading to the development of a mixed-polarity gamma configuration. Region 4418 (S11W07, Bxo/beta) is trending toward plage with only two small bipolar pores remaining and Region 4415 (S18W05, Hsx/alpha) remained stable. CMEs observed in coronagraph imagery were determined to be directed away from Earth. .Forecast... Solar activity is expected to be at low to very low levels, with a slight chance for M-flares (R1-R2/Minor-Moderate) through 17 Apr. Energetic Particle .24 hr Summary... Electrons greater than 2 MeV at geosynchronous orbit reached high levels with a peak of 1705 pfu observed at 14/1445 UTC. The greater than 10 MeV proton flux was at background levels. .Forecast... The greater than 2 MeV electron flux is likely to reach high levels through 17 Apr. The greater than 10 MeV proton flux is expected to remain at background levels through 17 Apr. Solar Wind .24 hr Summary... Solar wind parameters reflected waning coronal hole high speed stream influences toward a nominal regime. Total magnetic field (Bt) remained steady and weak, generally ranging between 4 and 6 nT. The North-South (Bz) component was predominantly northward, though it exhibited occasional southward deviations with a maximum deflection of -4 nT. Solar wind speeds underwent a gradual, albeit erratic, decline from early-period highs near 420 km/s, to stabilize around 375 km/s by the end of the reporting period. The phi angle was predominantly oriented in a positive (away from the Sun) orientation. .Forecast... Solar wind parameters are expected to remain primarily near nominal levels through 16 Apr. Significant enhancements are anticipated on 17 Apr with the onset of a corotating interaction region (CIR) that will precede the arrival of a negative polarity high-speed stream (-CH HSS). Geospace .24 hr Summary... The geomagnetic field was quiet. .Forecast... The geomagnetic field is expected to be at mostly quiet to unsettled through 16 Apr. Activity is forecast to increase on 17 Apr to active levels in response to the arrival of the CIR and the subsequent onset of the -CH HSS.