####018002373#### FXXX10 KWNP 260031 DAYTDF :Product: 3-Day Forecast :Issued: 2026 Apr 26 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 # # 3-Day Forecast # A. NOAA Geomagnetic Activity Observation and Forecast The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA Scale levels). The greatest expected 3 hr Kp for Apr 26-Apr 28 2026 is 4.67 (NOAA Scale G1). NOAA Kp index breakdown Apr 26-Apr 28 2026 Apr 26 Apr 27 Apr 28 00-03UT 4.67 (G1) 3.67 2.33 03-06UT 4.33 3.00 2.00 06-09UT 3.33 2.67 2.00 09-12UT 3.33 2.33 2.00 12-15UT 2.33 2.00 2.33 15-18UT 2.33 2.33 2.00 18-21UT 3.00 3.33 2.00 21-00UT 3.33 3.33 2.00 Rationale: Isolated G1-G2 (Minor-Moderate) geomagnetic storming conditions are possible (G1 likely with a chance for G2)early 26 Apr in response to the arrival of the glancing CMEs. B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for Apr 26-Apr 28 2026 Apr 26 Apr 27 Apr 28 S1 or greater 10% 10% 10% Rationale: There is a chance to exceed the S1 (Minor) solar radiation storm thresholds due to the flare potential of Region 4419 further beyond the western limb, and Region 4420 near the central solar meridian. C. NOAA Radio Blackout Activity and Forecast Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Apr 25 2026 0759 UTC. Radio Blackout Forecast for Apr 26-Apr 28 2026 Apr 26 Apr 27 Apr 28 R1-R2 55% 55% 55% R3 or greater 15% 15% 15% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a slight chance for R3 (Strong or greater) events through 28 Apr, primarily driven by the complexity of Regions 4420, 4423, and 4425. ####018004323#### FXXX12 KWNP 260031 DAYDIS :Product: Forecast Discussion :Issued: 2026 Apr 26 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 was at moderate levels during the reporting period. The largest events were an M1.3/Sf flare at 25/0759 UTC from Region 4423 (S05E18, Dai/beta-gamma-delta) and an impulsive M1.1/Sf flare at 25/1430 UTC from Region 4425 (N05E66, Eac/beta-gamma). While Regions 4423 and 4425 were the primary drivers of activity, isolated C-class flares were observed from Regions 4420 (N16W01, Fki/beta-gamma-delta) and 4424 (N16E33, Dsi/beta). A bright and partially obscured C3.8 flare was observed from Region 4419 (N17, L=316) as it rotated over the western limb. There are currently eight numbered regions on the visible disk. Region 4419 rotated beyond the western limb during the period. Region 4420 showed flux emergence in its intermediary spots, increased shear in the trailing portion, and growth in overall area. Region 4423 showed consolidation in both the leader and trailer spots and became less fragmented. Region 4424 showed growth in its intermediate spots, alongside consolidation in the trailing spot. Region 4425 rotated further into view, though limb proximity continues to hinder full characterization of its extent and magnetic complexity. Region 4426 (N12W37, Axx/alpha) lost its trailing spot and became a unipolar group, and Region 4427 (S30E67, Axx/alpha) was numbered during the period as an unremarkable unipolar group. All other regions were stable or in slight decay. A narrow eruption likely associated with the M1.1 flare from Region 4425 was observed off the eastern limb. Modeling indicates the ejecta will pass well behind Earth. No other CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to be at low levels, with M-class flares (R1-R2-Moderate) likely, and a chance for X-class (R3/Strong or greater) flares through 28 Apr, primarily driven by the complexity of Regions 4420, 4423, and 4425. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit was at low to moderate levels with a peak of 403 pfu at 25/1910 UTC. The greater than 10 MeV proton flux at geosynchronous orbit was slightly elevated, but remained near background levels. .Forecast... The greater than 2 MeV electron flux is expected to be at moderate to high levels through 28 Apr. The greater than 10 MeV proton flux is expected to remain at background levels, though there is a decreasing chance for levels to exceed S1 (Minor) solar radiation storm thresholds due to the flare activity of now-departed Region 4419 and Region 4420 as it approaches central solar meridian. Solar Wind .24 hr Summary... Solar wind parameters were marginally enhanced through the period, with speeds initially near 450 km/s before trending toward 350 km/s. Conditions became increasingly perturbed late in the period, signaling the passage of a transient structure that is possibly the glancing influence of the 23 Apr CME. Total magnetic field (Bt) averaged near 8 nT before peaking at 12 nT near the end of the UT day. This peak in Bt coincided with a southward deflection of the Bz component to -9 nT and an increase in solar wind speed to 450 km/s. This disturbance was characterized by a distinct density enhancement and a transient rotation in the phi angle, which was otherwise predominantly positive throughout the period. .Forecast... Further enhancements in the solar wind environment are anticipated 26-27 Apr due to anticipated arrival of further glancing influences from the 23 Apr and 24 Apr CMEs. Geospace .24 hr Summary... The geomagnetic field was quiet to unsettled. .Forecast... Isolated G1 (Minor) geomagnetic storming conditions are possible late on early 26 Apr in response to the arrival of the glancing CMEs. Quiet to unsettled conditions are then anticipated 27-28 Apr as CME influences subside.