:Product: 3-Day Forecast :Issued: 2026 Apr 23 1230 UTC # Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center # 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 23-Apr 25 2026 is 3.00 (below NOAA Scale levels). NOAA Kp index breakdown Apr 23-Apr 25 2026 Apr 23 Apr 24 Apr 25 00-03UT 2.33 2.33 2.33 03-06UT 3.00 2.67 2.67 06-09UT 2.33 2.67 2.33 09-12UT 2.00 1.67 2.00 12-15UT 0.67 1.33 1.33 15-18UT 2.00 2.00 1.67 18-21UT 2.67 2.00 2.00 21-00UT 3.00 2.33 2.67 Rationale: No G1 (Minor) or greater geomagnetic storms are expected. No significant transient or recurrent solar wind features are forecast. 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 23-Apr 25 2026 Apr 23 Apr 24 Apr 25 S1 or greater 10% 10% 10% Rationale: There is a slight chance for S1 (Minor) or greater solar radiation storms through 25 Apr. 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 23 2026 0848 UTC. Radio Blackout Forecast for Apr 23-Apr 25 2026 Apr 23 Apr 24 Apr 25 R1-R2 55% 55% 55% R3 or greater 20% 20% 20% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a slight chance for R3 (Strong) or greater blackouts on 23-25 Apr-primarily due to the flare potential from Regions 4419 and 4420, as well as activity from regions beyond the East limb.