@ FXXX10 KWNP 200031 DAYTDF :Product: 3-Day Forecast :Issued: 2026 May 20 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 4 (below NOAA Scale levels). The greatest expected 3 hr Kp for May 20-May 22 2026 is 3.67 (below NOAA Scale levels). NOAA Kp index breakdown May 20-May 22 2026 May 20 May 21 May 22 00-03UT 2.67 2.67 2.67 03-06UT 2.33 2.00 3.67 06-09UT 2.00 2.33 2.00 09-12UT 2.00 2.33 0.67 12-15UT 2.00 2.33 1.67 15-18UT 2.00 2.33 1.67 18-21UT 2.00 2.33 2.33 21-00UT 2.00 2.67 2.33 Rationale: No G1 (Minor) or greater geomagnetic storms are expected. A solar sector boundary crossing and positive polarity CH HSS influences are possible through 21-22 May. B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-19 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for May 20-May 22 2026 May 20 May 21 May 22 S1 or greater 5% 5% 5% Rationale: No S1 (Minor) or greater solar radiation storms are expected. C. NOAA Radio Blackout Activity and Forecast No radio blackouts were observed over the past 24 hours. Radio Blackout Forecast for May 20-May 22 2026 May 20 May 21 May 22 R1-R2 20% 20% 25% R3 or greater 5% 5% 5% Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio blackouts through 21 May, increasing to a chance on 22 May. R3 (Strong) or greater events are not expected.