FXXX10 KWNP 121231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Dec 12 1230 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 5 (NOAA Scale G1). The greatest expected 3 hr Kp for Dec 12-Dec 14 2025 is 4.33 (below NOAA Scale levels). NOAA Kp index breakdown Dec 12-Dec 14 2025 Dec 12 Dec 13 Dec 14 00-03UT 4.00 4.33 3.67 03-06UT 4.00 3.67 3.00 06-09UT 3.00 2.33 2.67 09-12UT 3.67 1.67 2.67 12-15UT 3.33 2.00 2.67 15-18UT 3.00 2.67 2.00 18-21UT 3.33 3.33 2.00 21-00UT 3.67 3.67 2.67 Rationale: No G1 (Minor) or greater geomagnetic storms are expected. 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 Dec 12-Dec 14 2025 Dec 12 Dec 13 Dec 14 S1 or greater 10% 5% 1% Rationale: There is a slight chance for S1 (Minor) or greater solar radiation storms 12-14 Dec. Little significant active region activity favorable for radiation storm production is forecast. C. NOAA Radio Blackout Activity and Forecast Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Dec 12 2025 0505 UTC. Radio Blackout Forecast for Dec 12-Dec 14 2025 Dec 12 Dec 13 Dec 14 R1-R2 65% 60% 55% R3 or greater 10% 5% 5% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a slight chance of R3 (Strong) or greater events, on 12-14 Dec.