:Product: 3-Day Forecast :Issued: 2024 Dec 13 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 2 (below NOAA Scale levels). The greatest expected 3 hr Kp for Dec 13-Dec 15 2024 is 2.67 (below NOAA Scale levels). NOAA Kp index breakdown Dec 13-Dec 15 2024 Dec 13 Dec 14 Dec 15 00-03UT 0.33 1.67 2.33 03-06UT 0.33 1.67 2.00 06-09UT 1.67 1.33 1.67 09-12UT 1.67 1.33 1.33 12-15UT 1.33 1.67 2.00 15-18UT 1.33 1.33 2.00 18-21UT 1.33 1.33 2.67 21-00UT 1.33 1.33 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 Dec 13-Dec 15 2024 Dec 13 Dec 14 Dec 15 S1 or greater 5% 5% 5% Rationale: No S1 (Minor) or greater solar radiation storms are expected. No 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 2024 1743 UTC. Radio Blackout Forecast for Dec 13-Dec 15 2024 Dec 13 Dec 14 Dec 15 R1-R2 55% 55% 55% R3 or greater 5% 5% 5% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely on 13-15 Dec based primarily on the flare potential of Regions 3917, 3920 and 3922.