:Product: 3-Day Forecast :Issued: 2023 Mar 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 4 (below NOAA Scale levels). The greatest expected 3 hr Kp for Mar 23-Mar 25 2023 is 6.00 (NOAA Scale G2). NOAA Kp index breakdown Mar 23-Mar 25 2023 Mar 23 Mar 24 Mar 25 00-03UT 1.33 5.33 (G1) 3.67 03-06UT 1.67 5.67 (G2) 4.67 (G1) 06-09UT 3.67 6.00 (G2) 4.33 09-12UT 4.00 4.33 4.00 12-15UT 4.67 (G1) 4.00 4.00 15-18UT 3.00 4.00 4.00 18-21UT 4.00 3.00 4.33 21-00UT 5.00 (G1) 3.33 4.33 Rationale: G1 (Minor) storm levels are expected following the possible glancing influence of the 20 Mar CME or the anticipated earlier arrival of a CIR ahead of a recurrent, negative polarity CH HSS. Nearby transients may further elevate conditions on the 23rd depending on how they interact with this enhanced solar wind environment. G2 (Moderate) geomagnetic storm levels are likely to be reached on 24 Mar with the onset of the CH HSS. G1 (Minor) storm levels remain likely into 25 Mar. B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-16 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for Mar 23-Mar 25 2023 Mar 23 Mar 24 Mar 25 S1 or greater 1% 1% 1% 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 No radio blackouts were observed over the past 24 hours. Radio Blackout Forecast for Mar 23-Mar 25 2023 Mar 23 Mar 24 Mar 25 R1-R2 10% 10% 10% R3 or greater 1% 1% 1% Rationale: There is a slight chance for R1 (Minor) radio blackouts over 23-25 Mar.