:Product: 3-Day Forecast :Issued: 2013 May 22 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 May 22-May 24 2013 is 4 (below NOAA Scale levels). NOAA Kp index breakdown May 22-May 24 2013 May 22 May 23 May 24 00-03UT 4 3 3 03-06UT 2 4 3 06-09UT 2 3 1 09-12UT 2 3 1 12-15UT 2 3 1 15-18UT 3 3 1 18-21UT 3 3 1 21-00UT 3 3 1 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-13 over the past 24 hours, was below S-scale storm level thresholds. Solar Radiation Storm Forecast for May 22-May 24 2013 May 22 May 23 May 24 S1 or greater 15% 15% 15% 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 May 22-May 24 2013 May 22 May 23 May 24 R1-R2 50% 50% 50% R3 or greater 15% 15% 15% Rationale: Solar activity is expected to be below NOAA Scale thresholds during the period (22 - 24 May). There is a chance for an M-class (NOAA Scale R1- Minor) flare and a slight chance for an X-class (NOAA Scale R3- Strong) flare as Region 1748 continues its migration across the visible disk and Region 1755 migrates towards center disk.