####018002234#### FXXX10 KWNP 211233 DAYTDF :Product: 3-Day Forecast :Issued: 2024 Apr 21 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 3 (below NOAA Scale levels). The greatest expected 3 hr Kp for Apr 21-Apr 23 2024 is 3.67 (below NOAA Scale levels). NOAA Kp index breakdown Apr 21-Apr 23 2024 Apr 21 Apr 22 Apr 23 00-03UT 3.00 2.33 2.33 03-06UT 3.00 2.67 3.00 06-09UT 3.33 2.00 3.67 09-12UT 3.33 2.33 3.67 12-15UT 3.67 2.00 2.67 15-18UT 2.67 1.67 2.67 18-21UT 2.00 1.67 2.67 21-00UT 2.00 2.33 3.00 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 Apr 21-Apr 23 2024 Apr 21 Apr 22 Apr 23 S1 or greater 15% 15% 15% Rationale: There is a slight chance for S1 (Minor) solar radiation storms over 21-23 Apr due to the flare potential of several active regions on the visible disk. C. NOAA Radio Blackout Activity and Forecast No radio blackouts were observed over the past 24 hours. Radio Blackout Forecast for Apr 21-Apr 23 2024 Apr 21 Apr 22 Apr 23 R1-R2 55% 55% 55% R3 or greater 15% 15% 15% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a slight chance for R3 (Strong) or greater events, over 21-23 Apr due to the flare potential of several active regions on the visible disk. ####018002449#### FXXX12 KWNP 211233 DAYDIS :Product: Forecast Discussion :Issued: 2024 Apr 21 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 # # Forecast Discussion # Solar Activity .24 hr Summary... Solar activity was low with C-class flare activity observed from several sources. The largest event was a C7.5 flare at 20/1706 UTC from Region 3645 (S09W26, Dki/beta-gamma). Slight growth was noted in Regions 3639 (N29W22, Eki/beta-gamma) and 3645, and new Region 3652 (N15E38, Bxo/beta) was numbered. The remaining regions were stable or in decay. No Earth-directed CMEs were detected in available coronagraph imagery. .Forecast... Solar activity is expected to be low over 21-23 Apr, with isolated M-class flares (R1-R2/Minor-Moderate) likely, and a slight chance for an X-class flare (R3/Strong). Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at normal to moderate levels and the greater than 10 MeV proton flux was steady at background levels. .Forecast... The greater than 2 MeV electron flux is expected to continue at normal to moderate levels over 21-23 Apr. There is a slight chance for the greater than 10 MeV proton flux to exceed S1 (Minor) storm levels over 21-23 Apr due to the flare potential of several active regions on the visible disk. Solar Wind .24 hr Summary... Solar wind conditions were nominal throughout the period. Wind speeds ranged between around 425-475 km/s, and trended slowly upward as the period progressed. Total magnetic field strength was between 2-6 nT and the Bz component varied +3/-6 nT. The phi angle was variable. .Forecast... Enhanced solar wind conditions are expected to prevail over 21-23 Apr due to CME activity (on 21 Apr) and negative polarity CH HSS influences (on 21-23 Apr). Geospace .24 hr Summary... The geomagnetic field was quiet and unsettled this period. .Forecast... Geomagnetic field activity is expected to be at unsettled to active levels on 21 Apr quiet due to CH HSS influences and the anticipated arrival of multiple CMEs from 16-18 Apr. Quiet and unsettled conditions are expected on 22 Apr, increasing to unsettled and active levels on 23 Apr with negative polarity CH HSS influences.