####018002117#### FXXX10 KWNP 181231 DAYTDF :Product: 3-Day Forecast :Issued: 2024 Apr 18 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 2 (below NOAA Scale levels). The greatest expected 3 hr Kp for Apr 18-Apr 20 2024 is 5.00 (NOAA Scale G1). NOAA Kp index breakdown Apr 18-Apr 20 2024 Apr 18 Apr 19 Apr 20 00-03UT 1.67 3.00 2.67 03-06UT 0.67 3.00 2.00 06-09UT 0.33 2.67 2.00 09-12UT 1.00 2.33 2.33 12-15UT 2.67 2.00 2.67 15-18UT 4.00 2.00 3.00 18-21UT 5.00 (G1) 2.00 2.67 21-00UT 3.33 2.00 2.33 Rationale: An isolated G1 (Minor) storm period is likely on 18 Apr due to the anticipated arrival of a CME from 15 Apr. 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 18-Apr 20 2024 Apr 18 Apr 19 Apr 20 S1 or greater 20% 20% 20% Rationale: There is a slight chance for S1 (Minor) solar radiation storms over 18-20 Apr. C. NOAA Radio Blackout Activity and Forecast Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Apr 18 2024 0248 UTC. Radio Blackout Forecast for Apr 18-Apr 20 2024 Apr 18 Apr 19 Apr 20 R1-R2 75% 75% 75% R3 or greater 20% 20% 20% Rationale: R1-R2 (Minor-Moderate) radio blackouts are expected, with a slight chance for R3 (Strong) or greater events, over 18-20 Apr. ####018002666#### FXXX12 KWNP 181231 DAYDIS :Product: Forecast Discussion :Issued: 2024 Apr 18 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 reached moderate levels. Region 3643 (S12E27, Fki/beta-gamma) produced three R1 (Minor) events, the largest of which was an M2.2/Sf flare at 18/0248 UTC. Regions 3643 and 3645 (S09E17, Dai/beta-gamma) exhibited moderate development this period with marked increases in total size and spot count. The remaining regions were either stable or in decay. Multiple CMEs were observed off the SE following a series of eruptions from the vicinity of Region 3638 (S18E14, Cri/beta) after 17/1730 UTC. Analysis suggests these CMEs are near misses directed to the East of the Sun-Earth line. No Earth-directed CMEs were detected in available satellite imagery. .Forecast... Solar activity is expected to reach moderate levels over 18-20 Apr with M-class flares (R1-R2/Minor-Moderate) likely, and a slight chance for X-class (R3/Strong) flares. 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 at background levels. .Forecast... The greater than 2 MeV electron flux is expected to be at normal to moderate levels over 18-20 Apr. There is a slight chance for the greater than 10 MeV proton flux to reach S1 (Minor) levels over 18-20 Apr. Solar Wind .24 hr Summary... A weakly enhanced solar wind environment prevailed throughout the period. Total field strength ranged 1-10 nT and Bz varied +9/-8 nT. Solar wind speeds increased from 350 km/s to a peak of 415 km/s, before gradually returning to around 350 km/s by the end of the period. .Forecast... Enhanced solar wind conditions are likely on 18 Apr due to the anticipated arrival of a CME from 15 Apr. Weakly enhanced conditions are likely on 19 Apr as CME influences wane, and again on 20 Apr due to the onset of negative polarity CH HSS influences. Geospace .24 hr Summary... The geomagnetic field was quiet. .Forecast... Active conditions and periods of G1 (Minor) storming are likely on 18 Apr due the anticipated arrival of a CME from 15 Apr. Quiet to unsettled conditions are expected on 19 Apr following CME passage. Quiet to unsettled levels are expected again on 20 Apr due to the onset of negative polarity CH HSS influences.