####018002128#### FXXX10 KWNP 191231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Oct 19 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 6 (NOAA Scale G2). The greatest expected 3 hr Kp for Oct 19-Oct 21 2025 is 5.00 (NOAA Scale G1). NOAA Kp index breakdown Oct 19-Oct 21 2025 Oct 19 Oct 20 Oct 21 00-03UT 5.00 (G1) 2.67 2.67 03-06UT 3.33 3.67 3.00 06-09UT 2.00 2.67 2.67 09-12UT 2.67 2.67 2.67 12-15UT 3.33 3.00 1.67 15-18UT 3.00 1.67 1.67 18-21UT 3.00 2.00 1.67 21-00UT 3.00 2.67 2.67 Rationale: No G1 (Minor) or greater geomagnetic storms are expected for the remainder of 19 Oct through 21 Oct. 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 Oct 19-Oct 21 2025 Oct 19 Oct 20 Oct 21 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 Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Oct 19 2025 0156 UTC. Radio Blackout Forecast for Oct 19-Oct 21 2025 Oct 19 Oct 20 Oct 21 R1-R2 50% 35% 35% R3 or greater 5% 5% 5% Rationale: There is a chance for R1-R2 (Minor-Moderate) radio blackouts over 19-21 Oct. ####018002448#### FXXX12 KWNP 191231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Oct 19 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 4246 (N25, L=288) produced most of the periods flare activity from beyond the west limb, including an M1.0 flare (R1-Minor) at 19/0156 UTC. Minor decay was observed in the trailing spots of Regions 4252 (S13W21, Cso/beta) and 4256 (S15E33, Cao/beta), while the remaining regions were stable. No Earth-directed CMEs were observed in available coronagraph imagery. .Forecast... Solar activity is expected to remain low, with a chance for isolated M-class flares (R1-R2/Minor-Moderate), over 19-21 Oct. 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 remained at background levels throughout the period. .Forecast... The greater than 2 MeV electron flux is expected to continue at normal to moderate levels on 19 Oct, and increase to high levels on 20-21 Oct. The greater than 10 MeV proton flux is expected to remain at background levels through 21 Oct. Solar Wind .24 hr Summary... Solar wind parameters were enhanced throughout the period due to a combination of CME influences followed by the onset of negative polarity CH HSS influences late in the period. Total magnetic field strength reached 15 nT, while the Bz component was sustained southward by as much as -12 nT between 18/1530-2015 UTC. Solar wind speeds ranged between 400-580 km/s. The phi angle was variable throughout the period. .Forecast... Enhanced solar wind conditions and negative polarity CH HSS influences are expected to prevail through 21 Oct. Geospace .24 hr Summary... The geomagnetic field reached G1-G2 (Minor-Moderate) storm levels during the period in response to CME and negative polarity CH HSS influences. .Forecast... Periods of active conditions are likely over 19-20 Oct, with a chance for G1 (Minor) storms on 19 Oct, due to negative polarity CH HSS influences. Quiet to unsettled conditions are likely to prevail on 21 Oct as CH HSS influences wanes.