####018002545#### FXXX12 KWNP 291231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Sep 29 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 at low levels. Region 4232 (N05E42, Dso/beta-gamma) produced the largest event of the period, an impulsive M3.6 flare (R1-Minor) at 29/0145 UTC. An associated CME was observed in subsequent SOHO LASCO/C2 coronagraph imagery beginning at 29/0212 UTC. Analysis and modelling of the ejecta is ongoing. Newly numbered Region 4237 (N16E02, Bxo/beta) remained relatively quiet as it developed. Region 4263 (N11W33, Dai/beta-gamma) also produced an R1 event with an M1.0/Sf flare near the end of the reporting period at 26/1108 UTC. .Forecast... Solar activity is likely to be at moderate levels (R1-R2/Minor-Moderate) with a slight chance for an X-class flare (R3-Strong) over 29 Sep - 01 Oct. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux was at moderate levels. The greater than 10 MeV proton flux was at background. .Forecast... The greater than 2 MeV electron flux is expected to be at moderate levels over 29 Sep - 01 Oct. The greater than 10 MeV proton flux is expected to continue at background levels all three days. Solar Wind .24 hr Summary... Solar wind parameters suggested weak influence from a negative polarity CH HSS. Total magnetic field strength reached a peak of 15nT and persisted above 10 nT for most of the period. The Bz component rotated southward after 28/2000 UTC, reaching as far south as -13 nT. Solar wind speeds fluctuated in the range of ~375 km/s to ~450 km/s. Phi angle was oriented in the negative solar sector. .Forecast... Weak enhancements in the solar wind environment are likely to continue on 29 Sep as influence from a negative polarity CH HSS persists. Waning CH HSS influences are expected by 30 Sep into 01 Oct, with decreasing enhancements reflected in the solar wind parameters. Geospace .24 hr Summary... The geomagnetic field was quiet to active levels. .Forecast... Unsettled to isolated G1 (Minor) conditions are expected on 29 Sep due to influence from a negative polarity CH HSS. Mostly quiet levels are expected to return over 30 Sep and 01 Oct as CH HSS influence gradually declines. ####018002238#### FXXX10 KWNP 291231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Sep 29 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 4 (below NOAA Scale levels). The greatest expected 3 hr Kp for Sep 29-Oct 01 2025 is 3.67 (below NOAA Scale levels). NOAA Kp index breakdown Sep 29-Oct 01 2025 Sep 29 Sep 30 Oct 01 00-03UT 2.67 2.67 1.67 03-06UT 2.67 2.67 1.33 06-09UT 3.67 2.00 1.33 09-12UT 4.67 2.00 1.67 12-15UT 2.33 2.00 1.33 15-18UT 4.67 2.00 1.00 18-21UT 2.00 2.00 1.33 21-00UT 2.00 2.00 1.67 Rationale: G1 (Minor) geomagnetic storms are likely on 29 Sep due to coronal hole effects. 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 Sep 29-Oct 01 2025 Sep 29 Sep 30 Oct 01 S1 or greater 5% 5% 5% 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 Sep 29 2025 0145 UTC. Radio Blackout Forecast for Sep 29-Oct 01 2025 Sep 29 Sep 30 Oct 01 R1-R2 55% 55% 55% R3 or greater 10% 10% 10% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely, with a slight chance for R3 (Strong), over 29 Sep - 01 Oct due to the flare potential from multiple complex regions on the solar disk.