####018002434#### FXXX12 KWNP 281231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Sep 28 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 high levels. Region 4232 (N04E48, Dso/beta) produced an impulsive M6.4/1b flare (R2-Moderate) at 28/0843 UTC, the strongest of the period. Subsequent coronagraph imagery contained a CME signature towards the east. Analysis and modelling of the event is ongoing. The remaining nine active regions were either quiet or only produced C-class activity during the past 24 hours. .Forecast... Solar activity is likely to be moderate (R1-R2/Minor-Moderate) over 28-30 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux reached high levels with a peak of 1,723 pfu at 27/1655 UTC. The greater than 10 MeV proton flux was at background. .Forecast... The greater than 2 MeV electron flux is expected to continue at moderate to high levels over 28-30 Sep as CH HSS influences continue. 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 the onset of influence from an anticipated negative polarity CH HSS. Total magnetic field strength increased to a peak of 11 nT. The Bz component briefly reached as far south as -7 nT but rotated primarily northward after 28/0100 UTC. Solar wind speeds increased from ~350 km/s to ~425 km/s. Phi angle was predominantly oriented in the negative solar sector. .Forecast... Continued enhancements in the solar wind environment are likely on 28 Sep as influence from a negative polarity CH HSS persists. These enhancements are expected to continue through most of 29 Sep and into 30 Sep as CH HSS effects slowly wane. Geospace .24 hr Summary... The geomagnetic field was quiet to unsettled levels. .Forecast... Unsettled to active levels are expected, with a chance for isolated G1 (Minor) conditions, on 28 Sep due to influence from a negative polarity CH HSS. Quiet to unsettled levels are expected to return by the end of 29 Sep and into 30 Sep as CH HSS influence gradually diminishes. ####018002030#### FXXX10 KWNP 281231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Sep 28 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 Sep 28-Sep 30 2025 is 3.67 (below NOAA Scale levels). NOAA Kp index breakdown Sep 28-Sep 30 2025 Sep 28 Sep 29 Sep 30 00-03UT 3.00 3.33 2.67 03-06UT 3.00 3.67 2.33 06-09UT 1.33 3.00 2.00 09-12UT 2.00 3.00 2.00 12-15UT 3.33 2.67 2.00 15-18UT 3.67 2.67 2.00 18-21UT 3.00 2.00 2.00 21-00UT 3.00 2.00 2.00 Rationale: No G1 (Minor) or greater geomagnetic storms are expected. 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 28-Sep 30 2025 Sep 28 Sep 29 Sep 30 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 No radio blackouts were observed over the past 24 hours. Radio Blackout Forecast for Sep 28-Sep 30 2025 Sep 28 Sep 29 Sep 30 R1-R2 55% 55% 55% R3 or greater 5% 5% 5% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely over 28-30 Sep