####018002117#### FXXX10 KWNP 111231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Oct 11 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 5 (NOAA Scale G1). The greatest expected 3 hr Kp for Oct 11-Oct 13 2025 is 5.00 (NOAA Scale G1). NOAA Kp index breakdown Oct 11-Oct 13 2025 Oct 11 Oct 12 Oct 13 00-03UT 2.33 3.00 3.67 03-06UT 3.67 3.00 3.00 06-09UT 4.67 (G1) 3.67 3.00 09-12UT 3.00 4.67 (G1) 4.67 (G1) 12-15UT 4.00 3.00 3.00 15-18UT 3.67 3.67 2.00 18-21UT 3.67 5.00 (G1) 2.67 21-00UT 4.00 3.67 3.67 Rationale: Periods of G1 (Minor) geomagnetic storms are likely on 11-13 Oct in response to negative polarity CH HSS influences. 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 11-Oct 13 2025 Oct 11 Oct 12 Oct 13 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 Oct 11-Oct 13 2025 Oct 11 Oct 12 Oct 13 R1-R2 10% 10% 10% R3 or greater 1% 1% 1% Rationale: No R1 (Minor) or greater radio blackouts are expected. No significant active region flare activity is forecast. ####018002394#### FXXX12 KWNP 111231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Oct 11 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 declined to low levels with weak C-class flare activity observed from Regions 4245 (S10W87, Bxo/beta), 4246 (N22E04, Cso/beta) and 4248 (N07E40, Dso/beta-gamma). Region 4248 grew and developed a mixed polarity in the leader section. The remaining regions were little changed. No Earth-directed CMEs were observed in available coronagraph imagery. - .Forecast... There exists a slight chance for R1-R2 (Minor-Moderate) events over the next three days (11-13 Oct). Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux continued to reach high levels with a maximum flux of 2,513 pfu observed at 10/1825 UTC. The greater than 10 MeV proton flux continued at background levels. .Forecast... The greater than 2 MeV electron flux is expected to continue to reach high levels over 11-13 Oct. The greater than 10 MeV proton flux is expected to remain at background levels. Solar Wind .24 hr Summary... Solar wind conditions were indicative of a mildly enhanced IMF through about 11/0700 UTC. Total magnetic field strength hovered near 10 nT while the Bz component was mainly neutral to southward directed. Solar wind speed ranged primarily from 300-350 km/s and the phi angle was predominantly positive. After 11/0700 UTC, total magnetic field strength increased to 13 nT, while solar wind speed increased to near 450 km/s. Phi angle switched to a more negative orientation after 10/2330 UTC. .Forecast... Solar wind parameters are expected to remain enhanced in total magnetic field strength and solar wind speed late on 11 Oct through 13 Oct due to the onset of a recurrent, negative polarity coronal hole. Geospace .24 hr Summary... The geomagnetic field was quiet to minor storm (G1-Minor) levels in varied response to the mildly enhanced IMF. .Forecast... The geomagnetic field is likely to reach active to G1 (Minor) storm levels over 11-13 Oct due to the onset a recurrent, negative polarity CH HSS.