####018002136#### FXXX10 KWNP 301231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Sep 30 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 7 (NOAA Scale G3). The greatest expected 3 hr Kp for Sep 30-Oct 02 2025 is 7.33 (NOAA Scale G3). NOAA Kp index breakdown Sep 30-Oct 02 2025 Sep 30 Oct 01 Oct 02 00-03UT 5.33 (G1) 4.00 2.33 03-06UT 7.33 (G3) 3.67 2.00 06-09UT 6.00 (G2) 3.33 1.67 09-12UT 5.33 (G1) 3.00 1.67 12-15UT 5.00 (G1) 2.67 1.33 15-18UT 4.67 (G1) 2.67 1.33 18-21UT 5.00 (G1) 2.67 1.67 21-00UT 4.00 2.67 1.67 Rationale: G1 (Minor) geomagnetic storms are expected 30 Sep due to a CME/MC influence. 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 30-Oct 02 2025 Sep 30 Oct 01 Oct 02 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 30 2025 0940 UTC. Radio Blackout Forecast for Sep 30-Oct 02 2025 Sep 30 Oct 01 Oct 02 R1-R2 60% 60% 60% R3 or greater 15% 15% 15% Rationale: R1-R2 (Minor-Moderate) radio blackouts are likely with a slight chance for R3 (strong) event through 02 Oct. ####018003272#### FXXX12 KWNP 301231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Sep 30 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 moderate levels due to M-class flare activity. Region 4232 (N04E22, Dhi/beta-gamma) produced an M1.2 flare peaking at 30/0056UTC as it gained additional spots and grew in area. Region 4226 (S09W62, Hsx/alpha) produced an M2.7/1N at 30/0940UTC but was otherwise stable in size and magnetic complexity. Region 4230 (S11W37, Dai/beta-gamma-delta) became more complex magnetically as it doubled in area in the last 24h as its trailing penumbra matured. Region 4236 (N10E14, Dkc/beta-gamma-delta) grew in overall size, became more complex magnetically and compact. During the period, to new spots were observed, one of them was numbered 4240 (N16E67, Axx/alpha) and the other (located around N10W19) remained unnumbered as we observe its progress in the next period. A proeminence was observed at SUVI 304 erupting from the SW limb around 30/0840UT and became visible at LASCO C2 coronagraph image at 30/0936UTC. Modeling of this event will commence once substantial imagery becomes available, but an Earth-directed component seems unlikely at this time given the source location. .Forecast... With multiple regions continuing to exhibit growth, flare activity is likely to remain at moderate levels (R1-R2/Minor-Moderate) with a slight chance for an X-class flare (R3-Strong) through 02 Oct. Energetic Particle .24 hr Summary... The greater than 2 MeV electrons were at normal to moderate levels. The greater than 10 MeV proton flux remained at background levels. .Forecast... The greater than 2 MeV electrons are expected to remain at normal to moderate levels on 30 Sep with a chance for high levels 01-02 Oct due to magnetospheric response to CME influences. The greater than 10 MeV proton flux is expected to remain at background levels. Solar Wind .24 hr Summary... The solar wind environment was enhanced under likely CME or magnetic cloud (MC) influences. The total Interplanetary Magnetic Field reached 20nT, with a negative north-south Bz component of -15nT around 30/0600UTC. The solar wind speed gradually increased, crossing the 500 km/s level around 30/1210UTC. The Phi angle rotated between positive and negative sectors during the period. .Forecast... CME/MC influences are expected to persist for the remainder 30 Sep before gradually declining over the course of 01 Oct and return to nominal levels by 02 Oct. Geospace .24 hr Summary... The geomagnetic activity reached G3 (Strong) level during the 03-06 UTC synoptic period and was followed by a G2 (Moderate) level during the subsequent period (06-09 UTC). .Forecast... Active to G1 (Minor) geomagnetic storm is expected for the remainder 30 Sep. Unsettled to active conditions are expected on 01 Oct as CME/MC effects wane. Primarily quiet geomagnetic conditions are expected on 02 Oct.