####018002250#### FXXX10 KWNP 161231 DAYTDF :Product: 3-Day Forecast :Issued: 2025 Oct 16 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 2 (below NOAA Scale levels). The greatest expected 3 hr Kp for Oct 16-Oct 18 2025 is 5.67 (NOAA Scale G2). NOAA Kp index breakdown Oct 16-Oct 18 2025 Oct 16 Oct 17 Oct 18 00-03UT 1.00 5.00 (G1) 3.00 03-06UT 1.00 4.67 (G1) 2.00 06-09UT 1.67 3.67 2.00 09-12UT 2.67 3.67 2.67 12-15UT 2.67 3.67 2.67 15-18UT 3.33 3.33 2.67 18-21UT 5.33 (G1) 3.00 2.67 21-00UT 5.67 (G2) 2.67 3.00 Rationale: G1-G2 (Minor-Moderate) geomagnetic storm conditions are likely over 16-17 Oct due to the arrival of multiple CMEs from 11-13 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 16-Oct 18 2025 Oct 16 Oct 17 Oct 18 S1 or greater 10% 10% 10% Rationale: There is a slight chance for a greater than 10 MeV proton event above the S1 (Minor) levels through 18 Oct. 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 15 2025 2228 UTC. Radio Blackout Forecast for Oct 16-Oct 18 2025 Oct 16 Oct 17 Oct 18 R1-R2 60% 60% 60% R3 or greater 15% 15% 15% Rationale: Minor to moderate (R1-R2) radio blackouts are likely for the next 3 days, with a slight chance for an isolated R3 (Strong) event, due to the current and potential flare activity of Regions 4246 and 4248. ####018003829#### FXXX12 KWNP 161231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Oct 16 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 continued at moderate levels due to M-class flare activity from Region 4246 (N22W63, Ekc/beta-gamma-delta). Notable flares included a long duration M1.1 flare that peaked at 15/1410 UTC, another long duration M2.7 flare at 15/2228 UTC, and an M2.4 flare at 15/2345 UTC. The M1.1 flare had an associated Tenflare (peaking at 180 sfu at 15/1524 UTC) observed by SAG USAF RSTN radio stations, as well as two CMEs off the W and NW beginning at 15/1512 UTC. The M2.7 flare also had ejecta associated with it as seen in SUVI 195 imagery at 15/2200 UTC and LASCO C2 at 15/2236 UTC. Modeling efforts showed a combined possible glancing pass on 18 Oct. Further analysis is still ongoing at the time of this summary. Region 4246 also produced multiple C-class flares in the past 24h, as it grew and matured its intermediary spots. Region 4248 (N07W34, Eki/beta-gamma-delta) presented no significative change in size or magnetic complexity. Region 4250 (N07W28, Hrx/alpha) continued to decay and lost its trailing spot. Region 4252 (S13E35, Cao/beta) developed a little trailing spot as it rotated towards the center of the solar disk. Region 4254 (N10E60, Hsx/alpha) showed no significant change. Two new spotted regions appeared this period in the SE quadrant near S06E51 and S16E77, respectively. These two regions have yet to be assigned a number as we await further observations. .Forecast... Minor to moderate (R1-R2) radio blackouts are likely through 18 Oct, with a slight chance for an isolated R3 (Strong) event, due to the current and potential flare activity of Regions 4246 and 4248. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux reached high levels with a maximum flux of 2,850 pfu observed at 15/1540 UTC. The greater than 10 MeV proton flux remained at background levels during this period. .Forecast... The greater than 2 MeV electron flux is expected to decrease to normal to moderate levels on 16 Oct with the CME arrivals and rebound to moderate to high levels on 17-18 Oct. There is a slight chance for a greater than 10 MeV proton event above the S1 (Minor) levels through 18 Oct. Solar Wind .24 hr Summary... Solar Wind parameters were slowly returning to nominal levels as the effect of the negative CH HSS waned. Total interplanetary magnetic field remained at or below 6 nT level during the whole period, with the Bz component between +3/-4 nT. Phi angle was predominantly in the negative sector, as expected during the negative CH HSS influence. Solar wind speeds slowly decreased from about 520 km/s to 450 km/s. .Forecast... Solar wind parameters are expected to continue gradually waning over the course of 16 Oct as the influence of negative CH HSS reduces. Disturbed solar wind conditions are expected by late on 16 Oct, and continuing through 18 Oct, due to CME arrivals from 11-13, and 15 Oct originating from AR 4246. Geospace .24 hr Summary... Geomagnetic field activity was mostly quiet. .Forecast... Geomagnetic field activity will likely reach G2 (Moderate) storm levels late on 16 Oct in response to CMEs that left the Sun over the course of 11-13 Oct affecting the near-Earth environment. G1 (Minor) geomagnetic storm activity is then likely to carry over into 17-18 Oct with additional CME influences possible from the 15 Oct activity from AR 4246.