Routine Space Environment Product (Daily)
Issued by NWS
Issued by NWS
365 FXXX12 KWNP 111231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Dec 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 reached moderate level due to multiple low level (R1-Minor) M-class flares, which all originated from Region 4294 (S15W81, Ekc/beta-gamma). Persistent flux emergence in its leading spot has supported its flare activity over the last two days. Regions 4304 (N26W49, Cai/beta-gamma) and 4305 (S25E06, Dao/beta) continued to show slight growth. All other regions were either stable or in decay. Two new regions rapidly developed and were numbered this period: 4306 (S16W28, Bxi/beta) and 4307 (S11E08, Bxo/beta). Region 4294 was responsible for the largest flare of the period, an M4.4/2B at 10/2208, that was also associated with a 520 sfu Tenflare, a Type-II radio burst (estimated velocity of 849 km/s) and an eruption observed at the SUVI 284A channel. An associated CME became visible in coronagraph imagery at 10/2224 UTC. Analysis suggests the bulk of the ejecta to pass ahead of Earths orbit. .Forecast... R1-R2 (Minor-Moderate) flare activity is expected (75% chance), with a slight chance (15%) for R3 (Strong) activity on 11 Dec. Probabilities remain elevated due to the complexity and history of the large complex of two regions in the south, decreasing as they pass beyond the western limb over 12-13 Dec. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux at geosynchronous orbit reached high levels, with a maximum of 2183 pfu at 10/1735 UTC. The greater than 10 MeV proton flux remained at background. .Forecast... Without the geoeffective positioning of any coronal hole high speed stream until 13 Dec, electrons will likely trend towards moderate levels through 12 Dec. Due the growth of Region 4294 and its favorable positioning in the west, there remains a slight chance (10%) for an S1 (Minor) radiation storming event on 12 Dec with decreasing chances as it moves beyond the limb. Solar Wind .24 hr Summary... Solar wind parameters have been enhanced throughout much of the period, due to a significant magnetic transient arrival between 10/1800-2100 UTC causing the total interplanetary magnetic field (Bt) to steadily increase for several hours, reaching a maximum of 22 nT at 11/0713 UTC. The magnetic field components at L1 were indicative of slow, relatively smooth rotation, with the north-south component (Bz) remaining southward (negative) for several hours, reaching a maximum of -17 nT at 11/0059 UTC. Wind speeds showed a slight response to the transients arrival, increasing to ~450 km/s at 10/2035 UTC and slowly decreasing to 400 by the end of the reporting period. The phi angle was predominantly positive, indicating the heliospheric current sheet was largely oriented away from the Sun. Signatures in phi and density around the transients arrival could be indicative of a reverse shock. .Forecast... Solar wind parameters will likely remain enhanced throughout the rest of 11 Dec and likely into 12 Dec, as the decay in Bt has been quite slow. The co-rotating interacting region (CIR) ahead of the negative polarity coronal hole (CH) high speed stream (HSS) is also anticipated to arrive during this time period. Geospace .24 hr Summary... The geomagnetic field reached G2 (Moderate) geomagnetic storming levels due to the solar wind disturbance that arrived around 10/2000 UTC. .Forecast... A return to unsettled to active conditions is likely throughout the remainder of 11 Dec and into 12-13 Dec, with a small potential for isolated minor storming (G1) as the CIR arrives.