Routine Space Environment Product (Daily)
Issued by NWS
Issued by NWS
270 FXXX12 KWNP 151231 DAYDIS :Product: Forecast Discussion :Issued: 2025 Sep 15 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 low. Region 4217 (S17E63, Dao/beta) continued to be the main flare producer. This region added several C-class flares, including a C3.8 at 14/1518 UTC, the largest of the period. Additional trailer spots were noted as the region continued to rotate into view from the east limb. Region 4216 (N10E28, Dki/beta) developed additional intermediate and trailer spots and grew in overall areal coverage, but remained mostly inactive. Region 4218 (N14W80, Cao/beta) was mostly unchanged as it made its way towards the west limb. New Region 4219 (N26W08, Dao/beta) was numbered, but was also mostly quiet. No Earth-directed CMEs were noted this period. .Forecast... Solar activity is expected to be low, with a chance for an isolated M-flare (R1-R2/Minor-Moderate), through 17 Sep. Energetic Particle .24 hr Summary... The greater than 2 MeV electron flux reached high levels with a peak flux of 1,570 pfu observed at 14/2000 UTC. The greater than 10 MeV proton flux was steady at background levels. .Forecast... The greater than 2 MeV electron flux is expected to reach high levels on 15 Sep, before decreasing to normal to moderate levels on 16-17 Sep. The greater than 10 MeV proton flux is expected to persist at background levels through 17 Sep. Solar Wind .24 hr Summary... The solar wind parameters were indicative of a CIR arrival followed by the onset of a negative polarity CH HSS. Total field increased to a peak of 21 nT before declining back to average near 11 nT. The Bz component saw a maximum southward deflection to -17 nT but has since become variable between +12/-7 nT. Solar wind speeds peaked near 823 km/s and have remained elevated to near 600 km/s since. The phi angle began rotating from positive to negative after ~14/1800 UTC, moving solidly into a negative orientation after around 14/2130 UTC. .Forecast... The solar wind environment is expected to remain enhanced over 15-17 Sep due to negative polarity CH HSS influences. Further enhancements are possible on 15 Sep if the CME from 11 Sep passes in close proximity to Earth. Geospace .24 hr Summary... The geomagnetic field reached G3 (Strong) geomagnetic storm levels following the onset of the CIR/CH HSS. .Forecast... Periods of G1/G2 (Minor-Moderate) geomagnetic storming are expected through midday on 15 Sep due to negative polarity CH HSS influences, in addition to possible influence from the 11 Sep CME if it passes in close proximity to Earth. Active conditions are likely on 16 Sep, with a chance for G1 (Minor) storm periods early, under continued negative polarity CH HSS influences. Quiet to unsettled levels are expected on 17 Sep as CH HSS influences diminish.