Summary and Forecast

Solar Summary

(last updated 13 Dec 2025 23:30 UT)

Activity 13 Dec: R0 Flares: none. Observed 10.7 cm flux/Equivalent Sunspot Number for 13 Dec: 122/75

Solar Forecast

(last updated 13 Dec 2025 23:30 UT)

14 Dec 15 Dec 16 Dec Activity R0 R0 R0 Fadeouts None expected None expected None expected 10.7cm/SSN 120/72 120/72 120/72 COMMENT: Solar activity was at the R0 level for UT day 13-Dec. No significant flares were observed with solar region AR4296 (S15W83, beta) producing the largest flare of the day a C8.6 at 13/1051UT. Region AR4296 is rotating off disk. There is currently no solar region of significant area on the visible solar disk. Solar regions AR4307 (S13W17, beta-gamma) and AR4308 (N11E46, beta) have shown minor growth. There are currently five regions on the visible solar disk. Other regions are stable or in decay. Plasma ejecta was observed on the southwest solar limb at solar latitude S20 from 13/1057UT in GOES 304 imagery. R0 conditions are forecast for 14-16 Dec. S0 solar radiation storm conditions were observed on 13-Dec. S0 solar radiation storm conditions are expected over 14-16 Dec. The western arm of a north polar extension coronal hole is now past the solar central meridian, with the longer eastern arm of the hole just to the east of the central meridian. No geoeffective coronal mass ejections were observed over the past UT day. A southwest directed CME was observed in LASCO C2 imagery from 13/1112UT in association with the plasma ejecta on the southwest solar limb and is expected to pass well ahead of the Earth. The solar wind speed increased to strong due to the influence from the arm of the coronal hole now west of the centre of the solar disk. The solar wind speed ranged between 472-689 km/s and is currently at 689 km/s. The peak total interplanetary magnetic field strength (IMF, Bt) was 17 nT and the north-south IMF component (Bz) range was -6 to 15 nT. The interplanetary magnetic field strength was enhanced up to 13/0900UT then dropped as the Earth entered the coronal wind stream and is now a very small magnitude of approximately 4 nT. The IMF Bz was mildly southward (-6 nT) early in the UT day then became orientated northwards. Coronal hole high speed wind stream effects are expected to sustain elevated wind speed conditions on 14-Dec, with the IMF expected to remain small in magnitude.

Solar Activity levels are explained in the SWS Solar Terrestrial Glossary.