:Issued: 2026 Jan 20 1247 UTC :Product: documentation at http://www.sidc.be/products/meu #--------------------------------------------------------------------# # DAILY BULLETIN ON SOLAR AND GEOMAGNETIC ACTIVITY from the SIDC # # (RWC Belgium) # #--------------------------------------------------------------------# SIDC URSIGRAM 60120 SIDC SOLAR BULLETIN 20 Jan 2026, 1246UT SIDC FORECAST SOLAR FLARES : M-class flares expected (probability >=50%) GEOMAGNETISM : Major (ISES: Severe) magstorm expected (A>=100 or K>=7) SOLAR PROTONS : Proton event in progress (>10 MeV) PREDICTIONS FOR 20 Jan 2026 10CM FLUX: 176 / AP: 060 PREDICTIONS FOR 21 Jan 2026 10CM FLUX: 176 / AP: 012 PREDICTIONS FOR 22 Jan 2026 10CM FLUX: 176 / AP: 007 Solar Active Regions and flaring: Solar flaring activity was somewhat low over the past 24 hours, with only C-class flares identified. The largest flare was a C8.0 flare (SIDC Flare 6695) peaking on January 19 at 19:21 UTC, produced by SIDC Sunspot Group 740 (NOAA Active Region 4341). SIDC Sunspot Group 740 is now located at S10W00 with a Beta-Gamma magnetic configuration and was stable over the past 24 hours. SIDC Sunspot Group 766 (NOAA Active Region 4345) grew over the past 24 hours and has a Beta-Gamma- Delta magnetic configuration. This region was the most active over the past 24 hours and produced most of the C-class flares. Solar flaring activity is expected to be moderate over the next 24 hours, with C-class flares expected and M-class flares likely. Coronal mass ejections: No Earth-directed coronal mass ejections (CMEs) were observed in SOHO/LASCO images over the past 24 hours. Due to contamination from the ongoing particle event, the CACTus tool automatically reported several halo CMEs between 2026 Jan 19 11:48 UTC and 15:36 UTC; these detections are false alerts. Coronal holes: SIDC Coronal Hole 146, a large trans-equatorial coronal hole with positive polarity, continues to cross the central meridian. Solar wind: The interplanetary CME (ICME) associated with the full-halo CME observed in SOHO/LASCO C2 on 2026 Jan 18 at 18:12 UTC (linked to the X1.9 flare, SIDC Flare 6678, peaking at 18:09 UTC from SIDC Sunspot Group 740, NOAA AR 4341, and accompanied by Type II radio emission) arrived at Earth significantly earlier than anticipated. The shock arrival is best timed from the jump in the interplanetary magnetic field (IMF), observed around 19:00 UTC by ACE and consistent with DSCOVR magnetic field data. Plasma measurements, including solar wind speed, were strongly disturbed by the ongoing solar energetic particle (SEP) event, so the early speed values are not reliable until around 21:14 UTC. After the shock, the north-south IMF component, Bz, gradually turned strongly southward, reaching about -58 nT at 21:04 UTC, before rapidly rotating northward to around +50 nT and remaining predominantly positive for several hours. Once the plasma data recovered, the ICME speed near Earth was around 1100 km/s, implying a Sun to Earth transit time of roughly 25 hours. Current observations indicate that solar wind speeds remain elevated near 900 km/s to 1000 km/s, while the total IMF has decreased to around 12 nT. Bz turned southward again around 05:30 UTC, reaching about -20 nT. Elevated solar wind speeds are expected to persist through the next day while the ICME continues to pass, after which conditions should gradually return toward a slower, more typical solar wind regime. Geomagnetism: Over the past 24 hours, geomagnetic conditions escalated from quiet to severe storm levels following the arrival of an interplanetary shock and a strong southward turning of the interplanetary magnetic field (IMF). The main driver was the north-south IMF component, Bz, which turned negative and reached strongly southward values, enabling efficient coupling between the solar wind and Earth’s magnetosphere and triggering a rapid intensification of geomagnetic activity. Locally, the Belgian K index (K_BEL) started to increase around 19:00 UTC, reached 8 by 21:00 UTC, and peaked at 9 at 22:00 UTC, indicating an extremely severe storm interval. Globally, the NOAA Kp index reached 8 for the 18:00 to 21:00 UTC three-hour interval and increased further to 9- for 21:00 to 24:00 UTC, consistent with a severe geomagnetic storm driven by the CME impact and its strongly southward magnetic field. Geomagnetic conditions again reached severe storm levels globally (NOAA Kp = 8-) between 06:00 and 09:00 UTC on January 20, following a prolonged period of negative Bz. Locally, moderate storm conditions were observed over Belgium (K_BEL = 6). With solar wind speeds still high, around 950 km/s, further major to severe storm intervals remain possible while Earth continues to be influenced by the ICME. Proton flux levels: The solar energetic particle event associated with the X1.9 flare (SIDC Flare 6678, peaking on 2026 Jan 18 at 18:09 UTC) is still ongoing. The greater than 10 MeV GOES proton flux has been above the 10 pfu threshold since 2026 Jan 18 at 22:50 UTC and remains above it. The greater than 10 MeV GOES proton flux is expected to remain elevated over the next 24 hours. Electron fluxes at GEO: The greater than 2 MeV electron flux remained slightly above the 1000 pfu alert threshold until 2026 Jan 19 at 08:00 UTC, in response to the high-speed solar wind stream. It then fell below the threshold. With the solar wind speed still elevated, the greater than 2 MeV electron flux is expected to increase again and may cross the threshold once the geomagnetic storm begins to subside. The 24-hour electron fluence was at moderate levels and is expected to decrease but remain at moderate levels. TODAY'S ESTIMATED ISN : 176, BASED ON 12 STATIONS. SOLAR INDICES FOR 19 Jan 2026 WOLF NUMBER CATANIA : /// 10CM SOLAR FLUX : 173 AK CHAMBON LA FORET : 109 AK WINGST : 087 ESTIMATED AP : 103 ESTIMATED ISN : 168, BASED ON 17 STATIONS. NOTICEABLE EVENTS SUMMARY DAY BEGIN MAX END LOC XRAY OP 10CM Catania/NOAA RADIO_BURST_TYPES 19 1109 1119 1122 ////// M1.1 ///4345 END BT #--------------------------------------------------------------------# # Solar Influences Data analysis Center - RWC Belgium # # Royal Observatory of Belgium # # # # Website http://www.sidc.be. # # E-mail sidc-support@oma.be # # To unsubscribe http://www.sidc.be/registration/unsub.php # # # # Legal notices: # # - Intellectual Property Rights: # # http://www.astro.oma.be/common/internet/en/data-policy-en.pdf # # - Liability Disclaimer: # # http://www.astro.oma.be/common/internet/en/disclaimer-en.pdf # # - Use and processing of your personal information: # # http://www.astro.oma.be/common/internet/en/privacy-policy-en.pdf # #--------------------------------------------------------------------#