:Issued: 2026 May 13 1231 UTC :Product: documentation at http://www.sidc.be/products/meu #--------------------------------------------------------------------# # DAILY BULLETIN ON SOLAR AND GEOMAGNETIC ACTIVITY from the SIDC # # (RWC Belgium) # #--------------------------------------------------------------------# SIDC URSIGRAM 60513 SIDC SOLAR BULLETIN 13 May 2026, 1230UT SIDC FORECAST SOLAR FLARES : M-class flares expected (probability >=50%) GEOMAGNETISM : Minor storm expected (A>=30 or K=5) SOLAR PROTONS : Quiet PREDICTIONS FOR 13 May 2026 10CM FLUX: 108 / AP: 027 PREDICTIONS FOR 14 May 2026 10CM FLUX: 105 / AP: 014 PREDICTIONS FOR 15 May 2026 10CM FLUX: 104 / AP: 019 Solar Active Regions and flaring: Solar flaring activity was low over the past 24 hours, with only C-class flares. The strongest flare was a C2.3 flare (SIDC Flare 7677), peaking at 06:40 UTC on May 13, which was associated with the returning SIDC Sunspot Group 825 (NOAA Active Region 4436, magnetic type beta). There are currently five numbered active regions on the solar disk. SIDC Sunspot Group 860 (NOAA Active Region 4432) is the most complex group with magnetic type beta-gamma and is currently rotating across the west limb. SIDC Sunspot Group 867 (magnetic type beta) has emerged in the northwest quadrant. The 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 the available coronagraph imagery in the last 24 hours. Coronal holes: A large, negative polarity, transequatorial coronal hole (returning SIDC Coronal Hole 147) has started to cross the central meridian. The associated high-speed stream is expected to arrive at Earth starting late on May 15. Solar wind: Over the past 24 hours, the solar wind parameters (ACE) initially reflected slow solar wind conditions, with an enhancement observed during the last hours of the period. Speed values ranged between 320 km/s and the current value of approximately 440 km/s. The interplanetary magnetic field values increased from 5 nT up to 13 nT. The Bz component varied between -7 nT and 13 nT. The interplanetary magnetic field angle was mostly in the positive sector until around 11:00 UTC on May 13, when it switched to the negative sector. The observed enhancement is most likely associated with the possible glancing blow arrival of the Coronal Mass Ejection (SIDC CME 650) observed at 13:48 UTC on May 10. The association will be further assessed as more data become available. Further enhancements in the solar wind parameters may be possible over the next 24 hours. Geomagnetism: Geomagnetic conditions globally were mostly at quiet levels (NOAA Kp 1 to 2). Locally, geomagnetic conditions were mostly quiet, reaching unsettled levels during the last hour of the period (K BEL 1 to 3). Active to minor storm conditions may be possible over the next 24 hours, due to the observed solar wind enhancement, most likely associated with the possible glancing blow arrival of the Coronal Mass Ejection (SIDC CME 650) observed at 13:48 UTC on May 10. Proton flux levels: The greater than 10 MeV proton flux was below the 10 pfu threshold level over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours. Electron fluxes at GEO: The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 was below the 1000 pfu threshold in the last 24 hours. The greater than 2 MeV electron flux is expected to be below the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence is presently at normal levels and is expected to remain so over the next 24 hours. TODAY'S ESTIMATED ISN : 070, BASED ON 16 STATIONS. SOLAR INDICES FOR 12 May 2026 WOLF NUMBER CATANIA : 066 10CM SOLAR FLUX : 111 AK CHAMBON LA FORET : 008 AK WINGST : 005 ESTIMATED AP : 003 ESTIMATED ISN : 059, BASED ON 23 STATIONS. NOTICEABLE EVENTS SUMMARY DAY BEGIN MAX END LOC XRAY OP 10CM Catania/NOAA RADIO_BURST_TYPES NONE 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 # #--------------------------------------------------------------------#