SIDC Ursigram

:Issued: 2025 Dec 13 1231 UTC
:Product: documentation at http://www.sidc.be/products/meu
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# DAILY BULLETIN ON SOLAR AND GEOMAGNETIC ACTIVITY from the SIDC     #
# (RWC Belgium)                                                      #
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SIDC URSIGRAM 51213
SIDC SOLAR BULLETIN 13 Dec 2025, 1230UT
SIDC FORECAST 
SOLAR FLARES  : C-class flares expected, (probability >=50%)
GEOMAGNETISM  : Minor storm expected (A>=30 or K=5)
SOLAR PROTONS : Quiet
PREDICTIONS FOR 13 Dec 2025  10CM FLUX: 127 / AP: 034
PREDICTIONS FOR 14 Dec 2025  10CM FLUX: 125 / AP: 011
PREDICTIONS FOR 15 Dec 2025  10CM FLUX: 123 / AP: 010

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 C3.5
flare (SIDC Flare 6409) peaking at 15:58 UTC on December 12. It was
associated with SIDC Sunspot Group 712 (NOAA Active Region 4294), which has
since rotated across the west limb. There are currently six numbered active
regions on the solar disk. SIDC Sunspot Groups 722, 723 (NOAA Active
Regions 4307, 4308) are the most complex Groups, with magnetic type beta-
gamma. SIDC Sunspot Group 724 (magnetic type alpha) has emerged near the
center of the disk. SIDC Sunspot Groups 687 (NOAA Active Region 4299) has
decayed into a plage. The solar flaring activity is expected to be low over
the next 24 hours, with C-class flares very likely and a chance for M-class
flares.

Coronal mass ejections: A prominence eruption was observed in AIA 304 data
around 00:30 UTC on December 12, at the southeast limb. An associated slow,
wide CME (SIDC CME 609) was observed in LASCO/C2 coronagraph imagery
starting around 04:00 UTC on December 12, lifting off from the southeast
limb. It is not expected to impact Earth. No other Earth-directed CMEs were
observed in the available coronagraph imagery.

Solar wind: Over the past 24 hours, solar wind parameters (ACE) were
enhanced, most likely due to the influence of the high-speed stream from
the negative polarity coronal hole (SIDC Coronal Hole 142) and the ongoing
influence of an ICME arrival. Speed values increased from around 400 km/s
to around 600 km/s. The interplanetary magnetic field values varied between
6 nT and 16 nT. The Bz component varied between -14 nT and 15 nT. The
interplanetary magnetic field angle was mostly in the negative sector.
Enhanced solar wind conditions are expected to persist over the next 24
hours due to the continued influence of the high-speed stream.

Geomagnetism: Geomagnetic conditions globally were mostly at quiet to
unsettled levels (NOAA Kp 2 to 3), with an interval of minor storm
conditions (NOAA Kp 5) between 18:00 UTC on December 12 and 03:00 UTC on
December 13. Locally, geomagnetic conditions were mostly at quiet to active
levels (K BEL 2 to 4), with an interval of minor storm conditions (K BEL 5)
between 18:00 UTC and 20:00 UTC on December 12. Further minor to moderate
geomagnetic storm conditions remain possible over the next 24 hours due to
the continued influence of the high-speed stream.

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  : 085, BASED ON 06 STATIONS.

SOLAR INDICES FOR 12 Dec 2025
WOLF NUMBER CATANIA    : 144
10CM SOLAR FLUX        : 135
AK CHAMBON LA FORET    : 044
AK WINGST              : 033
ESTIMATED AP           : 032
ESTIMATED ISN          : 096, BASED ON 13 STATIONS.

NOTICEABLE EVENTS SUMMARY
DAY BEGIN MAX  END  LOC    XRAY OP  10CM Catania/NOAA RADIO_BURST_TYPES 
NONE
END

BT
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