SIDC Ursigram

:Issued: 2026 Jul 21 1242 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 60721
SIDC SOLAR BULLETIN 21 Jul 2026, 1241UT
SIDC FORECAST 
SOLAR FLARES  : C-class flares expected, (probability >=50%)
GEOMAGNETISM  : Minor storm expected (A>=30 or K=5)
SOLAR PROTONS : Quiet
PREDICTIONS FOR 21 Jul 2026  10CM FLUX: 144 / AP: 028
PREDICTIONS FOR 22 Jul 2026  10CM FLUX: 148 / AP: 022
PREDICTIONS FOR 23 Jul 2026  10CM FLUX: 152 / AP: 032

Solar Active Regions and flaring: Solar flaring activity was at moderate
levels over the past 24 hours with3 M-class flares identified. A total of 6
numbered sunspot groups were identified on the disk over the past 24 hours.
The largest flare was a M3.4 flare (SIDC Flare 8220) peaking on July 20 at
22:25 UTC, produced by SIDC Sunspot Group 920 (NOAA Active Region 4493).
This region, classified as magnetic type beta-gamma-delta represents the
largest and most complex sunspot group on the visible disk, responsible for
most of the observed flaring activity, including an M2.5 flare (SIDC Flare
8215) peaking on July 20 at 14:36 UTC and an M1.1 flare (SIDC Flare 8214)
peaking on July 20 at 19:20 UTC. SIDC Sunspot Group 919 (NOAA Active Region
4492) currently located at N15E55 is classified as magnetic type beta-
gamma, but has produced only isolated low levels of activity. The remaining
regions are magnetically simpler and have been quiet. The solar flaring
activity is expected to be at low to moderate levels over the next 24
hours with C-class flares expected and chances for further M-class
flaring.

Coronal mass ejections: No Earth-directed coronal mass ejections (CMEs)
have been identified in the available coronagraph imagery over the past 24
hours.

Coronal holes: SIDC Coronal Hole 149 (an equatorial coronal hole with a
negative polarity) which first reached the central meridian on July 19
continues to partially reside there. An associated high speed stream
arrival is about to arrive at the Earth in the upcoming hours.
SIDC Coronal Hole 142 (recurrent mid-to-equatorial latitude coronal hole
with a negative polarity) has crossed the central meridian on July 20 and
continues to reside there. A high speed-stream related to it could be
anticipated at Earth on July 23, most probably mixed with ongoing high
speed stream from SIDC 149.

Solar wind: Over the past 24 hours the solar wind parameters (as measured
by ACE at L1) have registered enhancements most probably precursors of an
expected high-speed stream arrival from SIDC Coronal Hole 149. The solar
wind speed has increased to 430 km/s. The interplanetary magnetic field (B)
was enhanced reaching a maximum magnitude of 17.23 nT with a minimum north-
south (Bz) component of - 12.2 nT. The B field phi angle has switched from
the positive sector to the negative sector (directed towards the Sun). The
solar wind parameters are expected to reflect high speed stream conditions
over the next days with an anticipated secondary high-speed stream arrival
on July 21 related to SIDC Coronal Hole 142.

Geomagnetism: The geomagnetic conditions over the past 24 hours have been
locally quiet to unsettled and globally have reached active levels as
measured by the NOAA Kp index between 09 and 12 UTC on July 21.
Predominantly unsettled to minor storm levels are expected over the next 24
hours with chances for isolated moderate storm conditions due to an ongoing
high-speed stream arrival related to SIDC coronal hole 149. Further minor
to moderate geomagnetic storm might be expected on July 23 with an
anticipated high speed stream arrival related to SIDC coronal hole 142.

Proton flux levels: Over the past 24 hours the greater than 10 MeV GOES
proton flux was at nominal levels and is expected to remain so over the 24
hours.

Electron fluxes at GEO: The greater than 2 MeV electron flux as measured by
GOES 18 and GOES 19 was slowly oscillating around the 1000 pfu threshold
over the past 24 hours. It is expected to be below the 1000 pfu threshold
over the 24 hours. The 24-hour electron fluence was at the border of
nominal to moderate levels and is expected to temporary decrease to nominal
levels over the 24 hours.


TODAY'S ESTIMATED ISN  : 094, BASED ON 24 STATIONS.

SOLAR INDICES FOR 20 Jul 2026
WOLF NUMBER CATANIA    : ///
10CM SOLAR FLUX        : 137
AK CHAMBON LA FORET    : 010
AK WINGST              : 006
ESTIMATED AP           : 004
ESTIMATED ISN          : 083, BASED ON 32 STATIONS.

NOTICEABLE EVENTS SUMMARY
DAY BEGIN MAX  END  LOC    XRAY OP  10CM Catania/NOAA RADIO_BURST_TYPES 
20  1429  1436 1440 ////// M2.5          ///4493      
20  1908  1920 1926 ////// M1.1          ///4493      VI/2 
20  2215  2225 2231 ////// M3.4          ///4493      
END

BT
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