SIDC Ursigram

:Issued: 2024 Apr 18 1232 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 40418
SIDC SOLAR BULLETIN 18 Apr 2024, 1230UT
SIDC FORECAST 
SOLAR FLARES  : M-class flares expected (probability >=50%)
GEOMAGNETISM  : Quiet (A<20 and K<4)
SOLAR PROTONS : Quiet
PREDICTIONS FOR 18 Apr 2024  10CM FLUX: 224 / AP: 006
PREDICTIONS FOR 19 Apr 2024  10CM FLUX: 228 / AP: 017
PREDICTIONS FOR 20 Apr 2024  10CM FLUX: 224 / AP: 024

Solar Active Regions and flaring: Solar flaring activity was at moderate
level, with multiple C-class flares and three M-class flares recorded in
the past 24 hours. The largest flare of the period was an M2.2 flare,
peaking at 02:32 UTC on Apr 18, associated with NOAA AR 3643 (beta class).
This region also produced two further M-class flares (M1.6 and M1.3 peaking
at 22:08 UTC on Apr 17 and 07:37 UTC on Apr 18, respectively). NOAA AR 3639
is currently the largest and most complex region on disk (Beta-Gamma-
Delta), but produced only low level C-class flares. Low flaring activity
was also produced by NOAA AR 3638 (beta class) and NOAA AR 3645 (beta-gamma
class). NOAA AR 3633 and NOAA AR 3634 are expected to rotate over the west
limb in the next day. Other regions on the disc have simple configuration
of their photospheric magnetic field (alpha and beta) and did not show any
significant flaring activity. The solar flaring activity is expected to be
at moderate levels over the next 24 hours, with M-class flares possible and
a chance for X-class flare.

Coronal mass ejections: A small filament eruption occurred in the
southeastern quadrant from around 18:36 UTC on Apr 16, the associated
coronal mass ejection (CME) appears narrow and slow and is not expected to
arrive to Earth. Another filament eruption was observed in the northern
quadrant, first seen in SDO/AIA 304 at around 01:16 UTC on Apr 17. An
associated CME can be seen in SOHO/LASCO-C2 from 02:36 on Apr 17. The CME
is judged to be too narrow to reach Earth.
Multiple CMEs, directed towards south-east from the Earth's perspective,
were observed in SOHO/LASCO-C2 starting from approximately 17:16 on Apr 17,
likely related to the flaring activity from NOAA AR 3638 and 3643. Further
analysis is on-going to investigate if these CMEs have Earth directed
components. No other Earth-directed CMEs have been detected
in the available coronagraph imagery over the past 24 hours.



Coronal holes: A small negative polarity equatorial coronal hole has
transited the central meridian today, on Apr 18.

Solar wind: Over the past 24 hours, the solar wind parameters reflected the
waning influence of the ICME. The total magnetic field decreased from 10 nT
to the values around 6 nT. The solar wind speed ranged between 360 km/s and
410 km/s. The southward component of the interplanetary magnetic field
fluctuated between -7 nT and 8 nT. The interplanetary magnetic field phi
angle varied between being directed towards the Sun to being directed away
from the Sun. The solar wind conditions are expected to continue its return
to the slow solar wind regime in the next 24 hours with a chance for weak
enhancement on Apr 18 due to anticipated arrival of CME from Apr 15. On Apr
20 solar wind parameters might become slightly elevated due to the arrival
of a high-speed stream from a negative polarity coronal hole, that started
to cross the central meridian on Apr 17.


Geomagnetism: Geomagnetic conditions were quiet both globally and locally
(NOAA-Kp and K-BEL: 1 to 2) during the last 24 hours. Geomagnetic
conditions are expected to remain mostly at quiet to unsettled levels, with
a chance of reaching active levels on Apr 18 due to possible CME arrival.

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 with
possible enhancements in case of increased levels of solar activity over
the next days.

Electron fluxes at GEO: The greater than 2 MeV electron flux, as measured
by the GOES-16 satellite, remained below the 1000 pfu threshold. It is
expected to remain below the threshold during the next 24 hours. The 24
hour electron fluence was at normal levels and is expected to remain at
these levels for the following 24 hours.


TODAY'S ESTIMATED ISN  : 217, BASED ON 18 STATIONS.

SOLAR INDICES FOR 17 Apr 2024
WOLF NUMBER CATANIA    : 251
10CM SOLAR FLUX        : 217
AK CHAMBON LA FORET    : 008
AK WINGST              : 006
ESTIMATED AP           : 006
ESTIMATED ISN          : 208, BASED ON 25 STATIONS.

NOTICEABLE EVENTS SUMMARY
DAY BEGIN MAX  END  LOC    XRAY OP  10CM Catania/NOAA RADIO_BURST_TYPES 
17  2155  2208 2217 S07E22 M1.6 2N       62/3643      
18  0232  0248 0253 S11E27 M2.2 SF       62/3643      V/3 
18  0717  0737 0809 S12E23 M1.3 SF       62/3643      
END

BT
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