SIDC Ursigram

:Issued: 2024 Apr 27 1250 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 40427
SIDC SOLAR BULLETIN 27 Apr 2024, 1249UT
SIDC FORECAST 
SOLAR FLARES  : M-class flares expected (probability >=50%)
GEOMAGNETISM  : Minor storm expected (A>=30 or K=5)
SOLAR PROTONS : Warning condition (activity levels expected to increase,
but no numeric forecast given)
PREDICTIONS FOR 27 Apr 2024  10CM FLUX: 155 / AP: 010
PREDICTIONS FOR 28 Apr 2024  10CM FLUX: 153 / AP: 023
PREDICTIONS FOR 29 Apr 2024  10CM FLUX: 152 / AP: 013

Solar Active Regions and flaring: Solar flaring activity was at low levels
over the past 24 hours with background C-class flaring. With several
regions rotating behind the west limb there are currently 11 numbered
active regions on the visible solar disc with NOAA AR 3654 (beta-gamma)
near disc centre being the largest and most complex region. A new regions
has fully rotated from the east limb, but remains silent. A few other small
and simple regions in the easter hemisphere also remain quiet and
unnumbered. The strongest activity was a C6.1 flare, peak time 20:22 UTC on
April 26th, possibly produced by NOAA AR 3648 (previously beta-gamma) from
the the west limb. The solar flaring activity is expected to be at low to
moderate levels over the next days with possible isolated M-class flaring
mainly from NOAA AR 3654 and less likely from NOAA AR 3648.

Coronal mass ejections: A large filament eruption was observed to lift off
the south-east hemisphere around 18:00 UTC on April 26th with resulting
slow coronal mass ejection (CME) and white light shock visible in the
LASCO/C2 coronagraph imagery. Current analysis suggests no Earth-directed
impact from this CME. No other Earth-directed CMEs have been observed in
the available coronagraph imagery over the past 24 hours.


Coronal holes: A long negative polarity coronal hole stretching from high
northern latitudes down to the equator is now touching the central
meridian. The high speed stream emanating from it might arrive to Earth on
May 1st.

Solar wind: Over the past 24 hours the solar wind parameters (ACE and
DSCOVR) were indicative of a mixture of a glancing blow ICME arrival,
possibly an early arrival of the April 24th CME, and an expected high speed
stream (HSS) arrival from a positive polarity coronal hole. A tiny slow
forward solar wind shock was observed around 00:00 UTC on April 27th. The
solar wind velocity was in the range of 305 to 546 km/s. The interplanetary
magnetic field (B) reached a maximum value of 16.8 nT with a minimum Bz of
-11.6 nT. The B field phi angle switched orientation from negative to the
positive sector (directed away from the Sun). The solar wind conditions are
expected to remain elevated throughout April 27th and April 28th and
possibly remain elevated throughout April 30th due to expected second HSS
stream arrival from another positive polarity coronal hole. Further arrival
of a HSS from a negative polarity coronal hole is possible on May 1st.

Geomagnetism: The geomagnetic conditions over the past 24 hours were at
quiet to minor storm levels. Quiet to active conditions with possible new
minor storm levels are anticipated for April 27th - April 29th.

Proton flux levels: Over the past 24 hours the greater than 10 MeV GOES
proton flux was at background levels and is expected to remain so over the
next days, pending any fast eruptive solar activity.


Electron fluxes at GEO: The greater than 2 MeV electron flux as measured by
GOES 16 and GOES 18 was below the1000 pfu threshold over the past 24 hours.
The greater than 2 MeV electron flux as measured by GOES 16 and GOES 18 is
expected to remain below the 1000 pfu threshold in the next 24 hours. The
24h electron fluence was at nominal levels and is expected to remain so
over the next 24 hours.


TODAY'S ESTIMATED ISN  : 147, BASED ON 13 STATIONS.

SOLAR INDICES FOR 26 Apr 2024
WOLF NUMBER CATANIA    : ///
10CM SOLAR FLUX        : 153
AK CHAMBON LA FORET    : 031
AK WINGST              : 023
ESTIMATED AP           : 021
ESTIMATED ISN          : 135, BASED ON 20 STATIONS.

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

BT
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