Viewing archive of Saturday, 29 May 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 May 29 1232 UTC

SIDC Forecast

Solar flares

C-class flares expected, (probability >=50%)

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
29 May 2021	076	012
30 May 2021	076	006
31 May 2021	075	004

Bulletin

Beta-gamma region NOAA 2824 has released four C flares during the past 24 hours. The brightest flare was a C9.4 flare peaking at 23:13 UT on May 28. This flare was associated with a dimming detected by Solar Demon and a CME towards the West first observed in LASCO C2 imagery at 23:12 UT. The chance for a C flare in the next 24 hours is estimated at 85%, while the chance for an M flare is estimated at 35%.

Analysis of LASCO C2 and COR2 A images suggests the CME mentioned above has a speed around 840 km/s and a half cone angle of about 50 degrees. There is a slight chance it will deliver a glancing blow to Earth, with estimated arrival time 13h UT on May 31.

A proton event started around 0h UT on May 29, related to the C9.4 flare and associated CME. The greater than 10 MeV proton flux reached a maximum of about 16 pfu around 03:20 UT. Proton flux levels went below the 10 pfu threshold around 05:50 UT and are decreasing further. The proton event is finished, but there is a chance for further proton events in the next 48 hours. The greater than 2 MeV electron flux was at nominal levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours. The greater than 2 MeV electron fluence was at nominal levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours.

The solar wind speed as registered by DSCOVR varied between about 365 km/s and 460 km/s in the past 24 hours, with current values around 425 km/s. The Interplanetary Magnetic Field (IMF) was oriented away from the Sun and its magnitude varied between about 3 and 9 nT. Bz was never below -5 nT for extended intervals. Solar wind conditions are expected to gradually decline on May 29 and 30.

Quiet geomagnetic conditions (K Dourbes between 0 and 2; NOAA Kp between 0 and 1) were registered in the past 24 hours. Active geomagnetic intervals (K Dourbes = 4) are possible on May 29, with a slight chance for minor storm geomagnetic levels (K Dourbes = 5). Quiet to unsettled levels (K Dourbes < 4) are expected on May 30 and 31.

Today's estimated international sunspot number (ISN): 012, based on 21 stations.

Solar indices for 28 May 2021

Wolf number Catania	///
10cm solar flux	077
AK Chambon La Forêt	005
AK Wingst	003
Estimated Ap	002
Estimated international sunspot number	028 - Based on 30 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

All times in UTC

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