Viewing archive of Wednesday, 21 April 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Apr 21 1245 UTC

SIDC Forecast

Solar flares

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Apr 2021	082	008
22 Apr 2021	078	010
23 Apr 2021	077	006

Bulletin

During last 24 hours several B-class and two C-class flares were reported. The C1.9 flare which was observed on April 20 (peaked at 12:15 UT), originated from the NOAA AR 2814 situated at the West solar limb. The C1.5 flare, which originated from the close to the West solar limb region NOAA AR 2817, was observed on April 21 (peaked at 01:29 UT). Both flares were associated with narrow CMEs that are not expected to arrive to Earth. We expect solar flaring activity to stay on the similar level with B-class flares and occasional C-class flares possible. Although still possible M-class flares are not very probable. During last 24 hours the proton flux levels remained at background values.

The greater than 2MeV electron flux is above the 1000 pfu threshold, and it is expected to remain so for long periods throughout April 21. The 24h electron fluence is at moderate to high level and is expected to stay so in the next 24 hours.

The solar wind speed is presently about 530 km/s and the interplanetary magnetic field magnitude is about 3 nT. During last 24 hours geomagnetic conditions were mostly unsettled. Only one interval of active conditions was reported by local station at Dourbes in the evening of April 20 (around 19:00 UT). We expect such geomagnetic conditions to persist in the coming hours.

Today's estimated international sunspot number (ISN): 043, based on 20 stations.

Solar indices for 20 Apr 2021

Wolf number Catania	065
10cm solar flux	080
AK Chambon La Forêt	020
AK Wingst	015
Estimated Ap	015
Estimated international sunspot number	054 - Based on 34 stations

Noticeable events summary

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

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