Viewing archive of Sunday, 27 April 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Apr 27 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
27 Apr 2025	156	016
28 Apr 2025	154	013
29 Apr 2025	152	007

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, only minor C-class flaring was observed. A total of 15 numbered sunspot groups were identified on the disk over the past 24 hours, all with simple alpha or beta magnetic field configuration, and most of them are decaying. The largest flare was a C1.3 one from SIDC Sunspot Group 468 currently located at S15E87, with beta magnetic field confuration. Solar flaring activity is expected to be low over the next 24 hours, with C-class flares expected.

Coronal mass ejections

A wide CME erupted towards the north, first seen at 18:00 UTC on 26 April on LASCO C2, but is is not expected to arrive to the Earth. No Earth-directed CMEs were observed in the available coronagraph imagery in the last 24 hours.

Coronal holes

There is a large positive polarity coronal hole (SIDC Coronal Hole 104) in the southern hemisphere, although parts of it have rotated out of view over the west limb. In the northern hemisphere, there is one smaller, positive polarity coronal hole, that crossed the central meridian on 24 April. On the eastern part of the Sun, there is a recurrent transequatorial elongated negative polarity coronal hole, SIDC Coronal Hole 99.

Solar wind

The solar wind speed has been gradually decreasing to around 400 km/s in the last 24 hours, with an interplanetary magnetic field of 5-10 nT, and Bz mostly positive. In the next 24 hours we may see the arrival of a high speed stream if the solar wind from the positive polarity coronal holes in the southern and/or in the northern hemisphere arrive to the Earth.

Geomagnetism

Geomagnetic conditions have been quiet globally and locally (Kp and K_Bel up to 2). The possible arrival of a high speed solar wind stream may increase conditions to active levels. Otherwise, mostly quiet conditions can be expected.

Proton flux levels

The greater than 10 MeV proton flux was below the threshold level over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and 19has been at, or slightly below, the threshold over the past 24 hours. The greater than 2 MeV electron flux may increase over the next 24 hours.The 24-hour electron fluence is presently between normal and moderate levels, it may increase over the next 24 hours.

Today's estimated international sunspot number (ISN): 125, based on 19 stations.

Solar indices for 26 Apr 2025

Wolf number Catania	///
10cm solar flux	156
AK Chambon La Forêt	009
AK Wingst	006
Estimated Ap	006
Estimated international sunspot number	170 - Based on 21 stations

Noticeable events summary

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

All times in UTC

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