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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2025 May 03 1231 UTC

SIDC Forecast

Brillamenti solari

M-class flares expected (probability >=50%)

Geomagnetism

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

Protoni solari

Quiet

	10cm flux	Ap
03 May 2025	152	025
04 May 2025	152	013
05 May 2025	152	025

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares recorded. A total of three sunspot groups were visible on the solar disk during this period. The most complex of these, SIDC Sunspot Group 469 (NOAA Active Region 4079), currently located at N08E25, has a Beta-Gamma-Delta magnetic configuration and remained stable throughout the reporting period. This region was responsible for all observed flaring activity, including the largest event: a C3.6 flare (SIDC Flare 4276), which peaked on May 2 at 21:43 UTC. Given the complexity of this region, solar flaring activity is expected to be moderate over the next 24 hours, with C-class flares likely and a reasonable chance of M-class flares.

Espulsioni di massa coronale

Several filaments are visible on the solar disk; however, they appear stable at this time. No Earth-directed coronal mass ejections (CMEs) were observed in the available coronagraph imagery over the past 24 hours.

Fori coronali

SIDC Coronal Hole 109 (an equatorial coronal hole with negative polarity) and SIDC Coronal Hole 110 (a high-latitude coronal hole with negative polarity), both of which first crossed the central meridian on May 1, appear to have merged over the past 24 hours to form a trans- equatorial coronal hole. This merged structure is now positioned on the western side of the Sun.

Vento solare

The Earth remains under the influence of an enhanced solar wind stream, with speeds increasing and currently ranging between 700 and 800 km/s. The total interplanetary magnetic field (IMF) remains elevated, reaching a peak of 13.6 nT. The southward component of the IMF (Bz) has remained mostly negative, with a minimum of -11.2 nT recorded. The phi angle remains in the negative sector, confirming continued magnetic connection to the high-speed solar wind stream associated with SIDC Coronal Hole 99, a large trans-equatorial coronal hole with negative polarity. These conditions are expected to persist over the next few days as the influence of this coronal hole continues. Looking ahead, in approximately one to two days, following a very brief period of relative calm, solar wind speeds may increase again. This would likely result from the influence of two smaller coronal holes (SIDC Coronal Hole 109 and SIDC Coronal Hole 110) that appear to have merged over the past 24 hours into a trans-equatorial coronal hole with negative polarity. Both coronal holes crossed the central meridian on May 1.

Geomagnetism

Geomagnetic conditions remain elevated, with Kp-NOAA reaching 5+ and K_BEL holding at 4, indicating the ongoing presence of a minor geomagnetic storm. This activity is driven by the continued influence of a high-speed solar wind stream associated with SIDC Coronal Hole 99 (a large, elongated trans-equatorial coronal hole with negative polarity that crossed the central meridian on April 29) and by the interplanetary magnetic field (IMF), whose Bz component has remained predominantly negative. Mostly active conditions, with possible minor storm intervals, are expected to persist over the next 24 hours before gradually declining as the solar wind stream weakens.

Proton flux levels

No enhancement or solar energetic particle event has been detected over the past 24 hours. The greater-than-10 MeV proton flux remained at low levels over the past 24 hours and is expected to stay below the event threshold in the next 24 hours.

Electron fluxes at geostationary orbit

The greater-than-2 MeV electron flux measured by GOES 18 and GOES 19 fluctuated and exceeded the threshold level over the past 24 hours, in response to the ongoing high-speed solar wind stream currently affecting Earth. The 24-hour electron fluence remains at normal levels but may become elevated and reach moderate levels due to the continued influence of enhanced solar wind conditions.

Today's estimated international sunspot number (ISN): 061, based on 19 stations.

Solar indices for 02 May 2025

Wolf number Catania	///
10cm solar flux	152
AK Chambon La Forêt	038
AK Wingst	030
Estimated Ap	035
Estimated international sunspot number	044 - Based on 32 stations

Noticeable events summary

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

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