Viewing archive of Friday, 18 April 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Apr 18 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
18 Apr 2025	153	011
19 Apr 2025	155	014
20 Apr 2025	157	017

Solar Active Regions and flaring

Solar flaring activity over the last 24 hours has been low, with few C-class flares only. The strongest flare was a C4.6 flare (SIDC Flare 4149) peaking at 14:22 UTC on April 17, associated with SIDC Sunspot Group 474 (NOAA Active Region 4064, magnetic type beta). There are currently seven numbered active regions on the solar disk. The most complex one is SIDC Sunspot Group 450 (NOAA Active Region 4060, magnetic type beta-delta). A new, currently unnumbered active region (SIDC Sunspot Group 478, magnetic type beta) has rotated on disk from the east limb. The solar flaring activity is expected to be low to moderate over the next 24 hours, with C-class flares expected and M-class flares probable.

Coronal mass ejections

No Earth-directed Coronal Mass Ejections (CMEs) were observed in the available coronagraph imagery.

Coronal holes

The southern, mid-latitude, positive polarity coronal hole (SIDC Coronal Hole 104) continues to cross the central meridian since April 17. An associated high-speed stream may arrive at Earth starting from the UTC evening of April 19.

Solar wind

The solar wind conditions (ACE and DSCOVR) were enhanced over the last 24 hours, under the waning effect of the interplanetary Coronal Mass Ejection (ICME) arrivals, associated with the CMEs that lifted on April 12 and April 13, and a possible high-speed stream arrival from SIDC Coronal Hole 105. The solar wind speed was mostly around 450 km/s. The interplanetary magnetic field decreased from 13 nT to 7 nT. The Bz component was mostly positive, decreasing from 11 nT to 2 nT, with a period of negative values (reaching a minimum of -10 nT) between 00:30 UTC and 05:30 UTC on April 18. The interplanetary magnetic field angle was predominantly in the negative sector. Currently, the solar wind speed is around 450 km/s, the interplanetary magnetic field around 6 nT and the Bz component between 1 nT and 5 nT. Enhanced solar wind conditions may be expected over the next 24 hours.

Geomagnetism

Geomagnetic conditions globally reached active levels (NOAA Kp 4) between 06:00 UTC and 09:00 UTC on April 18. Geomagnetic conditions locally were mostly at unsettled levels (K BEL 3) until 06:00 UTC on April 18 and have since decreased to quiet levels (K BEL 2). Mostly unsettled to active levels (NOAA Kp 3 to 4, K BEL 3 to 4) are expected globally and locally over the next 24 hours.

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 GOES 19 was below the threshold over the past 24 hours. The greater than 2 MeV electron flux is expected to remain below the threshold over the next 24 hours. The 24-hour electron fluence is presently at normal levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 114, based on 11 stations.

Solar indices for 17 Apr 2025

Wolf number Catania	///
10cm solar flux	151
AK Chambon La Forêt	018
AK Wingst	011
Estimated Ap	012
Estimated international sunspot number	099 - Based on 16 stations

Noticeable events summary

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

All times in UTC

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