Viewing archive of Saturday, 19 April 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Apr 19 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
19 Apr 2025	159	017
20 Apr 2025	162	020
21 Apr 2025	165	019

Solar Active Regions and flaring

Solar flaring activity over the last 24 hours has been moderate, with one M-class flare and few C-class flares. The strongest flare was a M4.4 flare (SIDC Flare 4156) peaking at 23:50 UTC on April 18, from beyond the east limb. There are currently seven numbered active regions on the solar disk. The most complex ones are SIDC Sunspot Group 473 and 474 (NOAA Active Regions 4062 and 4064, magnetic type beta- gamma). 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

A wide Coronal Mass Ejection (CME) was observed in LASCO/C2 and LASCO/C3 coronagraph imagery, lifting off around 00:00 UTC on April 19. It is most likely associated with the M4.4 flare (SIDC Flare 4156) that peaked at 23:50 UTC on April 18. The bulk of the ejecta is directed to the southeast. It is not expected to impact Earth. A filament eruption was observed in SDO/AIA 304 data around 18:45 UTC on April 18, near SIDC Sunspot Group 473 (NOAA Active Region 4062). No associated CME was observed in the available coronagraph imagery. No other Earth-directed 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. An equatorial, positive polarity coronal hole (returning SIDC Coronal Hole 82) is crossing the central meridian. An associated high-speed stream may arrive at Earth starting from the UTC evening of April 21.

Solar wind

The solar wind conditions (ACE and DSCOVR) are gradually returning to the slow solar wind regime. The solar wind speed has decreased to around 400 km/s. The interplanetary magnetic field was between 4 nT and 7 nT. The Bz component was mostly negative, with values between -6 nT and 4 nT. The interplanetary magnetic field angle was predominantly in the negative sector. Enhanced solar wind conditions may be expected over the next 24 hours, due to the possible arrival of a high-speed stream from the southern, positive polarity coronal hole (SIDC Coronal Hole 104).

Geomagnetism

Geomagnetic conditions globally reached active levels (NOAA Kp 4) between 00:00 UTC and 03:00 UTC and later between 06:00 UTC and 09:00 UTC on April 19. Geomagnetic conditions locally were mostly at unsettled levels (K BEL 3), reaching active levels between 23:00 UTC on April 18 and 00:00 UTC on April 19 and later between 02:00 UTC and 05:00 UTC on April 19. Mostly unsettled to active levels, with possible minor storm intervals (NOAA Kp 3 to 5, K BEL 3 to 5), are expected globally and locally over the next 24 hours, due to the possible arrival of a high-speed stream from the southern, positive polarity coronal hole (SIDC Coronal Hole 104).

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): 106, based on 10 stations.

Solar indices for 18 Apr 2025

Wolf number Catania	142
10cm solar flux	156
AK Chambon La Forêt	025
AK Wingst	018
Estimated Ap	019
Estimated international sunspot number	114 - Based on 19 stations

Noticeable events summary

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

All times in UTC

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