Viewing archive of Sunday, 18 April 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Apr 18 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
18 Apr 2021	076	016
19 Apr 2021	075	013
20 Apr 2021	076	005

Bulletin

Solar activity remained at very low levels over the last 24 hours. The visible active regions NOAA 2814 (Catania 86, magnetic type Beta), NOAA 2815 (not classified) and NOAA 2016 (magnetic type Beta) remained at very low levels of activity. A B9.7 class-flare (peak time 17:17 UTC) was produced on April 17th by an active region behind the east limb and resulted in a type II radio emission. The flaring activity within the next 24 hours is expected at very low to low levels with 40% chance for a C-class flare.

A CME associated with the B9.7 class-flare was detected to leave the east limb around 16:36 UTC on April 17th. It will not impact the Earth. No other Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph imagery at the moment.

The greater than 10 MeV proton flux was at nominal levels in the past 24 hours and is expected to remain so in the next 24 hours. The greater than 2MeV electron flux crossed the 1000 pfu threshold several times and is expected to remain above the threshold for long periods throughout April 18th. The 24h electron fluence reached moderate levels and is expected to remain at moderate levels in the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) remained elevated from the high speed stream (HSS) currently affecting the Earth. The total magnetic field registered a maximum magnitude of 10 nT with a minimum Bz of -10 nT. The solar wind speed varied between 570 km/s and 670 km/s. The solar wind speed is expected to remain elevated throughout April 18th.

Unsettled to active geomagnetic conditions were registered over the past 24 hours under the influence of the HSS. Unsettled to active geomagnetic conditions are expected for the next 24 hours. Isolated periods of minor geomagnetic storms remain possible in case of prolonged intervals with negative Bz.

Today's estimated international sunspot number (ISN): 016, based on 17 stations.

Solar indices for 17 Apr 2021

Wolf number Catania	///
10cm solar flux	075
AK Chambon La Forêt	031
AK Wingst	031
Estimated Ap	033
Estimated international sunspot number	018 - Based on 29 stations

Noticeable events summary

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

All times in UTC

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