Viewing archive of Thursday, 20 April 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Apr 20 1259 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
20 Apr 2023	150	007
21 Apr 2023	150	017
22 Apr 2023	150	011

Bulletin

Solar flaring activity remained at low levels in the past 24 hours. There are six active regions on the visible solar disc. The largest one, NOAA AR 3282 (beta), has shown only occasional low levels of flaring activity. The strongest activity was a C3.6 flare with peak time 09:22 UTC on April 19th produced by NOAA AR 3281 (beta), which together with NOAA AR 3272 from behind the west limb and an active region behind the east limb was responsible for most of the flaring activity. NOAA AR 3281 (beta) has shown some decay, decreasing the number of trailing spots. Minor C-class flaring was produced by NOAA AR 3283 (beta). The solar flaring activity is expected to be at low levels over the next 24 hours with low chances for isolated M-class flaring.

A filament erupted near NOAA 3283 around 23:30 UTC on April 19th and a south-east coronal mass ejection (CME) was detected by LASCO/C2 around 23:24 UTC. Current analysis suggests that this CME will miss Earth. No other Earth-directed CMEs have been detected in the available coronagraph imagery.

Over the past 24 hours the greater than 10 MeV GOES proton flux was at nominal levels and is expected to remain so in the next 24 hours. The greater than 2 MeV electron flux has been below the1000 pfu threshold and is expected to remain so. The 24h electron fluence was at nominal levels and is expected to remain so over the next 24 hours.

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) are indicative of an ongoing weak ICME arrival. The solar wind velocity varied between 390 km/s and 496 km/s. The interplanetary magnetic field registered a maximum value of 10.9 nT with a weak minimum Bz of -6.8 nT. The B field was switching orientation between the positive and the negative sector (directed away from and towards the Sun). Elevated solar wind conditions are expected to prevail on April 20th and April 21st with ongoing ICME influence and a possible second ICME arrival. A patchy negative polarity equatorial coronal hole has crossed the central meridian on April 18th and mild high speed stream might be expected to reach Earth on April 22nd.

The geomagnetic conditions over the past 24 hours were quiet to active. Quiet to unsettled geomagnetic conditions are expected over the next 24 hours with probable active periods and chances of reaching minor storm levels pending the possible new ICME arrival.

Today's estimated international sunspot number (ISN): 100, based on 11 stations.

Solar indices for 19 Apr 2023

Wolf number Catania	120
10cm solar flux	147
AK Chambon La Forêt	013
AK Wingst	011
Estimated Ap	012
Estimated international sunspot number	108 - Based on 28 stations

Noticeable events summary

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

All times in UTC

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