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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2021 May 01 1230 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

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

Protoni solari

Quiet

	10cm flux	Ap
01 May 2021	074	020
02 May 2021	073	031
03 May 2021	072	021

Bulletin

X-ray flux has remained below C level throughout the period. Only a single B-class flare was observed from Catania group 92 (NOAA region 2820) now approaching the West limb. X-ray flux is likely to remain below C level though an isolated C-flare is still possible.

The Eastbound CME reported yesterday is confirmed to be too far East and North and expected to miss Earth. No new Earth directed CMEs have been detected in coronagraph data.

The greater than 10 MeV proton flux was at nominal levels over the past 24 hours and is expected to remain so for the next 24 hours. The greater than 2 MeV electron flux went briefly over the 1000 pfu event threshold. The 24h electron fluence was at normal levels. Electron fluence is expected to remain at normal levels during next days.

A positive polarity coronal hole in the Southern hemisphere has transited the central meridian in the past 24 hours. It may influence Solar wind conditions from May 4 onwards.

Solar wind was in a slow Solar wind regime. Solar wind speed was mostly just above 300 km/s with a maximum of 358 km/s. Total magnetic field remained just slightly enhanced at between 4-9nT. Bz varied over the period with negative values reaching down to -6nT for a period. The magnetic field phi angle showed orientation of the interplanetary magnetic field was away from the Sun. We are expected to see in the next 24 hours an increase in the Solar wind speed associated with the positive polarity coronal hole in the Northern hemisphere that transited the central meridian earlier in the week. In addition to that we may see magnetic field perturbations due to a passing magnetic cloud from the April 26 CME, though likelihood and confidence for that arrival is low. Then towards May 4, Solar wind is expected to be again enhanced associated to the positive polarity coronal hole in the Southern hemisphere that has just passed central meridian.

Geomagnetic conditions were quiet to unsettled (NOAA Kp 1-2 and local K Dourbes 0-3). Geomagnetic conditions are expected to be quiet to active over the next days associated to the expected Solar wind perturbations, with also a chance for minor storm levels being reached.

Today's estimated international sunspot number (ISN): 011, based on 19 stations.

Solar indices for 30 Apr 2021

Wolf number Catania	///
10cm solar flux	073
AK Chambon La Forêt	013
AK Wingst	008
Estimated Ap	008
Estimated international sunspot number	029 - Based on 39 stations

Noticeable events summary

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

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