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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2015 Apr 21 1230 UTC

SIDC Forecast

Brillamenti solari

Eruptive (C-class flares expected, probability >=50%)

Geomagnetism

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

Protoni solari

Quiet

	10cm flux	Ap
21 Apr 2015	152	015
22 Apr 2015	154	041
23 Apr 2015	156	022

Bulletin

Solar flaring activity was moderate with 3 M class flares. The largest, an M2.3 flare occurred just before the end of the reporting period, peaking at 11:57 UT and originated from Catania group 28 (NOAA region 2322) near the Western limb. Another M1 flare peaking at 7:21 UT originated from that same region. The region on the Eastern limb which is about to rotate into view caused a long duration M2.2 flare peaking at 10:40UT. Only a number of very low class C flares were observed in addition. There are currently 8 numbered NOAA regions on disc and 9 Catania sunspot groups, with a new group emerging near S14W07. All are fairly unremarkable. We expect C flaring over the next days with a chance for M flaring especially from the new region that is turning onto the disc from the East. Proton fluxes were at background levels. No earth directed CME's have been observed. Solar wind was marked by the arrival of the high speed stream from a positive polarity coronal hole. Just after the start of the reporting period the magnetic field phi angle turned towards the outward direction. The total magnetic field saw a rise from 5-6 nT to about 15 nT in the compression region, while speeds were slowly rising from around 400 km/s to around 500 km/s. Magnetic field then restored to current levels around 7nT with the arrival of the core of the high speed stream around 2:00 UT, reaching a stable speed of close to 600km/s. Bz was variable in the -8nT to +12 nT range Geomagnetic conditions were locally quiet to unsettled (K Dourbes 2-3) with some active periods on the planetary level (NOAA Kp 4 in the 0UT-6UT timeframe). The high speed stream is expected to persist for the day. As its influence declines over the next day the arrival of the April 18 CME will enhance solar wind conditions again/further. Associated with the high speed stream influence some periods of active geomagnetic conditions are possible with afterwards active to minor storm conditions likely with the arrival of the April 18 CME.

Today's estimated international sunspot number (ISN): 096, based on 21 stations.

Solar indices for 20 Apr 2015

Wolf number Catania	///
10cm solar flux	150
AK Chambon La Forêt	021
AK Wingst	011
Estimated Ap	011
Estimated international sunspot number	098 - Based on 27 stations

Noticeable events summary

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

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