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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2018 Apr 20 1230 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

Minor storm expected (A>=30 or K=5)

Protoni solari

Quiet

	10cm flux	Ap
20 Apr 2018	073	035
21 Apr 2018	072	013
22 Apr 2018	072	009

Bulletin

The sunspot group which appeared from the behind of the East solar limb yesterday got numbered as Catania sunspot group 78 (NOAA AR 2706). This sunspot group was source of the all (low B-class), flaring activity during last 24 hours. We expect that Catania sunspot group 78 might be the source of the B-class flares and possibly also isolated C-class flare in the following 24 hours. There were no Earth directed CMEs observed since the last report and the solar protons remain at the background level.

The in situ observations showed sudden increase of the interplanetary magnetic field magnitude (IMF), solar wind speed, density and temperature at about 23:19 UT yesterday evening. All this indicates arrival of the shock wave, however presently it is still unclear if the shock wave will be followed by the ICME or this is a shock in the solar wind related with the expected arrival of the fast flow. The shock wave was followed by gradual increase of the solar wind speed and IMF. The fast solar wind (up to 515 km/s) and longer intervals of negative values of the Bz component of the IMF (down to -19 nT), resulted in the active to storm geomagnetic conditions reported this morning (local station at Dourbes reported K=5 and NOAA reported Kp=6). The solar wind speed is presently about 480 km/s and the IMF is about 14 nT. If the solar wind speed will continue to increase and the Bz component will show longer intervals with negative values we can expect continuation of the disturbed geomagnetic conditions in the coming hours.

Today's estimated international sunspot number (ISN): 015, based on 27 stations.

Solar indices for 19 Apr 2018

Wolf number Catania	012
10cm solar flux	071
AK Chambon La Forêt	011
AK Wingst	002
Estimated Ap	002
Estimated international sunspot number	007 - Based on 39 stations

Noticeable events summary

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

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