Viewing archive of Saturday, 13 April 2013

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2013 Apr 13 1248 UTC

SIDC Forecast

Solar flares

Active (M-class flares expected, probability >= 50%)

Geomagnetism

Severe geomagnetic storm expected (A>=100 or K>=7)

Solar protons

Warning condition

	10cm flux	Ap
13 Apr 2013	140	039
14 Apr 2013	142	045
15 Apr 2013	143	008

Bulletin

Catania sunspot groups 40 and 43 (NOAA ARs 1718 and 1719 respectively) show the signs of decay, although these two active regions (as well as Catania sunspot group 45, NOAA AR 1721) have beta-gamma configuration of the photospheric magnetic field. M3.3 flare was detected on April 12 peaking at 20:38 UT in the Catania sunspot group 40 (NOAA AR 1718). It was not associated with a CME. The delta sunspot in the Catania sunspot group 43 (NOAA AR 1719) does not exist anymore, so an X-flare (and an SEP event) is not very likely (although an Earth-directed CME remains possible). We expect further flaring activity on the M-level, with a non-negligible chance for an isolated X-class flare. The proton flux at energies above 10 MeV is currently below the SEP event threshold, although it still exceeds significantly the background level. In such a situation, a relatively small increase of the proton flux at the expected shock arrival may lead to crossing the SEP event threshold again. The Earth is currently inside a slow (around 400 km/s) solar wind flow with average (around 4 nT) interplanetary magnetic field magnitude. We expect quiet geomagnetic conditions until the arrival (expected later today) of the interplanetary disturbance produced by the halo CME of April 11. The occurrence of a strong geomagnetic storm (K index around 7) will be probable.

Today's estimated international sunspot number (ISN): 080, based on 13 stations.

Solar indices for 12 Apr 2013

Wolf number Catania	125
10cm solar flux	138
AK Chambon La Forêt	010
AK Wingst	005
Estimated Ap	004
Estimated international sunspot number	081 - Based on 20 stations

Noticeable events summary

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

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