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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2015 May 19 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
19 May 2015	109	023
20 May 2015	103	017
21 May 2015	100	011

Bulletin

Until the C2.3 flare peaking just before the end of the period at 11:59UT, solar activity was quiet with all additional flaring remaining below C level. The C2.3 flare originated from the new region that rotated on disk in the northern hemisphere and which is yet unnumbered. In addition to that new region there are 6 numbered regions on disk, all with a fairly simple configuration and hence quiet conditions with possible occasional C flares are expected. A number of small eruptions were recorded from near region 2341 (around 19:55 UT), near region 2349 (around 05:55UT) and near 25N10W (around 8:40UT). Currently available coronagraphic images confirm that the first one of these events has only a narrow associated CME. The other two events are also not expected to result in any significant Earth directed CME. Solar wind was dominated by the expected onset of a high speed stream from a positive polarity equatorial coronal hole. Solar wind speed increased from around 380 km/s to 450 km/s around 18:30UT and continued to increase with current values fluctuating in the 480-550 km/s range. Total magnetic field increased from around 9 nT to over 15 nT around 19:30 UT with later a peak of 19 nT around 01:00UT, and a steady decline to below 10 nT at present. Bz was variable but with initially some pronounced negative periods down to -15 nT but later predominantly positive. In response, moderate geomagnetic storm conditions have been recorded at planetary level (NOAA Kp=6 for the 00-03UT time frame), while local geomagnetic conditions remained restricted to active levels (K Dourbes 4). Some further increase in solar wind speed is expected before the high speed stream influence will decline over the next days. Further periods of active geomagnetic conditions are to be expected subject to the orientation of the magnetic field.

Today's estimated international sunspot number (ISN): 057, based on 13 stations.

Solar indices for 18 May 2015

Wolf number Catania	///
10cm solar flux	115
AK Chambon La Forêt	038
AK Wingst	018
Estimated Ap	019
Estimated international sunspot number	069 - Based on 25 stations

Noticeable events summary

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

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