Viewing archive of Saturday, 20 May 2017

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2017 May 20 1230 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
20 May 2017	072	021
21 May 2017	072	024
22 May 2017	072	021

Bulletin

In the past 24 hours, no C flares were observed. Very low solar activity (no C flares) is expected in the next 24 hours. Solar wind speed measured by DSCOVR varied between about 430 and 490 km/s until around 18:30 UT on May 19, when it started rising to a plateau around 600 km/s. At 8:52 UT on May 20, the solar wind speed jumped to about 710 km/s. The magnitude of the Interplanetary Magnetic Field (IMF) varied between about 5 and 15 nT until 8:52 UT on May 20, when it fell from 13 to 6 nT. These are clear signs of the arrival of the predicted high speed stream from a negative equatorial coronal hole. Bz was regularly between -5 and -10 nT between 5h and 9h UT. Unsettled geomagnetic conditions (K Dourbes equal to 3; NOAA Kp between 2 and 4) were registered in the past 24 hours. Active (K Dourbes = 4) to minor storm conditions (K Dourbes = 5) are possible on May 20, 21 and 22, due to the arrival the predicted high speed stream.

Today's estimated international sunspot number (ISN): 032, based on 20 stations.

Solar indices for 19 May 2017

Wolf number Catania	028
10cm solar flux	072
AK Chambon La Forêt	024
AK Wingst	016
Estimated Ap	016
Estimated international sunspot number	023 - Based on 23 stations

Noticeable events summary

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

All times in UTC

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