Viewing archive of Thursday, 21 July 2016

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2016 Jul 21 1230 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
21 Jul 2016	109	012
22 Jul 2016	108	018
23 Jul 2016	107	021

Bulletin

During the first half of the period, the magnetic configuration around NOAA 2567's main spot became more complex with a weak delta to the north and a filament south of the main spot. Flaring activity intensified with an impulsive M1.2 (peak at 00:46UT) and an M1.0 (peak at 01:49UT) being the strongest events. There were also 7 C-class flares, originating all from this region or near the inversion line with NOAA 2565. NOAA 2565 and NOAA 2569 were quiet.

There is a reasonable chance on another M-class flaring episode, in particular from NOAA 2567.

Starting around 22:30UT (20 July), CACTus reported coronal mass ejections (CMEs) directed to the northeast (22:24UT) and southwest (22:36UT), and each about 50 degrees wide. With no obvious activity on the Sun's farside or eastern hemisphere, it is very likely that these CMEs were related to a C4.6 flare that peaked at 22:17UT in NOAA 2567. Sagamore Hill reported a Type II radio burst with associated shock speed of 1168 km/s. Assuming these CMEs have an earth-directed component, the geomagnetic field may be impacted late on 22 or on 23 July. These results are preliminary and may be further finetuned.

Solar wind speed decreased from 600 to 430 km/s. Bz was mostly positive, varying between +2 and +12 nT, and ending the period at a steady +7 nT. The interplanetary magnetic field was directed towards the Sun (negative). Quiet to unsettled geomagnetic conditions were observed.

Mostly quiet to unsettled geomagnetic conditions are expected. Active to minor storming episodes are possible in response to the high speed stream of the negative northern coronal hole later today or tomorrow, and from the possible impact of the 20 July CME late on 22 or on 23 July.

Today's estimated international sunspot number (ISN): 055, based on 24 stations.

Solar indices for 20 Jul 2016

Wolf number Catania	065
10cm solar flux	108
AK Chambon La Forêt	014
AK Wingst	023
Estimated Ap	025
Estimated international sunspot number	059 - Based on 33 stations

Noticeable events summary

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

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