Viewing archive of Saturday, 25 August 2018

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2018 Aug 25 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
25 Aug 2018	072	021
26 Aug 2018	072	021
27 Aug 2018	071	008

Bulletin

NOAA active region 2720 has been growing steadily and was the source of a series of B flares over the period. The strongest was a B4.1 flare peaking at 10:48UT. The other region on disk (NOAA 2719) seemed to be in decay at the end of the period. Overall probability for the occurrence of a C-flare remains low (around 20%).

No Earth directed CMEs have been identified in coronagraph data.

Proton flux levels were at background values and are expected to remain so.

Solar wind speed continued to decrease (to as low as 320 km/s) until around midnight when a steady increase to current values of 400 km/s set in. Throughout the period, the magnetic field was only slightly elevated (mostly 5-8 nT), but with the magnetic field rotation indicating that this is indeed the passing of a magnetic cloud as expected from the august 20 CME. More recently, magnetic field strength reached up to 10 nT. Apart from at the start of the period, Bz has been mostly positive throughout the period. Solar wind conditions are expected to remain elevated over the next 24 hours but with a decreasing trend.

Geomagnetic conditions were mostly quiet (local K Dourbes and NOAA Kp 0-2) apart from an isolated period of unsettled (K=3) conditions both locally and in terms of Kp at the start of the period, related to the negative Bz at that time. Geomagnetic conditions may still see active periods over the next 24 hours should the enhanced magnetic field show persistent periods of Southward orientation. Later, geomagnetic conditions should remain quiet to unsettled.

Today's estimated international sunspot number (ISN): 034, based on 18 stations.

Solar indices for 24 Aug 2018

Wolf number Catania	///
10cm solar flux	072
AK Chambon La Forêt	008
AK Wingst	006
Estimated Ap	005
Estimated international sunspot number	029 - Based on 28 stations

Noticeable events summary

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

All times in UTC

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