Viewing archive of Tuesday, 21 August 2018

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2018 Aug 21 1238 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
21 Aug 2018	068	022
22 Aug 2018	068	026
23 Aug 2018	068	017

Bulletin

Solar activity continued to be very low with X-ray flux remaining below B level throughout the period. Field separation was observed the simple bipolar NOAA active region 2719 inhibiting only a small potential for a possible C flare. X-ray flux is thus expected to remain below C level.

The filament located around the central meridian between 35 and 50 degrees North seems to have lifted off around 19:00UT. A possibly related slow (below 300 km/s) and faint CME front can be detected in SoHO/LASCO C2 images from around 21:12UT. It is directed towards the West and has an angular extent of around 90 degrees. Due to a datagap in Stereo A COR2 data there is no more accurate information on the direction of the ejecta. Given the speed, direction and angular extent of the CME from Earth perspective no impact on Earth is expected.

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

Solar wind saw the continued influence of the coronal hole high speed stream. Solar wind speed increased before midnight to around 670 km/s before declining to around 600 km/s currently. Total magnetic field was at background values of 2-5 nT with a decaying trend. Solar wind conditions are expected to remain elevated under the influence of the high speeds from the transequatorial extension of the Southern polar coronal hole. A shock related to the August 19 CME could potentially occur within the next 24 hours but any effects should be small within the already elevated background solar wind conditions.

Geomagnetic conditions saw active periods around 18:00-21:00 UT (both local K Dourbes and NOAA Kp 4) but were otherwise quiet to unsettled (both local K Dourbes and NOAA Kp 2-3). Mainly unsettled geomagnetic conditions are expected but as solar wind speeds remain elevated and with possible CME related perturbations arriving, active periods are possible.

Today's estimated international sunspot number (ISN): 016, based on 23 stations.

Solar indices for 20 Aug 2018

Wolf number Catania	///
10cm solar flux	068
AK Chambon La Forêt	021
AK Wingst	018
Estimated Ap	018
Estimated international sunspot number	016 - Based on 24 stations

Noticeable events summary

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

All times in UTC

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