Viewing archive of Thursday, 4 November 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Nov 04 1301 UTC

SIDC Forecast

Solar flares

C-class flares expected, (probability >=50%)

Geomagnetism

Moderate (ISES: Major) magstorm expected (A>=50 or K=6)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
04 Nov 2021	088	066
05 Nov 2021	086	037
06 Nov 2021	084	013

Bulletin

The strongest flare of the period was a C5.2 flare peaking at 21:17 from NOAA active region 2887 (Catania group 66) as it is turning over the Western limb. The simple unipolar NOAA region 2893 (Catania group 68) remained quiet as did the NOAA region 2891 (Catania group 67) which seems to evolve towards a unipolar spot. A new region is also turning onto the Southern hemisphere in the East, which produced a C3.5 flare peaking at 10:55UT. Overall, further C flares are expected in the next 24 hours with only a minor possibility of an M flare.

No new Earth directed CMEs have been recorded in coronagrpah data.

The more than 10MeV proton flux remained slightly enhanced and briefly peaked over the event threshold at 20:55UT with the arrival of the CME. A gentle decay is expected but there remains some possibility of a proton event. The greater than 2 MeV electron flux was below the 1000 pfu threshold. The 24h electron fluence is at normal levels and expected to be at normal to moderate levels over the next days.

Solar wind saw the arrival of the expected series of CMEs, somewhat earlier than anticipated. Given the measured Solar wind velocity it is likely that the observed ICME is related to the November 2 CME that most probably caught up with the preceding CMEs. A shock was observed in Solar wind data as recorded by DSCOVR when at 19:24UT Solar wind speed jumped from 498km/s to 542 km/s and the interplanetary magnetic field jumped from 4nT to 9nT. Since then Solar wind speed fluctuated around 700 km/s and the interplanetary magnetic field peaked over 20nT and was consistently in the 10-24nT range. Bz was negative for a significant amount of time with values down to -18nT. Solar wind is expected to remain enhanced for the remainder of the day and into November 5 as the CME(s) pass.

Geomagnetic conditions reached minor to major storm levels (NOAA Kp reaching 7 while local K Dourbes reached 6). Further minor to moderate geomagnetic storms can be expected as the CME(s) pass.

Today's estimated international sunspot number (ISN): 026, based on 18 stations.

Solar indices for 03 Nov 2021

Wolf number Catania	050
10cm solar flux	089
AK Chambon La Forêt	056
AK Wingst	026
Estimated Ap	024
Estimated international sunspot number	034 - Based on 22 stations

Noticeable events summary

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

All times in UTC

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