• Weekly Highlights of Solar and Geomagnetic Activity, 18 - 24 October 20

    From SWPC.Webmaster@noaa.gov@21:1/5 to All on Mon Oct 25 13:00:12 2021
    XPost: rec.radio.amateur.space, rec.radio.shortwave, rec.radio.info

    :Product: Weekly Highlights and Forecasts
    :Issued: 2021 Oct 25 0403 UTC
    # Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
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    # Weekly Highlights and Forecasts
    Highlights of Solar and Geomagnetic Activity
    18 - 24 October 2021

    Solar activity was very low. Background x-ray enhancement began on
    20 Oct as new Regions 2886 (S19, L= 338, class/area Hsx/185 on 19
    Oct) and 2887 (S25, L=278, class/area Dki/440 on 24 Oct) emerged
    around the SE limb on 17 Oct and 21 Oct, respectively. Region 2886
    was quiet and stable while Region 2887 produced the majority of the
    B-class flare activity. The largest flare of the period was a B9.6
    flare at 22/1838 UTC from a region just beyond the East limb. No
    Earth-directed CMEs were observed.

    No proton events were observed at geosynchronous orbit.

    The greater than 2 MeV electron flux at geosynchronous orbit was at
    normal to moderate levels with a peak flux of 433 pfu at 18/1700

    Geomagnetic field activity ranged from quiet to active levels. The
    period began under the influence of a weak transient with total
    field reaching 13 nT and the Bz component reaching -8 nT late on 17
    Oct. Solar wind speed ranged from 325-385 km/s during this time.
    Slightly perturbed conditions continued on 19-20 Oct as a solar
    sector boundary crossing followed by a co-rotating interaction
    region preceded the onset of a negative polarity coronal hole high
    speed stream (CH HSS). Solar wind speed increased to 555 km/s early
    on 21 Oct. Nominal solar wind conditions returned by midday on 23
    Oct. The geomagnetic field responded with quiet to active levels on
    18-19 Oct, quiet to unsettled conditions on 20 Oct, and quiet levels thereafter.

    Forecast of Solar and Geomagnetic Activity
    25 October - 20 November 2021

    Solar activity is expected to be at very low to low levels with a
    slight chance for M-class (R1-R2, Minor-Moderate) flares on 25 Oct -
    03 Nov as Region 2887 transits across the visible disk. Very low
    levels are expected from 04 Nov -15 Nov. Very low to low levels are
    expected again on 16-20 Nov with the return of Region 2887.

    No proton events are expected at geosynchronous orbit.

    The greater than 2 MeV electron flux at geosynchronous orbit is
    expected to be at normal to moderate levels throughout the forecast

    Geomagnetic field activity is expected to reach unsettled levels on
    27-30 Oct, 06-08 Nov, and 15-16 Nov and active levels on 06 Nov due
    to CH HSS activity.

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