• Weekly Highlights of Solar and Geomagnetic Activity, 18 - 24 August 2025

    From SWPC.Webmaster@SWPC.Webmaster@noaa.gov to rec.radio.amateur.dx,rec.radio.amateur.space,rec.radio.shortwave,rec.radio.info on Mon Aug 25 13:00:04 2025
    From Newsgroup: rec.radio.amateur.space

    :Product: Weekly Highlights and Forecasts
    :Issued: 2025 Aug 25 0309 UTC
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    # Weekly Highlights and Forecasts
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    Highlights of Solar and Geomagnetic Activity
    18 - 24 August 2025

    Solar activity was at low levels on 18, 20, and 21 Aug with only
    C-class flares observed. Activity increased to moderate levels on 19
    Aug following an M1.1 flare at 19/0439 UTC from an area beyond the
    Eastern limb. Moderate levels were also observed on 22 Aug as Region
    4191 (N11, L=172, class/area=Ehi/360 on 24 Aug) produced a
    long-duration M1.7/Sf flare at 22/1851 UTC. Associated with this
    flare was a Type II radio sweep with an estimated shock speed of 521
    km/s. The associated CME was deemed to be behind the Sun-Earth line.
    Moderate levels continued into 23 and 24 Aug with an M1.9 at 23/2006
    UTC and an M1.3 flare at 24/0836 UTC, both originating from beyond
    the NE limb. While multiple CMEs were observed in coronagraph
    imagery over the period, nearly all were at or beyond the Eastern
    limb and none were considered to have an Earth-directed component.

    The greater than 10 MeV proton flux at geosynchronous orbit was at
    background levels from 18-22 Aug. Beginning around midday on 22 Aug,
    flux levels began to rise following the long-duration M1.7 flare
    event, mentioned above. Levels continued to rise, eventually
    reaching a peak of 8.3 pfu at 24/2330 UTC, but never exceeded the
    greater than 10 pfu levels.

    The greater than 2 MeV electron flux at geosynchronous orbit was at
    normal to moderate levels on 19-20 Aug, and 22-23 Aug. Activity
    reached high levels on 18, 21, and 24 Aug, with the peak observed
    value of 2,200 pfu at 18/0830 UTC.

    Geomagnetic field activity was at quiet to unsettled levels on 18
    and 24 Aug, bookending a negative polarity coronal hole high speed
    stream. Unsettled to active conditions were observed on 20-23 Aug as
    CH HSS activity elevated, with active to minor storm levels observed
    on 19 Aug.



    Forecast of Solar and Geomagnetic Activity
    25 August - 20 September 2025

    Solar activity is expected to be at low levels, with varying chances
    for M-class flares (R1-R2/Minor-Moderate events) through 20 Sep.

    The greater than 10 MeV proton levels are expected to be at or above
    10 pfu levels on 25 Aug before dropping below the 10 pfu level by 26
    Aug. Levels should remain below thresholds through 20 Sep, with no
    additional events expected at geosynchronous orbit.

    The greater than 2 MeV electron flux at geosynchronous orbit is
    expected to be at moderate levels on 25-26 Aug, 29 Aug-5 Sep, and
    15-19 Sep. Conditions are likely to see high levels on 27-28 Aug,
    6-14 Sep, and again on 20 Sep.

    Geomagnetic field activity is expected to be at mostly quiet levels
    on 29 Aug-3 Sep and again on 11-14 Sep. Unsettled levels are likely
    on 25-28 Aug, 7-10 Sep, and 17-20 Sep. Active conditions are likely
    on 4-9 Sep and 15-16 Sep, with possible minor storming on 4-6 Sep
    and 15 Sep. All increased activity levels are associated with
    coronal hole high speed stream influence.

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