Subject: Weekly Highlights of Solar and Geomagnetic Activity, 16 - 22 December 2024

:Product: Weekly Highlights and Forecasts
:Issued: 2024 Dec 23 0521 UTC
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# Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
16 - 22 December 2024

Solar activity reached moderate levels on 19-22 Dec due to low level
M-class activity from Regions 3924 (S18, L=317, class/area Eko/300
on 18 Dec), 3928 (S13, L=175, class/area Dki/260 on 22 Dec), 3930
(S20, L=258, class/area Cai/100 on 20 Dec), and 3932 (S17, L=480,
class/area Ekc/480 on 22 Dec). The largest flare was an M3.8 at
19/1534 UTC from Region 3928. Slight to moderate growth was observed
in sunspot regions 3928, 3932, and 3933 (S07, L=174, class/area
Dko/260 on 22 Dec) beginning on 21 Dec in the SE quadrant. Other
activity included a CME off the NNE limb at 20/2324 UTC associated
with flaring in the vicinity of N22E08. Subsequent modelling
indicated the potential for a grazing early to midday on 24 Dec. No
further Earth-directed CMEs were observed.

No proton events were observed at geosynchronous orbit, however
three proton enhancements occurred from 16/1820-17/0630 UTC with a
maximum of 0.41 pfu at 17/0210 UTC, 17/1840-17/2130 UTC with a
maximum of 0.72 pfu at 17/1915 UTC, and again from 20/1015 UTC till
the end of the reporting period with a current maximum of 5.25 pfu
at 22/0625 UTC. The early enhancements could be related to a large
CME just beyond the SE limb occurring at 15/1441 UTC. The
enhancement on 20 Dec could be attributed to a large prominence
eruption just beyond the SW limb at 19/1241 UTC.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels with a peak flux of 757 pfu observed at
21/1955 UTC.

Geomagnetic field activity ranged from quiet to G1 (Minor) storm
levels. The solar wind began the period near nominal levels on 16
Dec with solar wind speed near 400 km/s and total field slightly
enhanced ranging from 5-10 nT. The geomagnetic field was at quiet to
unsettled levels. At 17/0442 UTC, a shock arrival was observed at
the ACE spacecraft, likely due to influences associated with CMEs
that occurred on 13-15 Dec. Total field increased to a maximum of 30
nT at 17/0633 UTC before declining to around 10 nT at 17/1600 UTC.
Solar wind speed increased to a maximum of 701 km/s at 17/0821 UTC
before declining to 500-600 km/s by 17/1930 UTC. A further decline
in solar wind speed to around 440 km/s was observed around midday on
19 Dec. The geomagnetic field responded with mostly active to G1
(Minor) storming on 17 Dec followed by quiet to active levels on
18-19 Dec. Quiet to active levels continued through 21 Dec as the
solar wind likely transitioned into a negative polarity CH HSS with
solar wind speeds increasing to near 700 km/s by 22/1315 UTC before
slowly decreasing to near 580 km/s by the end of the period. Quiet
to unsettled levels were observed on 22 Dec.

Forecast of Solar and Geomagnetic Activity
23 December - 18 January 2025

Solar activity is expected to continue at low to moderate (R1-R2, Minor-Moderate) levels throughout the period with a chance for
X-class flares (R3, Strong) through 01 Jan, primarily due to the
growth and increased complexity of Regions 3928, 3932, and 3933.

There is a slight chance for a greater than 10 MeV proton event
reaching the S1 (Minor) level through 03 Jan due to the flare
potential of Regions 3928, 3932, and 3933.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to continue at normal to moderate levels with a chance for
high levels on 23-25 Dec due to HSS influence.

Geomagnetic field activity is expected to reach unsettled to active
levels on 23-27 Dec due to HSS influence couple with a possible
grazing from the 20 Dec CME around midday on 24 Dec. Unsettled to
active levels are expected again on 05-06 Jan, 10-12 Jan, and 16-18
Jan due to recurrent CH HSS effects.


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* Origin: NOAA Space Weather Prediction Center (3:633/280.2@fidonet)