Weekly Highlights of Solar and Geomagnetic Activity, 25 - 31 December 2023

[SWPC.We...@noaa.gov]

:Product: Weekly Highlights and Forecasts
:Issued: 2024 Jan 01 0215 UTC
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# Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
25 - 31 December 2023

Solar activity was at low levels on 25-30 Dec with numerous C-class
flares from Regions 3528 (N08, L=027, class/area Dai/200 on 23 Dec),
3529 (S19, L=345, class/area Dko/450 on 20 Dec), 3530 (N08, L=323,
class/area Dao/180 on 20 Dec), 3533 (N14, L=305, class/area Dao/170
on 29 Dec), 3534 (S13, L=225, class/area Dao/150 on 30 Dec) and 3536
(N05, L=152, class/area Hax/080 on 31 Dec). Activity increased to
strong levels (R3-strong) when new Region 3536 produced an X5.0
flare at 31/2155 UTC. This flare also produced complex radio burst
signatures reported across discrete frequencies, including a 10 cm
radio Burst of 3,100 sfu at 31/2143 UTC and a Type IV Sweep
signature at 31/2142 UTC. In addition to the X-flare, Region 3536
produced an M1.0 flare at 31/1912 UTC.

Numerous CME signatures, mostly from the NW and SE limbs, were
detected during the period, but none were determined to have an
Earth-directed component.

The greater than 10 MeV proton flux at geosynchronous orbit was at
slightly elevated levels to 2 pfu after 31/2310 UTC.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels.

Geomagnetic field activity was at quiet levels the entire period.
Total field strength ranged between 4-12 nT and Bz varied between
+/-7 nT. Solar wind speeds peaked at near 500 km/s early on 27 Dec
and declined to about 290 km/s early on 31 Dec. The phi angle was
mostly in a positive orientation from 25 Dec to midday on 29 Dec.
Orientation switched to a more negative angle from midday on 29 Dec
through 31 Dec.

Forecast of Solar and Geomagnetic Activity
01 January - 27 January 2024

Solar activity is expected to be low with M-class
(R1-R2/Minor-Moderate) flares likely, and a chance for X-class
(R3/Strong) flares, over 01-14 Jan, particularly from new Region
3536. From 15-27 Jan, solar activity is expected to be at low
levels, with a chance for moderate levels (R1-R2/Minor-Moderate).

There is a chance for the greater than 10 MeV proton flux to exceed
the 10 pfu event threshold on 01 Jan, and a slight chance to reach
10 pfu on 02-15 Jan. No proton events are expected from 16-27 Jan.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to reach high levels on 03-06 and 09-12 Jan due to
multiple, anticipated CH HSSs. The remainder of the outlook period
is likely to be at moderate levels.

Geomagnetic field activity is expected to be at active conditions on
01-02 Jan, with quiet to unsettled levels expected on 03-04, 08-10
and 27 Jan, due to CH HSSs. The remainder of the outlook period is
likely to be mostly quiet.