Subject: Weekly Highlights of Solar and Geomagnetic Activity, 20 - 26 February 2023

:Product: Weekly Highlights and Forecasts
:Issued: 2023 Feb 27 0249 UTC
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# Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
20 - 26 February 2023

Solar activity reached high levels this week. A total of nine R1
(Minor) events and two R2 (Moderate) events were observed this
period. Region 3229 (N26, L=34, class/area=Ekc/310 on 20 Feb)
produced two significant flares which were followed by proton flux
enhancements and subsequent Earth-directed CMEs. The first event was
a long-duration M3/2b flare at 24/2030 UTC with Type-II (1,204 km/s)
and Type-IV radio emissions. Shortly following the flare, the
greater than 10 MeV proton flux became enhanced, reaching a peak
flux of 3 pfu observed at 24/2355 UTC, but did not exceed the event
threshold. The associated CME arrived at Earth beginning at around
26/1845 UTC. The second flare of note from Region 3229 was a
long-duration M6/3n flare at 25/1944 UTC with Type-II (528 km/s)
radio emissions observed. Shortly following this second flare, the
greater than 10 MeV proton flux exceeded the S1 (Minor) solar
radiation storm threshold at 25/2110 UTC, and reached a peak flux of
58 pfu at 26/0440 UTC. The partial-halo CME from the M6 flare was
determined to have an Earth-directed component, and is expected to
arrive late on 27/early on 28 Feb.

The greater than 10 MeV proton flux became slightly enhanced late on
24/early on 25 Feb following an M3 flare at 24/2030 UTC from Region
3229. A peak flux of 3 pfu was observed at 24/2355 UTC before flux
values slowly decreased to around 1 pfu. An additional enhancement
of the greater than 10 MeV proton flux was observed shortly
following an M6 flare at 25/1944 UTC from Region 3229. This second
proton enhancement exceeded the S1 (Minor) solar radiation storm
threshold at 25/2110 UTC, and a peak flux of 58 pfu was observed at
26/0440 UTC. Proton flux values began decreasing over the latter
half of 26 Feb, but remained near the 10 pfu event threshold.

The greater than 2 MeV electron flux at geosynchronous orbit was
normal to moderate throughout the week.

Geomagnetic field activity was quiet to unsettled on 20 Feb, and
quiet to active on 21 Feb, in response to positive polarity CH HSS
influence. Quiet conditions prevailed on 22 Feb. G1 (Minor) storm
conditions were observed on 23 Feb due to the passage of a CME.
Quiet to unsettled levels were observed over 24-25 Feb, with
negative polarity CH HSS influences observed on 25 Feb. G2
(Moderate) storm conditions were observed late on 26 Feb due to a
combination of negative polarity CH HSS influences as well as the
arrival of the 24 Feb CME. An interplanetary shock (34 nT as
measured by Fredericksburg magnetometer) associated with the arrival
of the 24 Feb CME was observed at 26/1845 UTC in solar wind data.
Following the shock, total magnetic field strength values increased
to 21 nT and the Bz component reached -18 nT, solar wind speeds
increased to a peak of 756 km/s, and solar wind density increased to
32 ppcm.

Forecast of Solar and Geomagnetic Activity
27 February - 25 March 2023

Solar activity is expected to be elevated throughout the outlook
period. A number of regions with a history of producing M-class and
X-class flares are expected to return and transit the solar disk
over the course of the next 27 days.

The greater than 10 MeV proton event that began at 25/2110 UTC
decreased below event threshold at around 27/0000 UTC, but the S1
(Minor) solar radiation warning remains in effect as flux values
remain elevated. The anticipated arrival of the 25 Feb CME late on
27 Feb is likely to cause an additional proton flux enhancement as
particles are accelerated ahead of the CME. No other proton events
are expected during the outlook period, barring additional
significant flare activity.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be normal to moderate on 27-28 Feb, and 14-25 Mar. High
flux levels are likely on 01-13 Mar following enhanced solar wind
conditions and elevated geomagnetic field activity.

Geomagnetic field activity is likely to reach G3 (Strong) storm
levels on 27 Feb, and G2 (Moderate) storm levels on 28 Feb, due to a combination of negative polarity CH HSS influence and the
anticipated arrival of the 25 Feb CME. G1 (Minor) storms are likely
on 06 Mar due to recurrent negative polarity CH HSS influence.
Active conditions are likely on 01, 05, 07, 15, and 25 Mar due to
multiple, recurrent CH HSSs. Quiet and quiet to unsettled conditions
are expected to prevail throughout the remainder of the outlook
period.


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