Subject: Weekly Highlights of Solar and Geomagnetic Activity, 12 - 18 June 2023

:Product: Weekly Highlights and Forecasts
:Issued: 2023 Jun 19 0506 UTC
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# Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
12 - 18 June 2023

Solar activity was at low to moderate levels. Moderate levels were
observed on 16 and 18 Jun. M1 flares were observed at 16/0530 UTC
from Region 3337 (N17, L=263, class/area Axx/010 on 16 Jun), 16/1038
UTC from Region 3338 (N11, L=263, class/area Cso/140 on 16 Jun),
16/1959 UTC from Region 3331 (S22, L=017, class/area Eso/180 on 09
Jun), and 18/0031 UTC from Region 3336 (S20, L=281, class/area
Cso/160 on 14 Jun). An M2.5/2n flare was also observed from Region
3336 at 18/1353 UTC. Activity from Region 3336 was likely due to its
proximity to Region 3335 (S15, L=284, class/area Eki/390 on 17 Jun).
A type II radio sweep (440 km/s) and a narrow CME directed off the
SE limb at 18/1408 UTC was associated with the M2 flare. Although
unlikely to have much of an Earth-directed component, initial
WSA/ENLIL runs determined a possible grazing late on 21 Jun. Other
activity included a large filament eruption centered near N22W50
that began lifting off at 17/1844 UTC. Coronagraph imagery depicted
an associated CME off the NW limb beginning at 18/0125 UTC.
Modelling of the event showed a miss, however a glancing blow on
21-22 Jun cannot be ruled out.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels on 17-18 Jun with a peak flux of 3,840 pfu at 18/1430
UTC due to CH HSS influence.

Geomagnetic field activity ranged from quiet to G2 (Moderate) storm
levels. The period began with slightly enhanced solar wind speeds in
the 430-485 km/s range and total field around 6-8 nT. Nominal levels
returned on 14 Jun. The geomagnetic field responded with quiet to
unsettled levels on 12 and 14 Jun and quiet levels on 13 Jun. After
15/0800 UTC, total field began to rise followed by an increase in
solar wind speed and a change in phi angle as a CIR and negative
polarity CH HSS was becoming geoeffective. Solar wind speed reached
a maximum of 742 km/s at 16/1215 UTC and the Bz component reached a
maximum of -13 nT at 15/1655 UTC. The geomagnetic field responded
with quiet to G2 storming on 15 Jun and Unsettled to G2 storming on
16 Jun. By 17 Jun, solar wind speeds were slowly diminishing and
reached background levels on 18 Jun. Quiet to unsettled levels were
observed on those days.

Forecast of Solar and Geomagnetic Activity
19 June - 15 July 2023

Solar activity is expected to be at low to moderate levels
throughout the forecast period (19 Jun-15 Jul).

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
likely to reach high levels on 19-24 Jun and again on 14-15 Jul due
to HSS influence.

Geomagnetic field activity is expected to reach unsettled to active
levels on 19-21 Jun, 27-28 Jun, 01-02 Jul, 08 Jul, and 12-15 Jul
with G1-G2 (Minor-Moderate) levels likely on 12-13 Jul due to
recurrent CH HSS effects. There is a chance for CME effects on 21-22
Jun related to the CME eruptions on 17 and 18 Jun.


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