Subject: Weekly Highlights of Solar and Geomagnetic Activity, 10 - 16 July 2023

:Product: Weekly Highlights and Forecasts
:Issued: 2023 Jul 17 0708 UTC
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# Weekly Highlights and Forecasts
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Highlights of Solar and Geomagnetic Activity
10 - 16 July 2023

Solar activity was at moderate to high levels. Moderate levels were
observed on 10, 13-16 Jul. High levels occurred on 11-12 Jul due to
an M6.8/Sf at 11/1808 UTC from Region 3368 (S17, L=053, class/area
Dao/100 on 11 Jul), an M5.8 at 11/2215 UTC from Region 3372 (N24,
L=272, class/area Fko/770 on 14 Jul), and an M6.9/1n at 12/0855 UTC
from Region 3372. The majority of the M-class activity was produced
by Regions 3372 and 3363 (S21, L=346, class/area Dko/850 on 12 Jul).
Region 3372 produced 11 M-class flares and Region 3363 produced 3
M-flares.

Other activity included an M2.3/2n flare at 10/0355 UTC from Region
3366 (S10, L=056, class/area Dso/130 on 10 Jul) with an associated
Type II radio sweep and a partial halo CME off the SW limb first
observed in SOHO/LASCO C2 imagery at 10/0400 UTC. Another CME was
observed at 11/1924 UTC with a southward bias that was associated
with a filament eruption centered near S30E07 that began at 11/1830
UTC. WSA/ENLIL modelling of the events showed a potential arrival on
14-15 Jul.

Two more CMEs were modelled with an Earth-directed component. A C8.8
flare at 14/1844 UTC from Region 3370 (S14, L=304, class/area
Dao/050 on 11 Jul) with an associated faint, partial halo CME that
was first observed in SOHO/LASCO C2 imagery at 14/1903 UTC. Lastly,
a CME associated with an M2.9 flare at 15/0741 UTC from Region 3363
that was observed off the SW limb at 15/0737 UTC. Both of the CMEs
were modelled with an arrival on 18 Jul, however due to uncertainty
in the model run, an arrival as early as 17 Jul was likely.

There was a greater than 10 MeV proton event reaching the S1 (Minor)
levels. The event began at 16/0635 UTC, reached a maximum flux of 18
pfu at 16/0735 UTC, and ended at 16/0910 UTC.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels. The highest flux value was 933 pfu
observed at 10/1810 UTC.

Geomagnetic field activity was at nominal levels with solar wind
speed between 300-400 km/s and total field between 4-9 nT through
early on 13 Jul. The geomagnetic field was at quiet levels on 10 and
12 Jul and quiet to unsettled levels on 11 Jul. Weak shocks were
observed in ACE solar wind data at 13/1109 UTC and 13/1551 UTC.
Solar wind speed increased to around 300 km/s to near 350 km/s.
Total field increased to a maximum of 14 nT at 13/1621 UTC. The
geomagnetic field responded with quiet to unsettled levels on 13
Jul. On 14/1526 UTC, another shock occurred which increased total
field to 15 nT and eventually 18 nT. Solar wind speed increased from
388-434 km/s. These were likely arrivals of the CMEs from 10 and 11
Jul. CME activity waned through 15 Jul and background solar wind
conditions returned through most of 16 Jul. At 16/1836 UTC, another
shock was observed likely associated with the 14 Jul halo CME. Total
field increased from 7-14 nT and solar wind speed increased from
approximately 350-450 km/s. The Bz component deflected southward
initially to -12 nT. The geomagnetic field responded with quiet to
active levels on 14 Jul, quiet to unsettled levels on 15 Jul, and
quiet to G1 (Minor) storm conditions on 16 Jul.



Forecast of Solar and Geomagnetic Activity
17 July - 12 August 2023

Solar activity is expected to be at low to moderate levels on 17
Jul-12 Aug.

There is a chance for an S1 (Minor) solar radiation storm on 17-19
Jul due to potential significant flare activity from Region 3363 as
it transits around the west limb.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to reach high levels on 20 Jul-01 Aug due to recurrent CH
HSS influence.

Geomagnetic field activity is expected to be at unsettled to active
levels on 17-21 Jul with G1 (Minor) storms likely on 17-18 due to
persistent CME effects followed by CH HSS activity. Unsettled levels
are expected once again on 03-04 Aug due to recurrent CH HSS
effects.


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