SWPC Forecast Discussion

This message is a product of the NOAA Space Weather Prediction Center(SWPC)

:Product: Forecast Discussion
:Issued: 2023 Sep 22 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
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Solar Activity
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.24 hr Summary...
Solar activity reached moderate levels. Region 3435 (N08E10,
Dki/beta-delta) continued to be the noisiest region on the disk,
producing an M8.7 flare at 21/1254 UTC. This AR was little changed
overall, growing slightly while maintaining its delta magnetic
configuration. Regions 3441 (N08W16, Dri/beta-gamma), 3442 (S10E39,
Csi/beta-gamma), and 3443 (N27W26, Dao/beta) all exhibited relatively
rapid growth and development as the latter two produced low-level
C-class flares. Region 3438 (N11E09, Dai/beta) produced C-class flare
activity as well, but was otherwise stable. Region 3444 (N24E37,
Bxo/beta) was numbered this period, but was otherwise unremarkable. New
spots were observed on the NE limb and also trailing just behind AR
3442, but remain unnumbered at this time as we await USAF observatory
reports.

A CME associated with the aforementioned M-class flare event was
observed in coronagraph imagery at approximately 21/1353 UTC. Analysis
and modeling of this event indicates a hit at Earth by late on 24 Sep. A
subsequent CME off the NE is being further analyzed at the time of this
summary. It appears to be associated with the long duration M1 flare
that peaked at 22/0336 UTC from AR 3435.
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.Forecast...
Solar activity is likely to be at moderate levels over 22-24 Sep with
M-class flare activity.
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Energetic Particle
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.24 hr Summary...
The greater than 2 MeV electron flux reached high levels with a peak
flux of 1,420 pfu at 21/1740 UTC and the greater than 10 MeV proton flux
was at background levels.
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.Forecast...
The greater than 2 MeV electron flux is likely to be at normal to
moderate levels 22-24 Sep. The greater than 10 MeV proton flux is
expected to remain at background levels all three days.
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Solar Wind
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.24 hr Summary...
Solar wind parameters reflected a gradual transition to a more nominal
environment. Total field averaged between 3 and 5 nT, the Bz component
was mostly +/- 4 nT, and wind speeds steadily decreased from ~430 to 400
km/s. Phi was variable between solar sectors.
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.Forecast...
An enhancement in the solar wind is likely on 22 Sep due to
anticipated onset of negative polarity CH HSS. An additional enhancement
on 23 Sep is possible due to the periphery of a passing CME that left
the Sun on 20 Sep followed by another likely enhancement with the
arrival of the CME that left the Sun on 21 Sep.
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Geospace
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.24 hr Summary...
The geomagnetic field was at quiet to unsettled levels.
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.Forecast...
The geomagnetic field is expected to be at mostly unsettled to active
levels on 22 Sep due to negative polarity CH HSS onset. G1 (Minor)
geomagnetic storming is likely 23-24 Sep due to first shock and glancing
influences from the 20 Sep CME followed by the arrival of the 21 Sep CME
by late on the 24th.
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:NWRA: File downloaded/formatted: Fri Sep 22 13:41:01 UTC 2023