<AUR>.Forecast Discussion

:Product: Forecast Discussion
:Issued: 2021 Sep 16 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Solar Activity

.24 hr Summary...
Solar activity was very low and the visible disk was spotless. No new
Earth-directed CMEs were observed in available coronagraph imagery.

Solar activity is expected to be very low 16-18 Sep.

Energetic Particles

.24 hr Summary...
The greater than 2 MeV electron flux reached moderate levels and the
greater than 10 MeV proton flux was steady at background levels.

The greater than 2 MeV electron flux is expected to be normal to
moderate on 16-18 Sep. The greater than 10 MeV proton flux is expected
to persist at background levels.

Solar Wind

.24 hr Summary...
Solar wind parameters were indicative of a slow regime. Total IMF
strength averaged near 4 nT and the Bz component underwent only weak
deviations. Solar wind speed decreased from near 400 km/s to ~315 km/s
and the phi angle was predominantly positive, but did undergo some
deviations into a negative sector.

Mostly background conditions are expected the remainder of 16 Sep. On 17
Sep, moderate enhancements in the solar wind parameters are possible
with an anticipated glancing blow from the 13 Sep CME, combined with the
likely onset of a negative polarity CH HSS. Enhanced conditions should
persist into 18 Sep as CME/CH HSS effects persist.


.24 hr Summary...
The geomagnetic field was quiet.

Mostly quiet conditions are expected the remainder of 16 Sep. By 17 Sep,
the combined effects from a negative polarity CH HSS and the possible
arrival of the 13 Sep CME could result in unsettled to active
conditions, with a chance for isolated G1 (minor) levels.