From: Space Weather Prediction Center (NOAA)
Posted: Saturday, September 11, 2021
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 254 Issued at 2200Z on 11 Sep 2021 IA. Analysis of Solar Active Regions and Activity from 10/2100Z to 11/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C1 event observed at 11/0519Z from Region 2868 (S19W49). There are currently 5 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is expected to be low with a slight chance for an M-class flare on days one, two, and three (12 Sep, 13 Sep, 14 Sep). IIA. Geophysical Activity Summary 10/2100Z to 11/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solarwind speed reached a peak of 381 km/s at 11/0315Z. Total IMF reached 13 nT at 11/0438Z. The maximum southward component of Bz reached -10 nT at 10/2244Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 150 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (12 Sep) and quiet levels on days two and three (13 Sep, 14 Sep).
III. Event probabilities 12 Sep-14 Sep
Class M 20/20/20
Class X 05/05/05
IV. Penticton 10.7 cm Flux
Observed 11 Sep 092
Predicted 12 Sep-14 Sep 092/090/086
90 Day Mean 11 Sep 081
V. Geomagnetic A Indices
Observed Afr/Ap 10 Sep 009/007
Estimated Afr/Ap 11 Sep 006/007
Predicted Afr/Ap 12 Sep-14 Sep 008/008-006/005-006/005
VI. Geomagnetic Activity Probabilities 12 Sep-14 Sep
A. Middle Latitudes
Minor Storm 05/01/01
Major-severe storm 01/01/01
B. High Latitudes
Minor Storm 25/20/20
Major-severe storm 25/20/20
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