- Nov 13, 2023
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 269 Issued at 2200Z on 26 Sep 2023
IA. Analysis of Solar Active Regions and Activity from 25/2100Z to 26/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C5 event observed at 26/0428Z from Region 3445 (S13W23). There are currently 10 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares and a slight chance for an X-class flare on days one, two, and three (27 Sep, 28 Sep, 29 Sep).
IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z: The geomagnetic field has been at quiet to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 532 km/s at 26/1736Z. Total IMF reached 18 nT at 25/2100Z. The maximum southward component of Bz reached -12 nT at 26/1018Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 765 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and three (27 Sep, 29 Sep) and quiet to unsettled levels on day two (28 Sep). Protons have a slight chance of crossing threshold on days one and two (27 Sep, 28 Sep) and have a slight chance of crossing threshold on day three (29 Sep).
III. Event probabilities 27 Sep-29 Sep
Class M 40/45/35
Class X 15/15/10
IV. Penticton 10.7 cm Flux
Observed 26 Sep 165
Predicted 27 Sep-29 Sep 168/168/162
90 Day Mean 26 Sep 162
V. Geomagnetic A Indices
Observed Afr/Ap 25 Sep 015/021
Estimated Afr/Ap 26 Sep 026/033
Predicted Afr/Ap 27 Sep-29 Sep 011/012-007/008-009/012
VI. Geomagnetic Activity Probabilities 27 Sep-29 Sep
A. Middle Latitudes
Minor Storm 10/05/10
Major-severe storm 01/01/01
B. High Latitudes
Minor Storm 20/20/25
Major-severe storm 30/20/30