Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 26 September 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 269 Issued at 2200Z on 26 Sep 2017

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 C1 event observed at 26/0234Z from Region 2683 (N12E60). There are currently 3 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be very low with a chance for a C-class flares and a slight chance for an M-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 levels for the past 24 hours. Solar wind speed reached a peak of 346 km/s at 25/2102Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 115 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on day one (27 Sep), active to major storm levels on day two (28 Sep) and unsettled to active levels on day three (29 Sep).

III.  Event probabilities 27 Sep-29 Sep
Class M    10/10/10
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           26 Sep 091
Predicted   27 Sep-29 Sep 091/091/091
90 Day Mean        26 Sep 082

V.  Geomagnetic A Indices
Observed Afr/Ap 25 Sep  005/005
Estimated Afr/Ap 26 Sep  006/005
Predicted Afr/Ap 27 Sep-29 Sep  017/028-024/032-020/024

VI.  Geomagnetic Activity Probabilities 27 Sep-29 Sep
A.  Middle Latitudes
Active                35/35/35
Minor Storm           30/40/30
Major-severe storm    05/10/05
B.  High Latitudes
Active                05/05/10
Minor Storm           20/20/20
Major-severe storm    65/80/60