Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 27 September 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 270 Issued at 2200Z on 27 Sep 2017

IA.  Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: 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 27/0101Z from Region 2683 (N13E46). 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 on days one, two, and three (28 Sep, 29 Sep, 30 Sep).

IIA.  Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to major storm levels for the past 24 hours. Solar wind speed reached a peak of 714 km/s at 27/2040Z. Total IMF reached 17 nT at 27/0640Z. The maximum southward component of Bz reached -16 nT at 27/0640Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 126 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at active to major storm levels on day one (28 Sep), unsettled to minor storm levels on day two (29 Sep) and quiet to active levels on day three (30 Sep).

III.  Event probabilities 28 Sep-30 Sep
Class M    01/01/01
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           27 Sep 091
Predicted   28 Sep-30 Sep 091/091/091
90 Day Mean        27 Sep 082

V.  Geomagnetic A Indices
Observed Afr/Ap 26 Sep  003/004
Estimated Afr/Ap 27 Sep  022/030
Predicted Afr/Ap 28 Sep-30 Sep  024/032-020/026-011/014

VI.  Geomagnetic Activity Probabilities 28 Sep-30 Sep
A.  Middle Latitudes
Active                35/35/25
Minor Storm           40/30/10
Major-severe storm    10/05/01
B.  High Latitudes
Active                05/10/15
Minor Storm           20/20/25
Major-severe storm    80/60/40