Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 September 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 263 Issued at 2200Z on 20 Sep 2017

IA.  Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 2 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be very low with a slight chance for a C-class flare on days one, two, and three (21 Sep, 22 Sep, 23 Sep).

IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 533 km/s at 19/2118Z. Total IMF reached 6 nT at 20/2016Z. The maximum southward component of Bz reached -4 nT at 20/1158Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 33761 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and three (21 Sep, 23 Sep) and quiet levels on day two (22 Sep).

III.  Event probabilities 21 Sep-23 Sep
Class M    01/01/01
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           20 Sep 074
Predicted   21 Sep-23 Sep 074/073/075
90 Day Mean        20 Sep 081

V.  Geomagnetic A Indices
Observed Afr/Ap 19 Sep  006/008
Estimated Afr/Ap 20 Sep  009/011
Predicted Afr/Ap 21 Sep-23 Sep  007/008-006/005-007/008

VI.  Geomagnetic Activity Probabilities 21 Sep-23 Sep
A.  Middle Latitudes
Active                20/10/20
Minor Storm           05/01/05
Major-severe storm    01/01/01
B.  High Latitudes
Active                15/15/15
Minor Storm           30/20/25
Major-severe storm    30/20/30