Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 August 2017

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 233 Issued at 2200Z on 21 Aug 2017

IA.  Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: 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 21/0316Z from Region 2672 (N07E61). There are currently 2 numbered sunspot regions on the disk.

IB.  Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares on days one, two, and three (22 Aug, 23 Aug, 24 Aug).

IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 770 km/s at 21/0311Z. Total IMF reached 5 nT at 21/2100Z. The maximum southward component of Bz reached -4 nT at 21/2006Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 52010 pfu.

IIB.  Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on day one (22 Aug), quiet to unsettled levels on day two (23 Aug) and quiet levels on day three (24 Aug).

III.  Event probabilities 22 Aug-24 Aug
Class M    25/25/25
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           21 Aug 087
Predicted   22 Aug-24 Aug 089/089/089
90 Day Mean        21 Aug 076

V.  Geomagnetic A Indices
Observed Afr/Ap 20 Aug  021/025
Estimated Afr/Ap 21 Aug  011/014
Predicted Afr/Ap 22 Aug-24 Aug  011/012-008/008-005/005

VI.  Geomagnetic Activity Probabilities 22 Aug-24 Aug
A.  Middle Latitudes
Active                25/10/10
Minor Storm           05/01/01
Major-severe storm    01/01/01
B.  High Latitudes
Active                15/15/15
Minor Storm           25/25/15
Major-severe storm    35/20/15