Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 27 August 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 239 Issued at 2200Z on 27 Aug 2021

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 C3 event observed at 26/2322Z from Region 2860 (S30E14). There are currently 4 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be low with a slight chance for an M-class flare on days one, two, and three (28 Aug, 29 Aug, 30 Aug).

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 525 km/s at 27/1906Z. Total IMF reached 16 nT at 27/1315Z. The maximum southward component of Bz reached -15 nT at 27/1847Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 161 pfu.

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

III. Event probabilities 28 Aug-30 Aug
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 27 Aug 090
Predicted 28 Aug-30 Aug 090/090/090
90 Day Mean 27 Aug 079

V. Geomagnetic A Indices
Observed Afr/Ap 26 Aug 006/006
Estimated Afr/Ap 27 Aug 018/022
Predicted Afr/Ap 28 Aug-30 Aug 012/015-011/018-022/025

VI. Geomagnetic Activity Probabilities 28 Aug-30 Aug
A. Middle Latitudes
Active 40/35/30
Minor Storm 25/35/40
Major-severe storm 05/20/25
B. High Latitudes
Active 10/05/05
Minor Storm 20/20/15
Major-severe storm 65/75/80