Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 18 August 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 230 Issued at 2200Z on 18 Aug 2021

IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 1 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 (19 Aug, 20 Aug, 21 Aug).

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 476 km/s at 17/2108Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 490 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on days one and two (19 Aug, 20 Aug) and quiet to unsettled levels on day three (21 Aug).

III. Event probabilities 19 Aug-21 Aug
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 18 Aug 075
Predicted 19 Aug-21 Aug 075/075/073
90 Day Mean 18 Aug 079

V. Geomagnetic A Indices
Observed Afr/Ap 17 Aug 007/004
Estimated Afr/Ap 18 Aug 005/006
Predicted Afr/Ap 19 Aug-21 Aug 005/005-005/005-008/008

VI. Geomagnetic Activity Probabilities 19 Aug-21 Aug
A. Middle Latitudes
Active 10/10/20
Minor Storm 01/01/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/20/30
Major-severe storm 15/15/25