Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 26 April 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 116 Issued at 2200Z on 26 Apr 2021

IA. Analysis of Solar Active Regions and Activity from 25/2100Z to 26/2100Z: 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 26/0230Z from Region 2816 (S22W79). There are currently 3 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 and two (27 Apr, 28 Apr) and expected to be very low with a chance for a C-class flares on day three (29 Apr).

IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z: The geomagnetic field has been at quiet to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 525 km/s at 26/1829Z. Total IMF reached 7 nT at 26/0324Z. The maximum southward component of Bz reached -7 nT at 26/0219Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 351 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (27 Apr) and quiet levels on days two and three (28 Apr, 29 Apr).

III. Event probabilities 27 Apr-29 Apr
Class M 10/10/05
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 26 Apr 080
Predicted 27 Apr-29 Apr 080/078/078
90 Day Mean 26 Apr 076

V. Geomagnetic A Indices
Observed Afr/Ap 25 Apr 016/019
Estimated Afr/Ap 26 Apr 014/016
Predicted Afr/Ap 27 Apr-29 Apr 007/008-006/005-005/005

VI. Geomagnetic Activity Probabilities 27 Apr-29 Apr
A. Middle Latitudes
Active 15/10/10
Minor Storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/20/20
Major-severe storm 20/10/10