Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 28 April 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 118 Issued at 2200Z on 28 Apr 2021

IA. Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 3 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be very low with a chance for a C-class flares on days one, two, and three (29 Apr, 30 Apr, 01 May).

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 490 km/s at 27/2245Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1063 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on day one (29 Apr) and quiet to unsettled levels on days two and three (30 Apr, 01 May).

III. Event probabilities 29 Apr-01 May
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 28 Apr 078
Predicted 29 Apr-01 May 078/078/075
90 Day Mean 28 Apr 076

V. Geomagnetic A Indices
Observed Afr/Ap 27 Apr 008/009
Estimated Afr/Ap 28 Apr 005/005
Predicted Afr/Ap 29 Apr-01 May 005/005-008/008-006/008

VI. Geomagnetic Activity Probabilities 29 Apr-01 May
A. Middle Latitudes
Active 10/20/30
Minor Storm 01/10/10
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/25/25
Major-severe storm 10/30/40