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

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 117 Issued at 2200Z on 27 Apr 2021

IA. Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: 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 (28 Apr, 29 Apr, 30 Apr).

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 539 km/s at 27/1942Z. Total IMF reached 5 nT at 27/0008Z. The maximum southward component of Bz reached -5 nT at 26/2355Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 541 pfu.

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

III. Event probabilities 28 Apr-30 Apr
Class M 05/05/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 27 Apr 079
Predicted 28 Apr-30 Apr 078/078/078
90 Day Mean 27 Apr 076

V. Geomagnetic A Indices
Observed Afr/Ap 26 Apr 012/014
Estimated Afr/Ap 27 Apr 008/009
Predicted Afr/Ap 28 Apr-30 Apr 006/005-005/005-008/008

VI. Geomagnetic Activity Probabilities 28 Apr-30 Apr
A. Middle Latitudes
Active 10/10/20
Minor Storm 01/01/10
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/20/25
Major-severe storm 10/10/30