Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 24 April 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 114 Issued at 2200Z on 24 Apr 2021

IA. Analysis of Solar Active Regions and Activity from 23/2100Z to 24/2100Z: Solar activity has been at low levels for the past 24 hours.The largest solar event of the period was a C2 event observed at 23/2312Z from Region 2817 (N18, L=336). 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 (25 Apr, 26 Apr, 27 Apr).

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z: The geomagnetic field has been at quiet to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 519 km/s at 24/0459Z. Total IMFreached 11 nT at 23/2113Z. The maximum southward component of Bz reached -10 nT at 23/2118Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 4918 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to major storm levels on day one (25 Apr), quiet to active levels on day two (26 Apr) and quiet levels on day three (27 Apr).

III. Event probabilities 25 Apr-27 Apr
Class M 10/10/10
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 24 Apr 079
Predicted 25 Apr-27 Apr 079/079/078
90 Day Mean 24 Apr 076

V. Geomagnetic A Indices
Observed Afr/Ap 23 Apr 015/012
Estimated Afr/Ap 24 Apr 009/009
Predicted Afr/Ap 25 Apr-27 Apr 019/025-013/015-006/005

VI. Geomagnetic Activity Probabilities 25 Apr-27 Apr
A. Middle Latitudes
Active 35/30/10
Minor Storm 35/15/01
Major-severe storm 10/05/01
B. High Latitudes
Active 05/15/15
Minor Storm 20/30/20
Major-severe storm 75/50/10