Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 22 April 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 112 Issued at 2200Z on 22 Apr 2021

IA. Analysis of Solar Active Regions and Activity from 21/2100Z to 22/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C4 event observed at 22/0921Z from Region 2817 (N18W88). 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, two, and three (23 Apr,24 Apr, 25 Apr).

IIA. Geophysical Activity Summary 21/2100Z to 22/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 489 km/s at 21/2148Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 15548 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on day one (23 Apr), quiet to unsettled levels on day two (24 Apr) and quiet to major storm levels on day three(25 Apr).

III. Event probabilities 23 Apr-25 Apr
Class M 10/10/10
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 22 Apr 084
Predicted 23 Apr-25 Apr 084/084/082
90 Day Mean 22 Apr 076

V. Geomagnetic A Indices
Observed Afr/Ap 21 Apr 007/007
Estimated Afr/Ap 22 Apr 005/005
Predicted Afr/Ap 23 Apr-25 Apr 009/010-008/008-019/025

VI. Geomagnetic Activity Probabilities 23 Apr-25 Apr
A. Middle Latitudes
Active 40/30/25
Minor Storm 15/10/40
Major-severe storm 01/01/15
B. High Latitudes
Active 10/15/05
Minor Storm 25/25/20
Major-severe storm 50/40/70