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

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 144 Issued at 2200Z on 24 May 2021

IA. Analysis of Solar Active Regions and Activity from 23/2100Z to 24/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 2 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 and a slight chance for an M-class flare on day one (25 May) and expected to be very low with a chance for a C-class flares on days two and three (26 May, 27 May).

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 404 km/s at 23/2248Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1262 pfu.

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

III. Event probabilities 25 May-27 May
Class M 10/05/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 24 May 073
Predicted 25 May-27 May 073/073/072
90 Day Mean 24 May 076

V. Geomagnetic A Indices
Observed Afr/Ap 23 May 004/004
Estimated Afr/Ap 24 May 004/004
Predicted Afr/Ap 25 May-27 May 011/018-028/048-015/022

VI. Geomagnetic Activity Probabilities 25 May-27 May
A. Middle Latitudes
Active 40/30/40
Minor Storm 25/35/25
Major-severe storm 05/25/05
B. High Latitudes
Active 10/05/10
Minor Storm 25/15/25
Major-severe storm 65/80/65