Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 31 May 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 151 Issued at 2200Z on 31 May 2021

IA. Analysis of Solar Active Regions and Activity from 30/2100Z to 31/2100Z: 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 on days one, two, and three (01 Jun, 02 Jun, 03 Jun).

IIA. Geophysical Activity Summary 30/2100Z to 31/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 423 km/s at 30/2250Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 176 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and two (01 Jun, 02 Jun) and quiet to unsettled levels on day three (03 Jun).

III. Event probabilities 01 Jun-03 Jun
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 31 May 082
Predicted 01 Jun-03 Jun 082/082/082
90 Day Mean 31 May 077

V. Geomagnetic A Indices
Observed Afr/Ap 30 May 007/007
Estimated Afr/Ap 31 May 005/005
Predicted Afr/Ap 01 Jun-03 Jun 015/018-014/015-007/008

VI. Geomagnetic Activity Probabilities 01 Jun-03 Jun
A. Middle Latitudes
Active 35/35/15
Minor Storm 10/10/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 30/30/25
Major-severe storm 45/45/25