Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 23 May 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 143 Issued at 2200Z on 23 May 2021

IA. Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: Solar activity has been at moderate levels for the past 24 hours. The largest solar event of the period was a M1 event observed at 22/2136Z from Region 2824 (N21E13). There are currently 2 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares on days one, two, and three (24 May, 25 May, 26 May).

IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 474 km/s at 22/2144Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 794 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on day one (24 May), quiet to minor storm levels on day two (25 May) and unsettled to major storm levels on day three (26 May).

III. Event probabilities 24 May-26 May
Class M 25/25/25
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 23 May 079
Predicted 24 May-26 May 079/079/079
90 Day Mean 23 May 076

V. Geomagnetic A Indices
Observed Afr/Ap 22 May 005/004
Estimated Afr/Ap 23 May 004/005
Predicted Afr/Ap 24 May-26 May 006/005-011/008-028/042

VI. Geomagnetic Activity Probabilities 24 May-26 May
A. Middle Latitudes
Active 10/35/40
Minor Storm 01/15/30
Major-severe storm 01/01/10
B. High Latitudes
Active 15/15/10
Minor Storm 20/30/25
Major-severe storm 10/50/65