Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 140 Issued at 2200Z on 20 May 2023
IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity has been at high levels for the past 24 hours. The largest solar event of the period was a M8 event observed at 20/1235Z from Region 3311 (N18E47). There are currently 8 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is expected to be moderate with a chance for X-class flares on days one, two, and three (21 May, 22 May, 23 May).
IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at unsettled to major storm levels for the past 24 hours. Solar wind speed reached a peak of 607 km/s at 20/2018Z. Total IMF reached 20 nT at 20/0323Z. The maximum southward component of Bz reached -17 nT at 20/0900Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 146 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and two (21 May, 22 May) and quiet to minor storm levels on day three (23 May). Protons have a slight chance of crossing threshold on days one, two, and three (21 May, 22 May, 23 May).
III. Event probabilities 21 May-23 May
Class M 75/75/75
Class X 35/35/35
Proton 15/15/15
PCAF green
IV. Penticton 10.7 cm Flux
Observed 20 May 170
Predicted 21 May-23 May 168/160/155
90 Day Mean 20 May 153
V. Geomagnetic A Indices
Observed Afr/Ap 19 May 010/008
Estimated Afr/Ap 20 May 024/034
Predicted Afr/Ap 21 May-23 May 010/012-011/012-014/018
VI. Geomagnetic Activity Probabilities 21 May-23 May
A. Middle Latitudes
Active 30/30/35
Minor Storm 10/15/20
Major-severe storm 01/01/05
B. High Latitudes
Active 15/20/15
Minor Storm 30/25/20
Major-severe storm 40/25/20
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