Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 107 Issued at 2200Z on 17 Apr 2023

IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C7 event observed at 17/0633Z from Region 3281 (S22E14). There are currently 9 numbered sunspot regions on the disk

IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares and a slight chance for an X-class flare on days one, two, and three (18 Apr, 19 Apr, 20 Apr).

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 532 km/s at 17/1637Z. Total IMF reached 9 nT at 17/1144Z. The maximum southward component of Bz reached -8 nT at 17/1144Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 141 pfu

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on days one, two, and three (18 Apr, 19 Apr, 20 Apr).

III. Event probabilities 18 Apr-20 Apr
Class M 45/45/45
Class X 10/10/10
Proton 05/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 17 Apr 167
Predicted 18 Apr-20 Apr 170/168/168
90 Day Mean 17 Apr 163

V. Geomagnetic A Indices
Observed Afr/Ap 16 Apr 004/005
Estimated Afr/Ap 17 Apr 005/005
Predicted Afr/Ap 18 Apr-20 Apr 006/005-005/005-005/005

VI. Geomagnetic Activity Probabilities 18 Apr-20 Apr
A. Middle Latitudes
Active 10/10/10
Minor Storm 05/05/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/20/20
Major-severe storm 15/15/15

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