Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 99 Issued at 2200Z on 09 Apr 2023

IA. Analysis of Solar Active Regions and Activity from 08/2100Z to 09/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C9 event observed at 09/0608Z from Region 3272 (S21E38). 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 (10 Apr, 11 Apr, 12 Apr).

IIA. Geophysical Activity Summary 08/2100Z to 09/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 476 km/s at 08/2149Z. Total IMF reached 5 nT at 08/2150Z. The maximum southward component of Bz reached -5 nT at 08/2324Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1873 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (10 Apr, 11 Apr) and quiet to active levels on day three (12 Apr).

III. Event probabilities 10 Apr-12 Apr
Class M 25/25/25
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 09 Apr 140
Predicted 10 Apr-12 Apr 140/145/150
90 Day Mean 09 Apr 168

V. Geomagnetic A Indices
Observed Afr/Ap 08 Apr 005/004
Estimated Afr/Ap 09 Apr 006/006
Predicted Afr/Ap 10 Apr-12 Apr 008/008-009/010-010/014

VI. Geomagnetic Activity Probabilities 10 Apr-12 Apr
A. Middle Latitudes
Active 15/20/30
Minor Storm 05/05/15
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/25/30
Major-severe storm 25/30/45

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