Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 265 Issued at 2200Z on 22 Sep 2023

IA. Analysis of Solar Active Regions and Activity from 21/2100Z to 22/2100Z: 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 22/1715Z from Region 3443 (N28W40). There are currently 12 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be moderate with a slight chance for an X-class flare on days one, two, and three (23 Sep, 24 Sep, 25 Sep).

IIA. Geophysical Activity Summary 21/2100Z to 22/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 428 km/s at 22/2042Z. Total IMF reached 5 nT at 22/2006Z. The maximum southward component of Bz reached -4 nT at 22/2004Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2553 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on days one and two (23 Sep, 24 Sep) and quiet to active levels on day three (25 Sep). Protons have a slight chance of crossing threshold on days one, two, and three (23 Sep, 24 Sep, 25 Sep).

III. Event probabilities 23 Sep-25 Sep
Class M 60/60/60
Class X 15/15/15
Proton 10/10/10
PCAF green

IV. Penticton 10.7 cm Flux
Observed 22 Sep 176
Predicted 23 Sep-25 Sep 178/175/172
90 Day Mean 22 Sep 161

V. Geomagnetic A Indices
Observed Afr/Ap 21 Sep 010/014
Estimated Afr/Ap 22 Sep 007/008
Predicted Afr/Ap 23 Sep-25 Sep 013/018-018/022-013/015

VI. Geomagnetic Activity Probabilities 23 Sep-25 Sep
A. Middle Latitudes
Active 35/35/25
Minor Storm 25/20/05
Major-severe storm 05/05/01
B. High Latitudes
Active 10/15/15
Minor Storm 25/20/20
Major-severe storm 65/30/25

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