Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 September 2015

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 264 Issued at 2200Z on 21 Sep 2015

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C8 event observed at 21/0518Z from Region 2420 (N10E64). There are currently 4 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 (22 Sep, 23 Sep, 24 Sep).

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed, as measured by the ACE spacecraft, reached a peak speed of 660 km/s at 21/0649Z. Total IMF reached 8 nT at 21/0824Z. The maximum southward component of Bz reached -6 nT at 20/2152Z. Protons greater than 10 MeV at geosynchronous orbit reached a peak level of 2 pfu at 20/2105Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 374 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and three (22 Sep, 24 Sep) and quiet to active levels on day two (23 Sep). Protons greater than 10 Mev have a slight chance of crossing threshold on day one (22 Sep).

III. Event probabilities 22 Sep-24 Sep
Class M 40/30/25
Class X 05/05/05
Proton 10/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Sep 103
Predicted 22 Sep-24 Sep 105/105/110
90 Day Mean 21 Sep 103

V. Geomagnetic A Indices
Observed Afr/Ap 20 Sep 032/035
Estimated Afr/Ap 21 Sep 012/013
Predicted Afr/Ap 22 Sep-24 Sep 007/010-012/012-007/008

VI. Geomagnetic Activity Probabilities 22 Sep-24 Sep
A. Middle Latitudes
Active 25/25/10
Minor Storm 05/10/01
Major-severe storm 01/01/01
B. High Latitudes
Active 20/15/20
Minor Storm 30/25/25
Major-severe storm 30/35/20