Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 December 2015

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 354 Issued at 2200Z on 20 Dec 2015

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C4 event observed at 19/2228Z. There are currently 2 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be low with a slight chance for an M-class flare on days one, two, and three (21 Dec, 22 Dec, 23 Dec).

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at active to major storm levels for the past 24 hours. Solar wind speed, as measured by the ACE spacecraft, reached a peak speed of 536 km/s at 19/2326Z. Total IMF reached 18 nT at 20/2054Z. The maximum southward component of Bz reached -18 nT at 20/0412Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 167 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on day one (21 Dec), quiet to unsettled levels on day two (22 Dec) and quiet levels on day three (23 Dec).

III. Event probabilities 21 Dec-23 Dec
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 20 Dec 117
Predicted 21 Dec-23 Dec 120/125/125
90 Day Mean 20 Dec 109

V. Geomagnetic A Indices
Observed Afr/Ap 19 Dec 008/010
Estimated Afr/Ap 20 Dec 038/059
Predicted Afr/Ap 21 Dec-23 Dec 019/020-009/010-006/005

VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec
A. Middle Latitudes
Active 30/15/10
Minor Storm 10/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 20/20/15
Minor Storm 35/25/20
Major-severe storm 40/20/10