Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 December 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 354 Issued at 2200Z on 20 Dec 2013

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to
20/2100Z: Solar activity has been at moderate levels for the past 24
hours. The largest solar event of the period was a M3 event observed at
19/2319Z from Region 1934 (S15E65). 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 (21 Dec, 22 Dec, 23 Dec).

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: 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
391 km/s at 20/0820Z. Total IMF reached 5 nT at 20/0146Z. The maximum
southward component of Bz reached -5 nT at 19/2201Z.

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

III. Event probabilities 21 Dec-23 Dec
Class M 40/40/40
Class X 10/10/10
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 20 Dec 149
Predicted 21 Dec-23 Dec 150/145/140
90 Day Mean 20 Dec 140

V. Geomagnetic A Indices
Observed Afr/Ap 19 Dec 004/004
Estimated Afr/Ap 20 Dec 006/006
Predicted Afr/Ap 21 Dec-23 Dec 005/005-005/005-005/005

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