Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 25 April 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 115 Issued at 2200Z on 25 Apr 2013

IA. Analysis of Solar Active Regions and Activity from 24/2100Z to
25/2100Z: Solar activity has been at low levels for the past 24 hours.
The largest solar event of the period was a C5 event observed at
25/1940Z. There are currently 6 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 (26 Apr, 27 Apr,
28 Apr).
IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: The geomagnetic
field has been at quiet to unsettled levels for the past 24 hours. Solar
wind speed at ACE reached a peak of 619 km/s at 25/2014Z. Total IMF
reached 10 nT at 24/2135Z. The maximum southward component of Bz reached
-6 nT at 24/2109Z. Electrons greater than 2 MeV at geosynchronous orbit
reached a peak flux of 157 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on day one (26 Apr) and quiet levels on
days two and three (27 Apr, 28 Apr). Protons have a slight chance of
crossing threshold on days one through three (26-28 Apr).

III. Event probabilities 26 Apr-28 Apr
Class M 40/40/30
Class X 15/15/10
Proton 15/15/10
PCAF green

IV. Penticton 10.7 cm Flux
Observed 25 Apr 119
Predicted 26 Apr-28 Apr 120/120/120
90 Day Mean 25 Apr 112

V. Geomagnetic A Indices
Observed Afr/Ap 24 Apr 015/024
Estimated Afr/Ap 25 Apr 011/011
Predicted Afr/Ap 26 Apr-28 Apr 011/012-006/005-005/005

VI. Geomagnetic Activity Probabilities 26 Apr-28 Apr
A. Middle Latitudes
Active 15/10/10
Minor Storm 05/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/15/15
Major-severe storm 25/10/10