Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 23 April 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 113 Issued at 2200Z on 23 Apr 2013

IA. Analysis of Solar Active Regions and Activity from 22/2100Z to
23/2100Z: 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
23/1414Z from Region 1726 (N13W49). There are currently 5 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 (24 Apr, 25 Apr, 26 Apr).

IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z: The geomagnetic
field has been at quiet levels for the past 24 hours. Solar wind speed,
as measured by the ACE spacecraft, reached a peak speed of 352 km/s at
23/1951Z. Total IMF reached 11 nT at 23/1521Z. The maximum southward
component of Bz reached -9 nT at 23/1900Z.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on days one and three (24 Apr, 26 Apr)
and unsettled to minor storm levels on day two (25 Apr). Protons have a
slight chance of crossing threshold on days one, two, and three (24 Apr,
25 Apr, 26 Apr).

III. Event probabilities 24 Apr-26 Apr
Class M 40/40/40
Class X 15/15/15
Proton 15/15/15
PCAF green

IV. Penticton 10.7 cm Flux
Observed 23 Apr 118
Predicted 24 Apr-26 Apr 115/115/115
90 Day Mean 23 Apr 111

V. Geomagnetic A Indices
Observed Afr/Ap 22 Apr 005/004
Estimated Afr/Ap 23 Apr 007/007
Predicted Afr/Ap 24 Apr-26 Apr 011/008-016/012-011/018

VI. Geomagnetic Activity Probabilities 24 Apr-26 Apr
A. Middle Latitudes
Active 15/25/15
Minor Storm 05/10/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/25/25
Major-severe storm 25/35/25