Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 26 April 2013


Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 116 Issued at 2200Z on 26 Apr 2013

IA. Analysis of Solar Active Regions and Activity from 25/2100Z to
26/2100Z: Solar activity has been at low levels for the past 24 hours.
The largest solar event of the period was a C7 event observed at
26/0627Z from Region 1726 (N13W93). 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 and a slight chance for an X-class flare on
day one (27 Apr) and expected to be low with a chance for M-class flares
on days two and three (28 Apr, 29 Apr).

IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z: The geomagnetic
field has been at quiet to minor storm levels for the past 24 hours.
Solar wind speed, as measured by the ACE spacecraft, reached a peak
speed of 622 km/s at 26/1426Z. Total IMF reached 10 nT at 26/0341Z. The
maximum southward component of Bz reached -8 nT at 26/0233Z. Electrons
greater than 2 MeV at geosynchronous orbit reached a peak level of 843
pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on day one (27 Apr), and quiet levels
on days two and three (28 Apr, 29 Apr) with a slight chance for active
conditions decreasing over the next three days. Protons greater than 10
Mev have a slight chance of crossing threshold on day one (27 Apr).

III. Event probabilities 27 Apr-29 Apr
Class M 40/25/25
Class X 15/05/05
Proton 15/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 26 Apr 122
Predicted 27 Apr-29 Apr 113/119/122
90 Day Mean 26 Apr 112

V. Geomagnetic A Indices
Observed Afr/Ap 25 Apr 014/008
Estimated Afr/Ap 26 Apr 014/018
Predicted Afr/Ap 27 Apr-29 Apr 008/008-005/005-003/005

VI. Geomagnetic Activity Probabilities 27 Apr-29 Apr
A. Middle Latitudes
Active 15/10/10
Minor Storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/15/15
Major-severe storm 20/10/10

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