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

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 110 Issued at 2200Z on 20 Apr 2013

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 C1 event observed at
20/0036Z. There are currently 6 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is likely to be low with a
chance for an M-class flare on all three days (21-23 Apr).

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic
field has been at quiet levels for the past 24 hours. Solar wind speed,
as measured by the ACE spacecraft remained around 300km/s. Total IMF
reached 6 nT at 20/1925Z. The maximum southward component of Bz reached
-4 nT at 20/1039Z. Electrons greater than 2 MeV at geosynchronous orbit
reached a peak level of 116 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet levels on day one (21 Apr), quiet to unsettled levels on
day two (22 Apr) and quiet to active levels on day three (23 Apr).

III. Event probabilities 21 Apr-23 Apr
Class M 10/10/10
Class X 05/05/05
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 20 Apr 105
Predicted 21 Apr-23 Apr 105/105/105
90 Day Mean 20 Apr 111

V. Geomagnetic A Indices
Observed Afr/Ap 19 Apr 001/002
Estimated Afr/Ap 20 Apr 003/004
Predicted Afr/Ap 21 Apr-23 Apr 004/005-006/008-008/012

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