Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 18 April 2013

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 108 Issued at 2200Z on 18 Apr 2013

IA. Analysis of Solar Active Regions and Activity from 17/2100Z to
18/2100Z: Solar activity has been at low levels for the past 24 hours.
The largest solar event of the period was a C6 event observed at
18/1823Z from Region 1719 (N09W91). There are currently 5 numbered
sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is likely to be low with a
slight chance for an M-class flare on day one (19 Apr) and likely to be
low on day two (20 Apr) and expected to be very low with a chance for a
C-class flares on day three (21 Apr).

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: 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 359 km/s at
18/1408Z. Electrons greater than 2 MeV at geosynchronous orbit reached a
peak level of 126 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet levels on days one, two, and three (19 Apr, 20 Apr, 21
Apr).

III. Event probabilities 19 Apr-21 Apr
Class M 10/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 18 Apr 105
Predicted 19 Apr-21 Apr 095/090/090
90 Day Mean 18 Apr 111

V. Geomagnetic A Indices
Observed Afr/Ap 17 Apr 002/003
Estimated Afr/Ap 18 Apr 002/002
Predicted Afr/Ap 19 Apr-21 Apr 006/005-005/005-004/005

VI. Geomagnetic Activity Probabilities 19 Apr-21 Apr
A. Middle Latitudes
Active 10/10/10
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 10/10/10