Joint USAF/NOAA Report of Solar and Geophysical Activity 26 August 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Aug 26 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 238 Issued at 2200Z on 26 Aug 2011
IA. Analysis of Solar Active Regions and Activity from 25/2100Z
to 26/2100Z: Solar activity was at low levels. Region 1271 (N17W69)
produced two C-class events during the period, the largest a C2
x-ray event at 26/1313Z. The region continued to exhibit decay in
spot count, area and magnetic complexity. Other activity consisted
of a B9 x-ray event from Region 1279 (N13E61), observed at 26/1333Z.
New Region 1280 (N17E24) emerged on the disk as a simple bi-polar
spot group. The remainder of the regions were quiet and stable.
IB. Solar Activity Forecast: Solar activity is expected to be low
for the next three days (27 – 29 August). A slight chance for
M-class activity exists on days one and two from Region 1271 before
the region rotates around the west limb on 28 August.
IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z:
The geomagnetic field was quiet. Observations from the ACE spacecraft
indicated steady conditions with wind speeds averaging about 400
km/s.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to remain at quiet levels for day one (27 August). By day
two (28 August), activity levels are expected to increase to quiet
to unsettled, with isolated active periods, due to a geoeffective,
recurrent coronal hole high speed stream. The conditions are
expected to persist through day three (29 August).
III. Event Probabilities 27 Aug-29 Aug
Class M 10/05/01
Class X 01/01/01
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 26 Aug 105
Predicted 27 Aug-29 Aug 105/100/100
90 Day Mean 26 Aug 097
V. Geomagnetic A Indices
Observed Afr/Ap 25 Aug 004/004
Estimated Afr/Ap 26 Aug 002/004
Predicted Afr/Ap 27 Aug-29 Aug 005/005-007/010-007/008
VI. Geomagnetic Activity Probabilities 27 Aug-29 Aug
A. Middle Latitudes
Active 15/20/20
Minor storm 01/05/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/30/25
Minor storm 01/15/10
Major-severe storm 01/01/01