Report of Solar-Geophysical Activity

Issued: 2011 Sep 01 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 244 Issued at 2200Z on 01 Sep 2011

IA.  Analysis of Solar Active Regions and Activity from  31/2100Z
to 01/2100Z:  Solar activity was low. Region 1283 (N12E49) produced
two C2/Sf flares during the period, the first one at 01/1248Z and
the second one at 01/1822Z. The region exhibited trailer spot growth
and remained a beta magnetic configuration. Region 1282 (N25W26) had
intermediate spot decay between the leader and trailer, but some
growth in the leader section of the region. The remainder of the
regions were quiet and stable. No Earth-directed CMEs were detected
during the period.
IB.  Solar Activity Forecast:  Solar activity is expected to be low
through the period (02 - 04 September) with a slight chance for
M-class activity.
IIA.  Geophysical Activity Summary 31/2100Z to 01/2100Z:
The geomagnetic field was quiet. Solar wind speeds, as measured at
the ACE satellite, showed a steady decline from about 350 km/s to
end the period near 290 km/s. The Bz component of the interplanetary
magnetic field did not vary much beyond +/- 2 nT.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at quiet levels during day one (02 September).
Activity is expected to increase to quiet to unsettled levels, with
isolated active periods, on days two and three (03 - 04 September).
This increase in activity is due to a recurrent coronal hole high
speed stream that is expected to rotate into a geoeffective
position.
III.  Event Probabilities 02 Sep-04 Sep
Class M    15/15/15
Class X    01/01/01
Proton     01/01/01
PCAF       Green
IV.  Penticton 10.7 cm Flux
Observed           01 Sep 112
Predicted   02 Sep-04 Sep  110/110/110
90 Day Mean        01 Sep 097
V.  Geomagnetic A Indices
Observed Afr/Ap 31 Aug  001/002
Estimated Afr/Ap 01 Sep  002/005
Predicted Afr/Ap 02 Sep-04 Sep  005/005-008/008-008/008
VI.  Geomagnetic Activity Probabilities 02 Sep-04 Sep
A.  Middle Latitudes
Active                10/20/20
Minor storm           01/05/05
Major-severe storm    01/01/01
B.  High Latitudes
Active                15/25/25
Minor storm           01/10/10
Major-severe storm    01/01/01