Joint USAF/NOAA Report of Solar and Geophysical Activity 1 September 2011

:Product: 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