Joint USAF/NOAA Report of Solar and Geophysical Activity 2 September 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Sep 02 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 245 Issued at 2200Z on 02 Sep 2011
IA. Analysis of Solar Active Regions and Activity from 01/2100Z
to 02/2100Z: Solar activity was at low levels due a to C1/Sf flare
at 02/1516Z from Region 1281 (S20E01). During the period, the region
decayed slightly in area and spot count and remained a D-type,
bi-polar spot group. Region 1283 (N13E37) produced an impulsive
B8/Sf flare at 02/0852Z. The region showed penumbral development in
the trailer spots and was classified as a D-type, bi-polar spot
group. Region 1282 (N25W40) indicated an increase in area and
longitudinal extent and was classified as an E-type, bi-polar spot
group. A CME was observed lifting off the SE limb, first seen in
SOHO LASCO/C2 imagery at 02/0748Z. A plane-of-sky speed was
estimated at 375 km/s. The source of this CME appears to have
originated from a filament channel centered near S28E42. Material
motion was first observed on SDO/AIA 193 imagery at 02/0554Z. At
this time, there does not appear to be an Earthward-directed
component.
IB. Solar Activity Forecast: Solar activity is expected to be low
through the period (03 – 05 September) with a slight chance for
M-class activity.
IIA. Geophysical Activity Summary 01/2100Z to 02/2100Z:
The geomagnetic field was quiet. Solar wind speeds, as measured at
the ACE spacecraft, were steady below 300 km/s through the period. A
phi angle change from negative (toward) to positive (away) was
observed at approximately 02/0900Z. The Bz component of the
interplanetary magnetic field was predominately negative through the
period at about -4 nT.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels, with a slight chance
for active periods, on days one and two (03 – 04 September). This
increase in activity is due to a recurrent coronal hole high speed
stream expected to rotate into a geoeffective position early on 03
September. By day three (05 September), field activity is expected
to return to mostly quiet levels.
III. Event Probabilities 03 Sep-05 Sep
Class M 10/10/10
Class X 01/01/01
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 02 Sep 115
Predicted 03 Sep-05 Sep 115/115/110
90 Day Mean 02 Sep 097
V. Geomagnetic A Indices
Observed Afr/Ap 01 Sep 001/003
Estimated Afr/Ap 02 Sep 003/005
Predicted Afr/Ap 03 Sep-05 Sep 008/008-008/008-005/005
VI. Geomagnetic Activity Probabilities 03 Sep-05 Sep
A. Middle Latitudes
Active 20/20/15
Minor storm 05/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 25/25/20
Minor storm 10/10/05
Major-severe storm 01/01/01