Joint USAF/NOAA Report of Solar and Geophysical Activity 31 August 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Aug 31 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 243 Issued at 2200Z on 31 Aug 2011
IA. Analysis of Solar Active Regions and Activity from 30/2100Z
to 31/2100Z: Solar activity was low. Regions 1281 (S20E28) and 1283
(N12E61) each produced a single C-class flare, the largest of which
was a C5/1f at 30/2246Z from Region 1281. Regions 1281 and 1282
(N25w13) each showed intermediate and trailer spot growth during the
period. No significant changes were noted in Region 1283, though
analysis was hampered due to limb proximity. New Region 1285
(N29W48), a small Axx group, was numbered. There were no
Earth-directed CMEs observed during the period.
IB. Solar Activity Forecast: Solar activity is expected to be low
through the period (01 – 03 September) with a slight chance for an
M-class flare.
IIA. Geophysical Activity Summary 30/2100Z to 31/2100Z:
Geomagnetic field activity was at quiet levels.
IIB. Geophysical Activity Forecast: Geomagnetic field activity is
expected to be at quiet levels during days 1 – 2 (01 – 02
September). Activity is expected to increase to quiet to unsettled
levels on day 3 (03 September), with a chance for active levels, due
to a recurrent coronal hole high-speed stream.
III. Event Probabilities 01 Sep-03 Sep
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 31 Aug 109
Predicted 01 Sep-03 Sep 110/110/105
90 Day Mean 31 Aug 097
V. Geomagnetic A Indices
Observed Afr/Ap 30 Aug 002/004
Estimated Afr/Ap 31 Aug 002/005
Predicted Afr/Ap 01 Sep-03 Sep 005/005-005/005-008/008
VI. Geomagnetic Activity Probabilities 01 Sep-03 Sep
A. Middle Latitudes
Active 10/10/20
Minor storm 01/01/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/25
Minor storm 01/01/10
Major-severe storm 01/01/01