Joint USAF/NOAA Report of Solar and Geophysical Activity 3 September 2011
:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Sep 03 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 246 Issued at 2200Z on 03 Sep 2011
IA. Analysis of Solar Active Regions and Activity from 02/2100Z
to 03/2100Z: Solar activity was at low levels due to several C-class
events observed during the period. As it approached the west limb,
Region 1280 (N12W78) produced three C-class flares, the largest a
C2/Sf at 03/1736Z. Region 1281 (S19W10) produced a C2/Sf at
03/0756Z. Region 1282 (N23W52) indicated decay in its intermediate
spots, but developed a delta magnetic structure in the large leader
spot. Two new regions were numbered during the period. New Region
1286 (N20W57) rapidly emerged as an eight spot D-type group and
produced a C1 x-ray event at 03/1846Z. New Region 1287 (S30E64)
rotated onto the disk as a three spot C-type group. All remaining
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
for the next three days (04 – 06 September) with a slight chance for
M-class activity.
IIA. Geophysical Activity Summary 02/2100Z to 03/2100Z:
The geomagnetic field was at quiet to unsettled levels with an
isolated active period observed at Boulder between 03/0900Z – 1200Z.
At about 03/0100Z, observations from the ACE spacecraft indicated an
increase in temperature, density and wind speed. These increases,
coupled with a brief period of southward Bz to -12nT and an increase
in Bt to 13nT, were indicative of a co-rotating interaction region
in advance of a coronal hole high speed stream. During the period,
wind speed increased from about 275 km/s to near 425 km/s while Bz
generally fluctuated between +/- 5 nT.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at quiet to unsettled levels, with a chance for
isolated active periods, on day one (04 September) as the coronal
hole high speed stream (CH HSS) persists. Days two and three (05 –
06 September) will see a return to mostly quiet levels as the CH HSS
moves out of a geoeffective position.
III. Event Probabilities 04 Sep-06 Sep
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 03 Sep 119
Predicted 04 Sep-06 Sep 120/120/115
90 Day Mean 03 Sep 097
V. Geomagnetic A Indices
Observed Afr/Ap 02 Sep 001/003
Estimated Afr/Ap 03 Sep 011/011
Predicted Afr/Ap 04 Sep-06 Sep 008/008-005/005-005/005
VI. Geomagnetic Activity Probabilities 04 Sep-06 Sep
A. Middle Latitudes
Active 20/15/10
Minor storm 05/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 25/20/15
Minor storm 10/05/01
Major-severe storm 01/01/01
