Joint USAF/NOAA Report of Solar and Geophysical Activity 10 September 2011

:Product: Report of Solar-Geophysical Activity
:Issued: 2011 Sep 10 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 253 Issued at 2200Z on 10 Sep 2011
IA. Analysis of Solar Active Regions and Activity from 09/2100Z
to 10/2100Z: Solar activity was moderate. A significant filament
eruption (N10W48) occurred around 10/0300Z with an associated
partial-halo CME (plane-of-sky speed of 620 km/s). Region 1283
(N13W73) produced an M1/Sn at 10/0740Z with an associated limb-event
CME. Analysis of the potential geoeffectiveness of these CMEs is on
going. Region 1283 shows penumbral growth. Region 1289 (N23E24)
produced B and C class activity, and has shown trailer spot decay.
New Region 1291 (N23W03) was numbered during the period and produced
a B-class flare.
IB. Solar Activity Forecast: Solar activity is expected to be low
to moderate during the period (11 – 13 September) with a slight
chance for another X-class flare from Region 1283 and developing
Region 1289.
IIA. Geophysical Activity Summary 09/2100Z to 10/2100Z:
The geomagnetic field was at unsettled to minor storm levels.
Activity was most likely due to continuing CME effects. ACE data
showed that Bt peaked at 20nT, Bz dipped south to -13nT, density
spiked to 16p/cc, wind speeds ranged between 382 – 553 km/s, and
temperature remained high, but decreased between 10/0330 – 1400Z.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be unsettled with a chance for active periods on day 1
(11 September) as CME effects subside, but a recurrent coronal hole
high speed stream (CH HSS) is expected to become geoeffective.
Unsettled activity is expected to continue on days 2 and 3 (12 – 13
September) under the effects of the CH HSS.
III. Event Probabilities 11 Sep-13 Sep
Class M 65/60/55
Class X 15/10/05
Proton 01/01/01
PCAF Green
IV. Penticton 10.7 cm Flux
Observed 10 Sep 116
Predicted 11 Sep-13 Sep 115/115/110
90 Day Mean 10 Sep 099
V. Geomagnetic A Indices
Observed Afr/Ap 09 Sep 013/036
Estimated Afr/Ap 10 Sep 022/030
Predicted Afr/Ap 11 Sep-13 Sep 012/015-008/008-008/008
VI. Geomagnetic Activity Probabilities 11 Sep-13 Sep
A. Middle Latitudes
Active 25/20/20
Minor storm 10/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 30/25/25
Minor storm 15/10/05
Major-severe storm 10/01/01