:Product: 0909RSGA.txt
:Issued: 2011 Sep 09 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 252 Issued at 2200Z on 09 Sep 2011
IA.  Analysis of Solar Active Regions and Activity from  08/2100Z
to 09/2100Z:  Solar activity has been moderate. Region 1283 (N17W55)
produced two M-class flares. The first was an M2/1n at 09/0611Z with
an associated Type II radio sweep (estimated velocity 717 km/sec)
and a non-geoeffective CME. The second was an M1/1f at 09/1249Z.
Region 1283 showed penumbral and trailer spot decay. Region 1289
(N22E37) developed a trailer spot with penumbra. New Region 1290
(S15E29) was numbered during the period.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate during the period (10 - 12 September) with a slight chance
for another X-class flare from Region 1283.
IIA.  Geophysical Activity Summary 08/2100Z to 09/2100Z:
Geomagnetic field activity began the period at quiet levels then
increased to active to major storm levels after 09/1245Z. An
isolated severe storm period was observed from 09/1500 - 1800Z. Two
sudden impulses (SI) were observed at 09/1243Z and 09/1250Z (16nT
and 28nT respectively, as measured by the Boulder USGS
magnetometer). At 09/1150Z, ACE data indicated an interplanetary
shock arrival preceding the Boulder SIs. Bt reached up to 25nT, Bz
dropped to -23nT, density spiked up to 35p/cc, wind speeds peaked at
602km/s, and temperature increased. Activity was due to combined
CMEs associated with 06 - 07 September major flare activity. The
greater than 2 MeV electron flux at geosynchronous orbit reached
high levels during the period.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be active on day 1 (10 September) due to continuing CME
effects. Activity is expected to decrease on day 2 (11 September) to
unsettled levels with a chance for active periods as CME effects
subside, but a recurrent coronal hole high speed stream (CH HSS)
will become geoeffective. Day 3 (12 September) unsettled activity is
expected to continue under the effects of the CH HSS. There will be
a slight chance for a greater than 10 MeV proton event at
geosynchronous orbit during the period.
III.  Event Probabilities 10 Sep-12 Sep
Class M    70/65/60
Class X    20/15/10
Proton     15/10/05
PCAF       Green
IV.  Penticton 10.7 cm Flux
Observed           09 Sep 112
Predicted   10 Sep-12 Sep  110/110/110
90 Day Mean        09 Sep 099
V.  Geomagnetic A Indices
Observed Afr/Ap 08 Sep  002/004
Estimated Afr/Ap 09 Sep  018/035
Predicted Afr/Ap 10 Sep-12 Sep  020/022-012/015-008/008
VI.  Geomagnetic Activity Probabilities 10 Sep-12 Sep
A.  Middle Latitudes
Active                30/25/20
Minor storm           25/10/05
Major-severe storm    05/01/01
B.  High Latitudes
Active                40/30/25
Minor storm           30/15/10
Major-severe storm    10/01/01