Report of Solar-Geophysical Activity

Issued: 2011 Sep 08 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 251 Issued at 2200Z on 08 Sep 2011

IA.  Analysis of Solar Active Regions and Activity from  07/2100Z
to 08/2100Z:  Solar activity was high. Region 1283 (N16W42) produced
two major flares. The first was an X1/3b at 07/2238Z associated with
weak Types II and IV radio sweeps, a 1300 sfu Tenflare, and a
non-Earth-directed CME. The second was an M6/1n at 08/1546Z
associated with a weak Type IV radio sweep. Region 1283 maintained a
weak delta magnetic within the northern portion of its leader spots
and showed trailer spot development during the period. Region 1289
(N21E51) also showed trailer spot development during the period. No
new regions were numbered.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate during the period (09 - 11 September) with a chance for
another X-class flare from Region 1283.
IIA.  Geophysical Activity Summary 07/2100Z to 08/2100Z:
Geomagnetic field activity was at quiet levels. The greater than 2
MeV electron flux at geosynchronous orbit reached high levels during
the period.
IIB.  Geophysical Activity Forecast:  Geomagnetic field activity is
expected to be at quiet levels until late on day 1 (09 September).
Activity is expected to increase to unsettled levels late on 09
September with a chance for active levels due to a CME arrival. A
further increase to unsettled  to active levels with a chance for
minor storm levels is expected on day 2 (10 September) as the CME
passage continues. A decrease to unsettled levels is expected on day
3 (11 September). There will be a chance for a greater than 10 MeV
proton event at geosynchronous orbit on day 1.
III.  Event Probabilities 09 Sep-11 Sep
Class M    75/70/65
Class X    25/20/15
Proton     20/15/10
PCAF       Green
IV.  Penticton 10.7 cm Flux
Observed           08 Sep 110
Predicted   09 Sep-11 Sep  105/105/100
90 Day Mean        08 Sep 099
V.  Geomagnetic A Indices
Observed Afr/Ap 07 Sep  005/006
Estimated Afr/Ap 08 Sep  004/004
Predicted Afr/Ap 09 Sep-11 Sep  010/012-020/022-012/015
VI.  Geomagnetic Activity Probabilities 09 Sep-11 Sep
A.  Middle Latitudes
Active                25/30/20
Minor storm           10/25/10
Major-severe storm    01/05/01
B.  High Latitudes
Active                30/40/30
Minor storm           15/30/15
Major-severe storm    01/10/01