:Product: 20040912RSGA.txt
:Issued: 2004 Sep 12 2210 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Environment Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 256 Issued at 2200Z on 12 Sep 2004
IA.  Analysis of Solar Active Regions and Activity from  11/2100Z
to 12/2100Z:  Solar activity increased to moderate levels.  Region
672 (N05E33) produced an M4/2n long duration event with multiple
flare centers that occurred at 12/0057Z and had an associated Type
IV radio sweep, a Type II radio sweep (estimated shock velocity of
800 km/s), and a Tenflare of 2400 sfu.  SOHO/LASCO imagery was
limited during the period but data indicates that a full halo CME
resulted from the M4 x-ray flare and is expected to become
geoeffective (see IIB). Region 672 underwent little change during
the period in spot area and the region retains a beta-gamma magnetic
classification.  Region 667 (S11W72) produced a M3/Sn very impulsive
event (sympathetic flare from the M4 event based on SXI and Mauna
Loa H-alpha data) at 12/0139Z that had an associated Type II radio
sweep with an estimated shock velocity of 870 km/s.  The M3 flare
also appears to have produced a CME that should merge with the
previously mentioned CME.  This region remains a magnetically simply
structured beta group.  No new regions were numbered today.
IB.  Solar Activity Forecast:  Solar activity is expected to be at
low to moderate levels.  Region 672 remains capable of producing
isolated low level M-class flares, and has a slight chance of
producing a major event.
IIA.  Geophysical Activity Summary 11/2100Z to 12/2100Z:
The geomagnetic field was at quiet levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at quiet to unsettled levels on 13 September through
much of 14 September.  Late on 14 September a shock passage from the
long duration M4 flare mentioned in IA is anticipated.  Major to
severe storming may likely occur following the onset of the shock
and dominate the first half of the period on 15 September.  Further,
a recurrent high speed coronal hole stream is also expected to
become geoeffective on 15 September and continue into 16 September. 
Levels should return to predominantly quiet to unsettled levels late
on 16 September.
III.  Event Probabilities 13 Sep-15 Sep
Class M    30/30/30
Class X    05/05/05
Proton     10/10/10
PCAF       Green
IV.  Penticton 10.7 cm Flux
Observed           12 Sep 115
Predicted   13 Sep-15 Sep  110/100/095
90 Day Mean        12 Sep 112
V.  Geomagnetic A Indices
Observed Afr/Ap 11 Sep  001/006
Estimated Afr/Ap 12 Sep  002/006
Predicted Afr/Ap 13 Sep-15 Sep  008/010-010/015-040/050
VI.  Geomagnetic Activity Probabilities 13 Sep-15 Sep
A.  Middle Latitudes
Active                15/20/40
Minor storm           05/05/30
Major-severe storm    01/01/25
B.  High Latitudes
Active                20/30/35
Minor storm           05/10/35
Major-severe storm    01/05/30