:Product: 20040919RSGA.txt
:Issued: 2004 Sep 19 2200 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 263 Issued at 2200Z on 19 Sep 2004
IA.  Analysis of Solar Active Regions and Activity from  18/2100Z
to 19/2100Z:  Solar activity was moderate. Region 672 (N05W58), which
has been in a decay phase over the last 72 hours, produced two
notable events this period. The first was an extended C3.8 flare at
19/1148Z that erupted along a filament channel just north of the
spot cluster.  The second was an M1.9 flare at 19/1712Z. This
impressive flare had associated Type II (604 km/s) and Type IV radio
sweeps; a 520 sfu Tenflare, and a greater than 10 MeV proton event.
LASCO imagery was unavailable. Region 672 is a C-type beta spot
group with under 100 millionths of white light area coverage. Region
673 (S13E22) showed little change this period and continues to
produce occasional B-class flare activity.
IB.  Solar Activity Forecast:  Solar activity is expected to be low
to very low. There is a small chance of another M-class flare from
Region 672 before it rotates around the west limb early on 22
September. Occasional C-class flares are possible from Region 673.
IIA.  Geophysical Activity Summary 18/2100Z to 19/2100Z:
The geomagnetic field was quiet. Solar wind speed was generally below
400 km/s. A greater than 10 MeV proton event followed today's M1
flare at 19/1712Z. The proton event began at 19/1925Z and was still
in progress at the time of issue. The maximum flux value so far was
35 pfu at 19/2025Z. A greater than 100 MeV proton flux enhancement
was also observed, but has not exceeded the 1 pfu event threshold.
The greater than 2 MeV electron flux at geosynchronous orbit was at
high levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to remain at mostly quiet to unsettled levels on 20 and 21
September. A disturbance associated with today's M1 flare and CME is
expected to occur on 22 September: Active to minor storm periods are
likely. The greater than 10 MeV proton event in progress now is
expected to end by 21 September.
III.  Event Probabilities 20 Sep-22 Sep
Class M    15/10/10
Class X    01/01/01
Proton     99/10/10
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           19 Sep 105
Predicted   20 Sep-22 Sep  100/095/090
90 Day Mean        19 Sep 112
V.  Geomagnetic A Indices
Observed Afr/Ap 18 Sep  016/016
Estimated Afr/Ap 19 Sep  005/008
Predicted Afr/Ap 20 Sep-22 Sep  005/008-008/012-015/020
VI.  Geomagnetic Activity Probabilities 20 Sep-22 Sep
A.  Middle Latitudes
Active                15/20/30
Minor storm           01/05/10
Major-severe storm    01/01/05
B.  High Latitudes
Active                20/25/40
Minor storm           05/10/20
Major-severe storm    01/01/10