:Product: 20040920RSGA.txt
:Issued: 2004 Sep 20 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 264 Issued at 2200Z on 20 Sep 2004
IA.  Analysis of Solar Active Regions and Activity from  19/2100Z
to 20/2100Z:  Solar Activity was low. Region 672 (N05W71) produced
two C-class flares.  The first was a C1.7 at 20/0310Z.  The second
was a C2.1 at 20/0721Z. Region 672 has shown little change over the
past 24 hours as it approaches the west limb. Region 673 (S13E09)
decayed some this period and exhibited no significant activity. New
Region 674 (S10W23) was numbered.
IB.  Solar Activity Forecast:  Solar Activity is expected to be very
low to low with a slight chance for an isolated M-class flare from
Region 672 as it rotates around the west limb.
IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field ranged from quiet to unsettled levels with an
isolated active period from 0600-0900Z. The active level followed a
period of southward IMF Bz. The greater than 10 MeV proton event
that began yesterday, has ended. The start time was 19/1925Z and the
maximum of 57 pfu occurred at 20/0100Z. The event ended at 20/1205Z.
The greater than 2 MeV electron flux at geosynchronous orbit
briefly reached high levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be quiet to unsettled with isolated high latitude active
periods on 21 September. Active to minor storm levels are expected
on 22 September due to a CME associated with the M1.9 flare on 19
September. Predominantly unsettled to active conditions are expected
on 23 September.
III.  Event Probabilities 21 Sep-23 Sep
Class M    10/05/05
Class X    01/01/01
Proton     05/10/05
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           20 Sep 101
Predicted   21 Sep-23 Sep  095/090/090
90 Day Mean        20 Sep 112
V.  Geomagnetic A Indices
Observed Afr/Ap 19 Sep  004/005
Estimated Afr/Ap 20 Sep  012/015
Predicted Afr/Ap 21 Sep-23 Sep  012/015-020/025-010/015
VI.  Geomagnetic Activity Probabilities 21 Sep-23 Sep
A.  Middle Latitudes
Active                20/40/35
Minor storm           10/25/15
Major-severe storm    01/10/05
B.  High Latitudes
Active                30/50/40
Minor storm           15/30/20
Major-severe storm    05/15/10