:Product: 20040521RSGA.txt
:Issued: 2004 May 21 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 142 Issued at 2200Z on 21 May 2004
IA.  Analysis of Solar Active Regions and Activity from  20/2100Z
to 21/2100Z:  Solar activity was low during the past 24 hours due to
two C-class flares: a C2 at 0551 UTC from Region 618 (S11E55) and a
C2 at 1623 UTC from Region 617 (S11W46). Region 618 has shown a slow
growth trend and Region 617 appears to be decaying. The remainder of
the solar disk and limbs were quiet and stable.
IB.  Solar Activity Forecast:  Solar activity is expected to continue
at low levels for the next three days (21-23 May). Region 618 is
expected to be the main source for activity.
IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z:
The geomagnetic field was quiet to unsettled during the past 24 hours
The solar wind speed remains somewhat elevated: there was a slow
declining trend up until 1800 UTC, after which speeds increased
again, with values around 500 km/s by forecast issue time.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be mostly unsettled with a chance for isolated active
periods at high latitudes for the next 24 hours (22 May). Unsettled
conditions should prevail for the second day (23 May) and conditions
should decline to quiet to unsettled by the third day (24 May).
III.  Event Probabilities 22 May-24 May
Class M    15/15/15
Class X    01/01/01
Proton     01/01/01
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           21 May 107
Predicted   22 May-24 May  105/105/100
90 Day Mean        21 May 105
V.  Geomagnetic A Indices
Observed Afr/Ap 20 May  011/013
Estimated Afr/Ap 21 May  012/010
Predicted Afr/Ap 22 May-24 May  010/015-010/012-005/008
VI.  Geomagnetic Activity Probabilities 22 May-24 May
A.  Middle Latitudes
Active                30/25/20
Minor storm           15/15/10
Major-severe storm    05/05/05
B.  High Latitudes
Active                30/30/15
Minor storm           20/20/10
Major-severe storm    15/15/05