:Product: 20030428RSGA.txt
:Issued: 2003 Apr 28 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 118 Issued at 2200Z on 28 Apr 2003
IA.  Analysis of Solar Active Regions and Activity from  27/2100Z
to 28/2100Z:  Solar activity decreased to low levels today.  Region
337 (S14W53) produced the largest flare of the period, a C4.4/Sf
event occurring at 28/0436Z.  There was little change to the
penumbral coverage and magnetic complexity noted during the period.
Region 338 (N18W98) has rotated beyond the west limb, although it
did manage to trigger several lesser C-class flares throughout the
day.  Region 344 (N16W14) produced the second largest flare of the
interval, a C3.3/Sf occurring at 28/1815Z.  This region maintains a
very weak delta complex and magnetically appears to be showing
slight decay.  No new regions were numbered today.
IB.  Solar Activity Forecast:  Solar activity is expected to be at
low to moderate levels.
IIA.  Geophysical Activity Summary 27/2100Z to 28/2100Z:
The geomagnetic field was at quiet to minor storm levels.  A very
weak signature from the NASA/ACE data indicate a transient may have
passed around 28/1200Z although the elevated geomagnetic conditions
are believed to be from a recurrent coronal hole.  The greater than
2 MeV electron fluxes at geosynchronous orbit have again reached
high levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at predominantly unsettled to active for days one and
two of the period as the current coronal hole begins to wane.  Minor
storm conditions may occur on day three due to the onset of another
favorably positioned recurrent coronal hole.
III.  Event Probabilities 29 Apr-01 May
Class M    40/35/35
Class X    05/01/01
Proton     01/01/01
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           28 Apr 152
Predicted   29 Apr-01 May  150/150/145
90 Day Mean        28 Apr 127
V.  Geomagnetic A Indices
Observed Afr/Ap 27 Apr  011/015
Estimated Afr/Ap 28 Apr  012/020
Predicted Afr/Ap 29 Apr-01 May  012/015-012/015-015/020
VI.  Geomagnetic Activity Probabilities 29 Apr-01 May
A.  Middle Latitudes
Active                25/25/35
Minor storm           10/10/20
Major-severe storm    05/05/10
B.  High Latitudes
Active                35/35/45
Minor storm           20/20/30
Major-severe storm    10/10/15