:Product: 20020420RSGA.txt
:Issued: 2002 Apr 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 110 Issued at 2200Z on 20 Apr 2002
IA.  Analysis of Solar Active Regions and Activity from  19/2100Z
to 20/2100Z:  Solar activity was low during the past 24 hours. Most
of today's activity consisted of occasional C-class flares. The
largest of these was a C4/Sf from Region 9912 at 1548 UTC. Region
9912 showed significant growth during the past 24 hours and is a
D-type sunspot region. Region 9906 (S14W79) continues to be the
largest group on the disk and is beginning to cross the west limb.
IB.  Solar Activity Forecast:  Solar activity is expected to be
mostly low, but there is a chance for an isolated M-class event
sometime during the next three days.
IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was at active to major storm levels at
mid-latitudes and was active to severe storm at high latitudes. The
peak of the magnetic storm occurred from 0000-0900 UTC in
association with strong transient solar wind flow. The level of
geomagnetic activity weakened to mostly active during the last nine
hours, consistent with the slow return of solar wind flow to nominal
levels.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be unsettled to active during the next 24 hours as the
current disturbance subsides. Conditions should be mostly unsettled
by the second day, and quiet to unsettled by the third day. There is
a possibility for enhancement of greater than 2 MeV electrons during
the next 24-36 hours due to the current high solar wind speeds.
III.  Event Probabilities 21 Apr-23 Apr
Class M    35/30/25
Class X    05/05/05
Proton     05/05/05
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           20 Apr 177
Predicted   21 Apr-23 Apr  170/170/170
90 Day Mean        20 Apr 200
V.  Geomagnetic A Indices
Observed Afr/Ap 19 Apr  036/044
Estimated Afr/Ap 20 Apr  040/060
Predicted Afr/Ap 21 Apr-23 Apr  015/020-010/010-007/008
VI.  Geomagnetic Activity Probabilities 21 Apr-23 Apr
A.  Middle Latitudes
Active                45/25/20
Minor storm           20/20/20
Major-severe storm    15/05/05
B.  High Latitudes
Active                45/30/25
Minor storm           20/20/20
Major-severe storm    20/10/10