:Product: 20020520RSGA.txt
:Issued: 2002 May 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 140 Issued at 2200Z on 20 May 2002
IA.  Analysis of Solar Active Regions and Activity from  19/2100Z
to 20/2100Z:  Solar activity was high. Region 9961 (S22E62) produced
two M-class flares and one X-class flare during the past 24 hours.
The X-flare was an X2/2n at 1527 UTC and was impulsive. Nonetheless
this flare was associated with a narrow-width CME from the southeast
limb. The first M-flare was an M4 at 1029 UTC and the second was an
M5 at 1053 UTC. Both of these events were impulsive and were
attributed to 9961 based on SOHO/EIT data. Region 9961 appears to be
a compact, magnetically complex group which has at least a gamma
classification, and possibly a magnetic delta. Region 9957 (N09E22)
continues to be the largest group on the disk and has a delta
configuration in a compact collection of spots. A partial halo CME
was observed in C2 at 19/2026 UTC and was centered over the
southwest limb. EIT images at the same time confirmed a front-side
source from the southwest part of the disk.
IB.  Solar Activity Forecast:  Solar activity is expected to be
mostly moderate, but there is a chance for an additional major flare
event from either of Region 9961 or 9957.
IIA.  Geophysical Activity Summary 19/2100Z to 20/2100Z:
The geomagnetic field was mostly quiet to unsettled during the past
24 hours. There was an isolated active period from 1500-1800 UTC. An
interval of enhanced solar wind flow passed the ACE solar wind
spacecraft beginning at 0257 UTC and lasted about 10 hours. The Bz
magnetic field component was mostly negative with typical values
between -5 nT and -10 nT. The onset of the this flow at Earth caused
a sudden impulse at 0342 UTC, which measured 22 nT on the Boulder
magnetometer.
IIB.  Geophysical Activity Forecast:  The geomagnetic field should be
mostly unsettled tomorrow and quiet to unsettled on the second day.
Activity on the third day is expected increase slightly to unsettled
with some isolated active periods due to possible effects from
today's partial halo CME that began at 19/2026 UTC.
III.  Event Probabilities 21 May-23 May
Class M    80/80/80
Class X    20/20/20
Proton     15/15/15
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           20 May 171
Predicted   21 May-23 May  170/170/165
90 Day Mean        20 May 184
V.  Geomagnetic A Indices
Observed Afr/Ap 19 May  008/018
Estimated Afr/Ap 20 May  010/015
Predicted Afr/Ap 21 May-23 May  008/010-005/008-012/015
VI.  Geomagnetic Activity Probabilities 21 May-23 May
A.  Middle Latitudes
Active                20/20/25
Minor storm           10/10/15
Major-severe storm    05/05/10
B.  High Latitudes
Active                20/20/25
Minor storm           10/10/20
Major-severe storm    05/05/15