:Product: 20020522RSGA.txt
:Issued: 2002 May 22 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 22 May 2002
IA.  Analysis of Solar Active Regions and Activity from  21/2100Z
to 22/2100Z:  Solar activity was moderate during the past 24 hours.
An M1/2f event was produced by Region 9960 (N14E19) at 2139 UTC. The
flare was associated with a CME from the northeast limb. This event
was followed by a long duration C9/1f flare from Region 9948
(S21W84) which began at 21/2314 UTC, reached maximum at 22/0030 UTC,
and ended at 22/0128 UTC. This event was associated with a CME from
the southwest limb. Subsequent to this was another long-duration
event, a C5/Sf (maximum time at 0354) from the eruption of a long,
north-south filament just east of 9948 (near S22W53). This flare
showed classic parallel ribbons in H-alpha and was associated with a
very fast, spectacular looking full-halo CME. The plane-of-sky
velocity was estimated to be about 1500 km/s. The appearance of the
CME in the coronagraph data indicates a southwesterly direction of
the leading edge. Region 9957 (N10W04) continues to dominate the
disk in terms of area and magnetic field strengths but is decaying
and has been quiet. Region 9961 (S22E34) retains its complexity from
yesterday and is growing slowly, but was also quiet. Two new sunspot
groups were assigned today: Region 9964 (S15E08) and Region 9965
(S10E62).
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate during the next three days. The most likely sources for
M-class events are 9957, 9960 (N14E19), and 9961. There continues to
be a slight chance for a major flare or a proton producing flare.
IIA.  Geophysical Activity Summary 21/2100Z to 22/2100Z:
The geomagnetic field ranged from quiet to active levels. A weak
shock passed the ACE spacecraft at about 21/2100 UTC and produced a
sudden impulse at 21/2205 UTC which measured 27 nT on the Boulder
magnetometer. The SI was followed by an isolated active period but
conditions quickly dropped back to quiet to unsettled levels after
22/0000 UTC. An enhancement of greater than 10 MeV protons began
around 0800 UTC. Flux levels rose slowly and finally crossed event
threshold at 1755 UTC. The event remains in progress with current
levels at about 46 PFU. It is likely that these particles were
accelerated by the fast shock observed today on the southwest limb
at 0350 UTC.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be mostly unsettled with a chance for some active
periods during the next 24 hours. The fast CME from the southwest
limb associated with the erupting filament is expected to overtake
the CME from the C9 flare, and the combined transient flow is
expected to impact Earth sometime early on the 24th. Due to the
apparent direction of the event, a direct hit is not expected, but
it is likely that the eastern flank of the disturbance will impact
the Earth. Activity levels are expected to be mostly active, but
there is a chance for some isolated storm level activity. Conditions
should subside to mostly unsettled with a few active periods by the
third day. The greater than 10 MeV proton event is expected to end
sometime in the next 24 hours.
III.  Event Probabilities 23 May-25 May
Class M    55/55/55
Class X    10/10/10
Proton     99/10/10
PCAF       in progress
IV.  Penticton 10.7 cm Flux
Observed           22 May 181
Predicted   23 May-25 May  180/175/170
90 Day Mean        22 May 184
V.  Geomagnetic A Indices
Observed Afr/Ap 21 May  012/014
Estimated Afr/Ap 22 May  010/015
Predicted Afr/Ap 23 May-25 May  012/015-025/025-012/010
VI.  Geomagnetic Activity Probabilities 23 May-25 May
A.  Middle Latitudes
Active                35/45/35
Minor storm           15/25/20
Major-severe storm    10/25/10
B.  High Latitudes
Active                40/15/25
Minor storm           20/25/30
Major-severe storm    15/40/20