:Product: 20020417RSGA.txt
:Issued: 2002 Apr 17 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 107 Issued at 2200Z on 17 Apr 2002
IA.  Analysis of Solar Active Regions and Activity from  16/2100Z
to 17/2100Z:  Solar activity was moderate. Region 9906 (S14W41)
produced a long-duration M2/2n flare at 17/0824 UTC. This flare was
associated with a 3000 sfu radio burst at 2695 MHz, Type II/IV radio
sweeps, and an Earth-directed "halo" CME visible in LASCO images.
The region appears to have retained its size and complexity
following the flare. Eruptive limb activity (EPL, BSL, and flare) in
the vicinity of Region 9905 (S15W90) occurred during and after the
LDE event in 9906.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate. Additional M-class flares, possibly including a major
flare, are expected in Region 9906.
IIA.  Geophysical Activity Summary 16/2100Z to 17/2100Z:
The geomagnetic field ranged from quiet to major storm levels. A
shock was observed at the NASA ACE spacecraft at 17/1022 UTC and was
followed by an SI at ground magnetometers at 17/1109 UTC (57 nT at
Boulder). This shock is believed to be associated with the LDE
M1/CME which occurred on 15 April. A greater than 10 MeV proton
event began at 17/1530 UTC. The maximum flux observed so far was 24
pfu at 17/1540 UTC. This event is believed to be associated with the
LDE M2 discussed in Part IA.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at active to minor storm levels as the current
disturbance recovers over the next 24 hours. Another disturbance at
minor to major storm levels is expected to begin on 19 April in
response to the LDE M2/CME which occurred on 17 April. The greater
than 10 MeV proton event currently in progress is expected to end
within the next 24 hours.
III.  Event Probabilities 18 Apr-20 Apr
Class M    75/60/50
Class X    10/10/05
Proton     10/10/05
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           17 Apr 194
Predicted   18 Apr-20 Apr  190/185/180
90 Day Mean        17 Apr 201
V.  Geomagnetic A Indices
Observed Afr/Ap 16 Apr  005/010
Estimated Afr/Ap 17 Apr  035/055
Predicted Afr/Ap 18 Apr-20 Apr  020/020-040/040-020/030
VI.  Geomagnetic Activity Probabilities 18 Apr-20 Apr
A.  Middle Latitudes
Active                50/50/50
Minor storm           20/30/20
Major-severe storm    10/20/10
B.  High Latitudes
Active                60/20/60
Minor storm           25/50/25
Major-severe storm    15/30/15