NOAA SEC Report of Solar-Geophysical Activity 25 Apr 2001


:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Apr 25 2200 UT
# 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 115 Issued at 2200Z on 25 Apr 2001
IA.  Analysis of Solar Active Regions and Activity from  24/2100Z
to 25/2100Z:  Solar activity has been moderate. Region 9433 (N16W15)
produced two M-class flares during the period. The largest was an
M2/2n at 25/1348 UTC. This event had an associated Type II radio
sweep and a 200 sfu 10 cm radio burst. A coronal mass ejection (CME)
was also observed during this event, however images from the
LASCO/EIT space craft show it to be non earth-directed. Region 9433
continued to grow in area and spot count during the period and
retains an F-type spot group with a beta-gamma-delta magnetic
configuration. Regions 9438 (S13E22) and 9439 (S22W28) were numbered
during the period.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate to high. The ongoing development of Region 9433 suggests a
major flare is possible sometime during the forecast period.
IIA.  Geophysical Activity Summary 24/2100Z to 25/2100Z:
The geomagnetic field was quiet to unsettled.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to remain at quiet to unsettled conditions barring an
earth-directed CME. There is an increasing chance for a proton event
as Region 9433 continues to evolve and rotate into the western solar
hemisphere.
III.  Event Probabilities 26 Apr-28 Apr
Class M    80/80/80
Class X    25/25/25
Proton     20/20/20
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           25 Apr 194
Predicted   26 Apr-28 Apr  200/210/215
90 Day Mean        25 Apr 167
V.  Geomagnetic A Indices
Observed Afr/Ap 24 Apr  011/008
Estimated Afr/Ap 25 Apr  010/008
Predicted Afr/Ap 26 Apr-28 Apr  010/020-010/010-010/010
VI.  Geomagnetic Activity Probabilities 26 Apr-28 Apr
A.  Middle Latitudes
Active                10/10/10
Minor storm           05/05/05
Major-severe storm    01/01/01
B.  High Latitudes
Active                20/20/20
Minor storm           10/10/10
Major-severe storm    01/01/01

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