NOAA SEC Report of Solar-Geophysical Activity 28 Sep 2001

:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Sep 28 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 271 Issued at 2200Z on 28 Sep 2001
IA.  Analysis of Solar Active Regions and Activity from  27/2100Z
to 28/2100Z:  Solar activity has been moderate. There were three
M-class events observed during the past 24 hours. The first of these
was an M3/2n from Region 9636 (N14E13) at 0830 UTC, which was
associated with type II and type IV sweeps and a partial halo CME
that appeared to be centered over the east limb. The second was an
M2/1n from Region 9628 (S18W48) at 1014 UTC which was associated
with a CME that was centered over the southwest limb. The 3rd was an
M1/1f from Region 9637 (S15E18) at 1926 UTC. Regions 9628 and 9632
(S18W33) continue to dominate the disk in sunspot area and still
maintain magnetic delta configurations. 9628 is showing some growth
in the northern portion of the region. Region 9632 has been
remarkably quiet, but continues to show a strong delta along an
East-West inversion line. Region 9636 seems to be decaying slightly,
but has a fairly complicated magnetic structure (gamma magnetic
class).
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate to high. Regions 9636, 9637, 9632 and 9628 all are capable
of producing additional M-class level activity. Regions 9628 and
9632 have a fair chance for producing an isolated major flare event
sometime during the next three days.
IIA.  Geophysical Activity Summary 27/2100Z to 28/2100Z:
The geomagnetic field was quiet to unsettled during the past 24
hours. The greater than 10 MeV proton event that began at 24/1215
UTC continues in progress as the flux levels declined slowly. The
flux level at forecast issue time was 94 pfu. The greater than 2 MeV
electrons attained high levels during the past 24 hours.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be unsettled to slightly active during the next 48
hours. The influence of a favorably positioned coronal hole is
expected to increase activity levels slightly. In addition, there is
a possibility for some active conditions on the third day as the
result of a glancing blow from either of today's CME events. The
greater than 10 MeV proton event is expected to end sometime in the
next 24-36 hours.
III.  Event Probabilities 29 Sep-01 Oct
Class M    80/80/80
Class X    30/30/30
Proton     99/30/30
PCAF       in progress
IV.  Penticton 10.7 cm Flux
Observed           28 Sep 266
Predicted   29 Sep-01 Oct  260/260/255
90 Day Mean        28 Sep 174
V.  Geomagnetic A Indices
Observed Afr/Ap 27 Sep  009/010
Estimated Afr/Ap 28 Sep  013/015
Predicted Afr/Ap 29 Sep-01 Oct  015/015-015/018-020/018
VI.  Geomagnetic Activity Probabilities 29 Sep-01 Oct
A.  Middle Latitudes
Active                25/25/20
Minor storm           20/20/30
Major-severe storm    20/20/25
B.  High Latitudes
Active                30/30/25
Minor storm           25/25/35
Major-severe storm    20/20/30