NOAA SEC Report of Solar-Geophysical Activity 25 Sep 2001

:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Sep 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 268 Issued at 2200Z on 25 Sep 2001
IA.  Analysis of Solar Active Regions and Activity from  24/2100Z
to 25/2100Z:  Solar activity was high. Region 9628 (S18W14) produced
an M7/1n with associated Type II sweep at 0440 UTC. In addition, the
region also generated an M2/1n with Type II at 1027 UTC, and an
M1/Sf at 0148 UTC. This region was the premier flare site of the day
as Region 9632 (S19E06), the site of the X2/2b flare of 24/1038 UTC,
was unproductive. There are fifteen spotted regions visible today,
with new region 9638 (N03E61), the most recent addition.
IB.  Solar Activity Forecast:  Solar activity is expected to be
moderate to high. Both Regions 9628 and 9632 retain the potential
for additional M-class activity, and a possible isolated X-class
event.
IIA.  Geophysical Activity Summary 24/2100Z to 25/2100Z:
The geomagnetic field was quiet until the end of the interval. A
shock, presumably related to the flare/CME of 24/1038 UTC, passed
ACE at approximately 2003 UTC. A sudden impulse then occurred at
Boulder at 2025 UTC, measuring 25 nT. The field is now at active
levels. The proton events at greater than 10 and 100 MeV continue.
The tentative peak flux for the greater than 10 MeV event is 5040
pfu at 2100 UTC. The greater than 100 MeV tentative max was 31 pfu
at 0755 UTC. The Polar Cap Absorption event remains in progress.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be at major storm levels during the next 24-36 hours,
due to the effects of a shock/cme related to the X2/2b flare of
24/1038 UTC. The storm should persist through 27 September. The
current proton events are expected to continue for at least the next
24 hours.
III.  Event Probabilities 26 Sep-28 Sep
Class M    80/80/80
Class X    30/30/30
Proton     99/90/75
PCAF       in progress
IV.  Penticton 10.7 cm Flux
Observed           25 Sep 275
Predicted   26 Sep-28 Sep  270/265/260
90 Day Mean        25 Sep 169
V.  Geomagnetic A Indices
Observed Afr/Ap 24 Sep  005/006
Estimated Afr/Ap 25 Sep  010/012
Predicted Afr/Ap 26 Sep-28 Sep  080/100-040/040-015/015
VI.  Geomagnetic Activity Probabilities 26 Sep-28 Sep
A.  Middle Latitudes
Active                05/10/20
Minor storm           25/50/60
Major-severe storm    65/25/15
B.  High Latitudes
Active                05/10/15
Minor storm           25/40/60
Major-severe storm    70/40/20