NOAA SEC Report of Solar-Geophysical Activity 8 Apr 2001

:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Apr 08 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 098 Issued at 2200Z on 08 Apr 2001
IA.  Analysis of Solar Active Regions and Activity from  07/2100Z
to 08/2100Z:  Solar activity decreased to very low levels. Region
9415 (S21E05) produced no flares during the period, but remained
large and complex with a persistent magnetic delta structure within
its lead sunspot. The remaining regions were simply structured and
stable, including newly numbered Regions 9423 (N21E03) and 9424
(S16E34).
IB.  Solar Activity Forecast:  Solar activity is expected to be at
moderate to high levels. Region 9415 may produce a major flare
during the period.
IIA.  Geophysical Activity Summary 07/2100Z to 08/2100Z:
Geomagnetic field activity ranged from quiet to major storm levels.
Quiet to unsettled levels occurred through 08/1030 UTC. A
CME-related shock front reached the ACE spacecraft at 08/1034 UTC
followed by a sudden impulse (SI) at 08/1101 UTC (58 nT, as measured
by the Boulder magnetometer). Field activity increased to active to
major storm levels following the SI. The CME source was the X5 flare
of 06 April. The greater than 10 MeV proton flux at geosynchronous
orbit remained enhanced, but slowly decreased through the period.
IIB.  Geophysical Activity Forecast:  Active to major geomagnetic
storm conditions are expected during the first day as CME effects
continue. Unsettled conditions are expected during the remainder of
the period. There will be a chance for a proton flare from Region
9415 during the period.
III.  Event Probabilities 09 Apr-11 Apr
Class M    80/80/80
Class X    25/25/25
Proton     25/25/25
PCAF       yellow
IV.  Penticton 10.7 cm Flux
Observed           08 Apr 169
Predicted   09 Apr-11 Apr  165/165/160
90 Day Mean        08 Apr 167
V.  Geomagnetic A Indices
Observed Afr/Ap 07 Apr  017/016
Estimated Afr/Ap 08 Apr  030/040
Predicted Afr/Ap 09 Apr-11 Apr  025/030-015/015-012/012
VI.  Geomagnetic Activity Probabilities 09 Apr-11 Apr
A.  Middle Latitudes
Active                40/30/25
Minor storm           20/15/10
Major-severe storm    10/05/05
B.  High Latitudes
Active                40/35/30
Minor storm           35/20/15
Major-severe storm    15/10/05