Viewing archive of Sunday, 21 October 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Oct 21 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 294 Issued at 2200Z on 21 Oct 2001

IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z

Solar activity was at moderate levels. Region 9661 (N14W64) produced an M2/2n flare at 21/1136 UTC with associated discrete frequency radio bursts. Analysis in white light of this region also shows a re-emergence of the delta magnetic configuration. An optically uncorrelated M1 flare was observed at 21/0518 UTC and an associated Type II radio sweep with a shock velocity of 536 km/s. Using SXI imagery it would appear that this flare had occurred in Region 9670 (S18E06). Several C-class flares were produced from Region 9674 (S09E07) during the period.
IB. Solar Activity Forecast
Solar activity is expected to be at moderate to high levels. Regions 9661 and 9670 remain capable of producing M-class or isolated major flares.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
The geomagnetic field ranged from quiet to major storm levels. A strong shock was observed at ACE at 21/1614 UTC. This was followed by a sudden impulse at 21/1645 UTC (measured as 15 nt on the Boulder magnetometer). The sudden impulse was followed by minor (21/1500-1800 UTC) and major (21/1800-2100 UTC) storm levels. BZ was predominantly negative since the arrival of shock up until the time of issue of this bulletin.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at active to major storm levels. The full halo CME from the X1/2b flare that occurred at 19/1630 UTC from Region 9661 is expected to arrive on the middle of day one of the forecast period.
III. Event Probabilities 22 Oct to 24 Oct
Class M 75%75%60%
Class X 15%15%10%
IV. Penticton 10.7 cm Flux
  Observed       21 Oct 224
  Predicted    22 Oct-24 Oct  225/225/215
  90 Day Mean        21 Oct 191
V. Geomagnetic A Indices
  Observed Afr/Ap 20 Oct  008/010
  Estimated     Afr/Ap 21 Oct  025/030
  Predicted     Afr/Ap 22 Oct-24 Oct  030/035-015/020-012/015
VI. Geomagnetic Activity Probabilities 22 Oct to 24 Oct
A. Middle Latitudes
Minor storm 40%15%01%
Major-severe storm 15%05%01%
B. High Latitudes
Minor storm 50%30%10%
Major-severe storm 20%05%01%

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