Viewing archive of Monday, 20 May 2002

Solar activity report

Report of Solar-Geophysical Activity 2002 May 20 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 140 Issued at 2200Z on 20 May 2002

IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z

Solar activity was high. Region 9961 (S22E62) produced two M-class flares and one X-class flare during the past 24 hours. The X-flare was an X2/2n at 1527 UTC and was impulsive. Nonetheless this flare was associated with a narrow-width CME from the southeast limb. The first M-flare was an M4 at 1029 UTC and the second was an M5 at 1053 UTC. Both of these events were impulsive and were attributed to 9961 based on SOHO/EIT data. Region 9961 appears to be a compact, magnetically complex group which has at least a gamma classification, and possibly a magnetic delta. Region 9957 (N09E22) continues to be the largest group on the disk and has a delta configuration in a compact collection of spots. A partial halo CME was observed in C2 at 19/2026 UTC and was centered over the southwest limb. EIT images at the same time confirmed a front-side source from the southwest part of the disk.
IB. Solar Activity Forecast
Solar activity is expected to be mostly moderate, but there is a chance for an additional major flare event from either of Region 9961 or 9957.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was mostly quiet to unsettled during the past 24 hours. There was an isolated active period from 1500-1800 UTC. An interval of enhanced solar wind flow passed the ACE solar wind spacecraft beginning at 0257 UTC and lasted about 10 hours. The Bz magnetic field component was mostly negative with typical values between -5 nT and -10 nT. The onset of the this flow at Earth caused a sudden impulse at 0342 UTC, which measured 22 nT on the Boulder magnetometer.
IIB. Geophysical Activity Forecast
The geomagnetic field should be mostly unsettled tomorrow and quiet to unsettled on the second day. Activity on the third day is expected increase slightly to unsettled with some isolated active periods due to possible effects from today's partial halo CME that began at 19/2026 UTC.
III. Event Probabilities 21 May to 23 May
Class M80%80%80%
Class X20%20%20%
IV. Penticton 10.7 cm Flux
  Observed       20 May 171
  Predicted   21 May-23 May  170/170/165
  90 Day Mean        20 May 184
V. Geomagnetic A Indices
  Observed Afr/Ap 19 May  008/018
  Estimated     Afr/Ap 20 May  010/015
  Predicted    Afr/Ap 21 May-23 May  008/010-005/008-012/015
VI. Geomagnetic Activity Probabilities 21 May to 23 May
A. Middle Latitudes
Minor storm10%10%15%
Major-severe storm05%05%10%
B. High Latitudes
Minor storm10%10%20%
Major-severe storm05%05%15%

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