Viewing archive of Saturday, 17 July 2004

Solar activity report

Report of Solar-Geophysical Activity 2004 Jul 17 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 199 Issued at 2200Z on 17 Jul 2004

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

Solar activity was at high levels. Region 649 (S10E13) continues to produce M and X-class flare activity. The largest flare of the period was an X1/1f impulsive flare that occurred at 17/0757Z. Region 649 also produced an M2/1n event at 17/1651Z. Minor radio bursts accompanied both flares. LASCO imagery shows most of the CME plasma structure directed towards the eastern solar hemisphere. Region 652 (N05E71) appears fairly ominous in white light with 750 millionths of sunspot area. This region has produced several C-class flares today and remains too close to the solar eastern limb to determine accurate magnetic structure. Region 653 (S14E71) was numbered today.
IB. Solar Activity Forecast
Solar activity is expected to be at moderate to high levels.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic field ranged from quiet to major storm levels. ACE data indicates that a shock passed the instrument at approximately 16/2100Z. This transient is believed to have been the result of the weak signature, full halo CME activity seen on 13 July. Higher latitudes experienced major storm conditions between 17/0000 and 0300Z.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at predominantly unsettled levels. There is a chance for isolated active to minor storm conditions with further transient activity resulting from the multitude of major flares seen over the past several days.
III. Event Probabilities 18 Jul to 20 Jul
Class M80%80%80%
Class X40%40%40%
IV. Penticton 10.7 cm Flux
  Observed       17 Jul 149
  Predicted   18 Jul-20 Jul  150/150/145
  90 Day Mean        17 Jul 098
V. Geomagnetic A Indices
  Observed Afr/Ap 16 Jul  008/012
  Estimated     Afr/Ap 17 Jul  024/025
  Predicted    Afr/Ap 18 Jul-20 Jul  012/015-012/015-012/015
VI. Geomagnetic Activity Probabilities 18 Jul to 20 Jul
A. Middle Latitudes
Minor storm15%15%15%
Major-severe storm10%10%10%
B. High Latitudes
Minor storm20%20%20%
Major-severe storm10%10%10%

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