Viewing archive of Tuesday, 27 July 2004

Solar activity report

Any mentioned solar flare in this report has a scaling factor applied by the Space Weather Prediction Center (SWPC). Because of the SWPC scaling factor, solar flares are reported as 42% smaller than for the science quality data. The scaling factor has been removed from our archived solar flare data to reflect the true physical units.
Report of Solar-Geophysical Activity 2004 Jul 27 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 209 Issued at 2200Z on 27 Jul 2004

IA. Analysis of Solar Active Regions and Activity from 26-2100Z to 27-2100Z

Solar activity was moderate. Region 652 (N07W62) produced three M1 flares this period. Region 652 continues to slowly decay as it approaches the west limb. It still maintains considerable size and a complex delta configuration. No other significant changes were observed on the disk or limb.
IB. Solar Activity Forecast
Solar activity is expected to be moderate. Continued M-class activity is expected from Region 652 and there is a slight chance for a major flare.
IIA. Geophysical Activity Summary 26-2100Z to 27-2100Z
The geomagnetic field ranged from unsettled to severe storming. A strong sudden impulse (SI) of 95 Nt was observed on the Boulder magnetometer at 26/2228Z. This SI followed the very fast (~31 hours) transit of the full halo CME associated with the long duration M1 flare on 25/1514Z. Solar wind speed increased from the already elevated levels near 600 km/s to over 1050 km/s. After approximately four hours of fluctuating between -15 and +15 nT, the IMF Bz rotated strong southward and ranged from -15 to -25 nT for about 15 hours. The fast solar wind speed and southward Bz combined to produce severe geomagnetic storm levels at all latitudes from 27/0000Z to 27/1500Z. Solar wind speed was still near 800 km/s by the end of the period and the disturbance had declined to minor storm levels. The greater than 10 MeV proton event that began on 25/1855Z is still in progress. A rapid, short-lived increase in the greater than 10 MeV protons to 2,090 pfu occurred with the shock passage. Protons quickly declined and were straddling the 10 pfu alert threshold by the end of the period. The greater than 2 MeV electrons at geosynchronous orbit were at high levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to range from quiet to major storm levels. The most disturbed periods are expected during the first half of day one as the current major disturbance subsides. Mostly quiet to unsettled conditions are expected on 29 - 30 July.
III. Event Probabilities 28 Jul to 30 Jul
Class M55%40%10%
Class X10%05%05%
IV. Penticton 10.7 cm Flux
  Observed       27 Jul 118
  Predicted   28 Jul-30 Jul  110/105/090
  90 Day Mean        27 Jul 106
V. Geomagnetic A Indices
  Observed Afr/Ap 26 Jul  026/031
  Estimated     Afr/Ap 27 Jul  120/180
  Predicted    Afr/Ap 28 Jul-30 Jul  020/025-010/015-008/010
VI. Geomagnetic Activity Probabilities 28 Jul to 30 Jul
A. Middle Latitudes
Minor storm25%05%05%
Major-severe storm15%01%01%
B. High Latitudes
Minor storm30%10%05%
Major-severe storm20%05%01%

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