Viewing archive of Tuesday, 11 September 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Sep 11 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 254 Issued at 2200Z on 11 Sep 2001

IA. Analysis of Solar Active Regions and Activity from 10-2100Z to 11-2100Z

Solar activity has been moderate. Several M-class flares occurred during the period. Available optical imagery suggests that newly numbered Region 9616 (S12E80) rotating on to the east limb was the source of the largest event (M4/Sf at 11/2036 UTC), as well as an earlier M1 flare at 0704 UTC. An M2 flare at 11/0111 UTC appears to have emerged from Region 9608 (S27W07), which, along with Region 9610 (S14E08), also produced several lesser C-class flares during the period.
IB. Solar Activity Forecast
Solar activity is expected to be at moderate to high levels for the next three days. All regions discussed in section 1A above appear to be potential sources for isolated major flares.
IIA. Geophysical Activity Summary 10-2100Z to 11-2100Z
Geomagnetic activity was at quiet to active levels. Onset of high speed stream effects appear to have developed from about 11/1200 UTC through the end of the period.
IIB. Geophysical Activity Forecast
Geomagnetic activity is expected to be at unsettled to active conditions for the first two days of the forecast period. A combination of coronal hole high speed stream effects, and the expected arrival of an interplanetary shock from CME activity on 9 September, are anticipated to keep geomagnetic activity elevated for the next two days. Isolated minor storm conditions are possible at higher latitudes. Conditions are expected to be quiet to unsettled by day three.
III. Event Probabilities 12 Sep to 14 Sep
Class M80%80%80%
Class X15%15%15%
IV. Penticton 10.7 cm Flux
  Observed       11 Sep 250
  Predicted   12 Sep-14 Sep  245/235/235
  90 Day Mean        11 Sep 163
V. Geomagnetic A Indices
  Observed Afr/Ap 10 Sep  005/005
  Estimated     Afr/Ap 11 Sep  011/010
  Predicted    Afr/Ap 12 Sep-14 Sep  015/020-015/015-012/012
VI. Geomagnetic Activity Probabilities 12 Sep to 14 Sep
A. Middle Latitudes
Minor storm15%15%10%
Major-severe storm05%05%05%
B. High Latitudes
Minor storm20%15%10%
Major-severe storm05%05%05%

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