Viewing archive of Tuesday, 18 September 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Sep 18 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 261 Issued at 2200Z on 18 Sep 2001

IA. Analysis of Solar Active Regions and Activity from 17-2100Z to 18-2100Z

Solar activity remained at high levels due to the number of M-class flares. Six M1-level flares were observed over the past 24 hours, occurring in Regions 9608 (S30W84), 9616 (S13W11), 9620 (N12E44), and new Region 9628 (S17E79). Region 9608 has rotated out of view beyond the west limb. The largest sunspot groups currently on the disk are 9616 and 9628. New Regions 9625 (S30W12), 9626 (N25E47), and 9627 (N05E73) were also numbered.
IB. Solar Activity Forecast
Solar activity is expected to be moderate to high. Additional M-class flares are possible in Regions 9616, 9620, and 9628. Another major flare in Region 9608 from beyond the west limb is not out of the question.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
The geomagnetic field ranged from quiet to active. Solar wind information from the NASA ACE spacecraft exhibited increased variability including higher IMF field intensity and southward Bz.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be quiet to unsettled with occasional active periods. Increased activity is possible from a number of CME events and a possible high-speed coronal hole stream.
III. Event Probabilities 19 Sep to 21 Sep
Class M80%80%80%
Class X10%05%05%
IV. Penticton 10.7 cm Flux
  Observed       18 Sep 204
  Predicted   19 Sep-21 Sep  205/200/195
  90 Day Mean        18 Sep 165
V. Geomagnetic A Indices
  Observed Afr/Ap 17 Sep  006/010
  Estimated     Afr/Ap 18 Sep  008/010
  Predicted    Afr/Ap 19 Sep-21 Sep  015/020-012/015-010/010
VI. Geomagnetic Activity Probabilities 19 Sep to 21 Sep
A. Middle Latitudes
Minor storm10%10%05%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm15%15%10%
Major-severe storm05%01%01%

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