Viewing archive of Tuesday, 21 September 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 Sep 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 265 Issued at 2200Z on 21 Sep 2004IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z Solar activity was low. Region 672 (N04W86) produced a
C7.5 flare at 0836Z. Region 672 will rotate around the west limb on
22 September. Region 673 (S13W04), the only other sunspot group on
the visible disk, is in a slow decay phase. No new regions were
numbered.
IB. Solar Activity Forecast
Solar activity is expected to be very
low with a slight chance for C-class flares from Region 673 and 672
as it rotates around the west limb.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
The geomagnetic field was quiet to unsettled with an isolated active
period between 0300Z to 0600Z. The active conditions followed a
period of southward IMF Bz. Solar wind plasma and magnetic field
measurements indicate the presence of a weak coronal hole stream.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be quiet to active with a possibility of reaching minor
storm levels on 22 September. Active to minor storm periods are
possible on the 22nd due to a weak high speed solar wind stream and
the expected impact of a CME that occurred late on 19 September.
Levels are expected to return to quiet to unsettled with isolated
active periods on 23-24 September.
III. Event Probabilities 22 Sep to 24 Sep
| Class M | 05% | 05% | 05% |
| Class X | 01% | 01% | 01% |
| Proton | 05% | 05% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 21 Sep 095 Predicted 22 Sep-24 Sep 090/090/090 90 Day Mean 21 Sep 112
V. Geomagnetic A Indices
Observed Afr/Ap 20 Sep 008/013 Estimated Afr/Ap 21 Sep 008/010 Predicted Afr/Ap 22 Sep-24 Sep 020/025-010/015-008/010
VI. Geomagnetic Activity Probabilities 22 Sep to 24 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 35% | 30% | 20% |
| Minor storm | 15% | 10% | 05% |
| Major-severe storm | 05% | 05% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 45% | 35% | 30% |
| Minor storm | 25% | 20% | 10% |
| Major-severe storm | 10% | 10% | 01% |
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