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% |
All times in UTC
Latest news
Wednesday, 14 May 2025
Another X-flare! Potent sunspot region 4087!
Tuesday, 13 May 2025
X1.1 solar flare from sunspot region 4086
Tuesday, 15 April 2025
CME arrival, G3 storm watch
Latest forum messages
Have you ever dreamed of the sun? 46Upper atmosphere phenomena Red sprites and Blue jets 24AR 14095 2Filaments and prominences 172AR 14093 10
More topicsSupport SpaceWeatherLive.com!
A lot of people come to SpaceWeatherLive to follow the Sun's activity or if there is aurora to be seen, but with more traffic comes higher server costs. Consider a donation if you enjoy SpaceWeatherLive so we can keep the website online!
Space weather facts
| Last X-flare | 2025/05/14 | X2.7 |
| Last M-flare | 2025/05/21 | M1.2 |
| Last geomagnetic storm | 2025/05/17 | Kp6+ (G2) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| April 2025 | 140.6 +6.4 |
| May 2025 | 68.7 -72 |
| Last 30 days | 86.9 -26 |