Viewing archive of Monday, 20 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 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 264 Issued at 2200Z on 20 Sep 2004IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar Activity was low. Region 672 (N05W71) produced
two C-class flares. The first was a C1.7 at 20/0310Z. The second
was a C2.1 at 20/0721Z. Region 672 has shown little change over the
past 24 hours as it approaches the west limb. Region 673 (S13E09)
decayed some this period and exhibited no significant activity. New
Region 674 (S10W23) was numbered.
IB. Solar Activity Forecast
Solar Activity is expected to be very
low to low with a slight chance for an isolated M-class flare from
Region 672 as it rotates around the west limb.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field ranged from quiet to unsettled levels with an
isolated active period from 0600-0900Z. The active level followed a
period of southward IMF Bz. The greater than 10 MeV proton event
that began yesterday, has ended. The start time was 19/1925Z and the
maximum of 57 pfu occurred at 20/0100Z. The event ended at 20/1205Z.
The greater than 2 MeV electron flux at geosynchronous orbit
briefly reached high levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be quiet to unsettled with isolated high latitude active
periods on 21 September. Active to minor storm levels are expected
on 22 September due to a CME associated with the M1.9 flare on 19
September. Predominantly unsettled to active conditions are expected
on 23 September.
III. Event Probabilities 21 Sep to 23 Sep
| Class M | 10% | 05% | 05% |
| Class X | 01% | 01% | 01% |
| Proton | 05% | 10% | 05% |
| PCAF | yellow | ||
IV. Penticton 10.7 cm Flux
Observed 20 Sep 101 Predicted 21 Sep-23 Sep 095/090/090 90 Day Mean 20 Sep 112
V. Geomagnetic A Indices
Observed Afr/Ap 19 Sep 004/005 Estimated Afr/Ap 20 Sep 012/015 Predicted Afr/Ap 21 Sep-23 Sep 012/015-020/025-010/015
VI. Geomagnetic Activity Probabilities 21 Sep to 23 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 40% | 35% |
| Minor storm | 10% | 25% | 15% |
| Major-severe storm | 01% | 10% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 30% | 50% | 40% |
| Minor storm | 15% | 30% | 20% |
| Major-severe storm | 05% | 15% | 10% |
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