Viewing archive of Friday, 21 May 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 May 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 142 Issued at 2200Z on 21 May 2004IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z Solar activity was low during the past 24 hours due to
two C-class flares: a C2 at 0551 UTC from Region 618 (S11E55) and a
C2 at 1623 UTC from Region 617 (S11W46). Region 618 has shown a slow
growth trend and Region 617 appears to be decaying. The remainder of
the solar disk and limbs were quiet and stable.
IB. Solar Activity Forecast
Solar activity is expected to continue
at low levels for the next three days (21-23 May). Region 618 is
expected to be the main source for activity.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
The geomagnetic field was quiet to unsettled during the past 24 hours
The solar wind speed remains somewhat elevated: there was a slow
declining trend up until 1800 UTC, after which speeds increased
again, with values around 500 km/s by forecast issue time.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be mostly unsettled with a chance for isolated active
periods at high latitudes for the next 24 hours (22 May). Unsettled
conditions should prevail for the second day (23 May) and conditions
should decline to quiet to unsettled by the third day (24 May).
III. Event Probabilities 22 May to 24 May
| Class M | 15% | 15% | 15% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 21 May 107 Predicted 22 May-24 May 105/105/100 90 Day Mean 21 May 105
V. Geomagnetic A Indices
Observed Afr/Ap 20 May 011/013 Estimated Afr/Ap 21 May 012/010 Predicted Afr/Ap 22 May-24 May 010/015-010/012-005/008
VI. Geomagnetic Activity Probabilities 22 May to 24 May
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 25% | 20% |
| Minor storm | 15% | 15% | 10% |
| Major-severe storm | 05% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 30% | 30% | 15% |
| Minor storm | 20% | 20% | 10% |
| Major-severe storm | 15% | 15% | 05% |
All times in UTC
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