Viewing archive of Thursday, 20 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 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 141 Issued at 2200Z on 20 May 2004IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar activity was low. Newly assigned Region 618
(S10E69) produced all of today's three C-class flares. The other
sunspot regions on the disk were quiet and stable. A filament in the
northeast quadrant erupted at 0136 UTC and was associated with a CME
off the northeast solar limb. The angular width of the CME was
narrow and the transient does not appear to be directed towards
Earth.
IB. Solar Activity Forecast
Solar activity is expected to be low.
Most of the activity is expected to occur in Region 618.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was mostly quiet to unsettled. However, there
was a period of minor storm levels from 0900-1200 UTC. Solar wind
data at ACE showed a steady increase in solar wind velocity from
initial values around 380 km/s up to about 500 km/s by forecast
issue time. Elevated solar wind temperature and wave patterns in the
magnetic field data suggest that the enhancement may originate from
a coronal hole.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be mostly unsettled but with a fair chance for some
isolated active periods during the next two days (21-22 May). A
decline to quiet to unsettled is expected around mid-day on the
third day (23 May).
III. Event Probabilities 21 May to 23 May
| Class M | 15% | 15% | 15% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 20 May 105 Predicted 21 May-23 May 105/100/100 90 Day Mean 20 May 105
V. Geomagnetic A Indices
Observed Afr/Ap 19 May 006/006 Estimated Afr/Ap 20 May 015/015 Predicted Afr/Ap 21 May-23 May 012/015-012/015-010/012
VI. Geomagnetic Activity Probabilities 21 May to 23 May
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 30% | 25% |
| Minor storm | 20% | 20% | 15% |
| Major-severe storm | 10% | 10% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 35% | 35% | 30% |
| Minor storm | 20% | 20% | 10% |
| Major-severe storm | 10% | 10% | 05% |
All times in UTC
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