Viewing archive of Wednesday, 20 April 2005
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 2005 Apr 20 2210 UTC# Prepared jointly by the U.S. Dept. of Commerce, NOAA, #Space Environment Center and the U.S. Air Force. #
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 110 Issued at 2200Z on 20 Apr 2005IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar activity was very low. Region 755 (S12E37)
produced a B 8 flare at 19/2217 UTC with an associated Type II radio
sweep (estimated speed of 1128 km/s) and a CME with an estimated
speed of 776 km/s. The CME was directed to the east and is not
expected to be geoeffective. No new regions were numbered today.
IB. Solar Activity Forecast
Solar activity is expected to be very
low with a slight chance for an isolated C-flare.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was at quiet to minor storm levels. Heightened
activity was due to a solar sector boundary followed by the onset of
a coronal hole high speed stream. Solar wind speed at ACE increased
from approximately 350 km/s to 600 km/s. By the end of the period,
solar wind speed had decreased to approximately 450 km/s.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be quiet to unsettled with isolated active conditions
possible on 21 April. On 22 April, conditions are expected to
increase to unsettled to active with minor storm periods possible as
another coronal hole high speed stream is expected to become
geoeffective. On 23 April, unsettled to active conditions are
expected.
III. Event Probabilities 21 Apr to 23 Apr
| Class M | 01% | 01% | 01% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 20 Apr 077 Predicted 21 Apr-23 Apr 080/080/080 90 Day Mean 20 Apr 091
V. Geomagnetic A Indices
Observed Afr/Ap 19 Apr 006/008 Estimated Afr/Ap 20 Apr 015/020 Predicted Afr/Ap 21 Apr-23 Apr 010/015-015/018-012/015
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 25% | 30% | 25% |
| Minor storm | 10% | 15% | 10% |
| Major-severe storm | 01% | 05% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 30% | 30% | 30% |
| Minor storm | 15% | 15% | 15% |
| Major-severe storm | 05% | 05% | 05% |
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