Viewing archive of Saturday, 18 April 2009
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 2009 Apr 18 2201 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 108 Issued at 2200Z on 18 Apr 2009IA. Analysis of Solar Active Regions and Activity from 17-2100Z to 18-2100Z Solar activity was very low. No flares were observed
during the past 24 hours. The visible disk remains spotless.
IB. Solar Activity Forecast
Solar activity is expected to be very
low.
IIA. Geophysical Activity Summary 17-2100Z to 18-2100Z
The geomagnetic field was at quiet to unsettled levels. Observations
from the ACE spacecraft show solar wind speeds gradually increased
through the period from about 400 km/s to near 550 km/s with IMF Bz
fluctuations around +/- 5nT, all due to continued effects from a
coronal hole high speed stream.
IIB. Geophysical Activity Forecast
The geomagnetic field is
expected to be mostly quiet for 19 - 20 April as the coronal hole
high speed stream will have rotated out of a geoeffective position.
Quiet to unsettled levels are expected for 21 April due to a
recurrent enhancement in solar wind velocities.
III. Event Probabilities 19 Apr to 21 Apr
| Class M | 01% | 01% | 01% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 18 Apr 070 Predicted 19 Apr-21 Apr 070/070/070 90 Day Mean 18 Apr 070
V. Geomagnetic A Indices
Observed Afr/Ap 17 Apr 004/005 Estimated Afr/Ap 18 Apr 007/007 Predicted Afr/Ap 19 Apr-21 Apr 005/005-005/005-008/010
VI. Geomagnetic Activity Probabilities 19 Apr to 21 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 05% | 05% | 15% |
| Minor storm | 01% | 01% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 05% | 05% | 20% |
| Minor storm | 01% | 01% | 05% |
| Major-severe storm | 01% | 01% | 01% |
All times in UTC
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