Viewing archive of Saturday, 21 April 2012
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 2012 Apr 21 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 112 Issued at 2200Z on 21 Apr 2012IA. Analysis of Solar Active Regions and Activity from 20-2100Z to 21-2100Z
Solar activity was low. Regions 1460 (N16W27 -
Dkc/beta) and 1465 (S17E27 - Dso/beta) each produced a low-level
C-class flare. Region 1460 showed minor interior spot growth and
some mixed polarities in its trailer portion. Minor interior spot
growth also occurred in Region 1465 as well as penumbral growth in
its trailer. Region 1459 (S14W13 - Eac/beta) showed penumbral growth
in its interior portion and maintained a simple beta magnetic
configuration. No Earth-directed CMEs were observed during the
period. No new regions were numbered.
IB. Solar Activity Forecast
Solar activity is expected to be low
during the period (22 - 24 April) with a chance for an isolated
M-class flare.
IIA. Geophysical Activity Summary 20-2100Z to 21-2100Z
Geomagnetic field activity was at quiet levels until around 21/1900Z,
then increased to quiet to unsettled levels. The increase was
associated with a weak interplanetary shock (IPS) passage, detected
at ACE at around 21/1611Z, and followed by a weak geomagnetic field
response at around 21/1712Z (no Sudden Geomagnetic Impulse
observed). ACE solar wind data showed a change to mostly southward
IMF Bz following the IPS passage (maximum deflections to -8 nT) as
well as a gradual increase in IMF Bt (peaks to 9 nT). A minor
increase in wind speeds also followed the IPS passage. It is likely
the CME passage was associated with the partial-halo CME observed on
18 April.
IIB. Geophysical Activity Forecast
Geomagnetic field activity is
expected to be at quiet to unsettled levels during the period (22 -
24 April) with a chance for active levels. Weak CME-passage effects
are expected during 22 - 23 April (another CME is expected to arrive
late on 22 April). A recurrent coronal hole high-speed stream is
expected to become geoeffective on 24 April.
III. Event Probabilities 22 Apr to 24 Apr
| Class M | 30% | 30% | 30% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 21 Apr 149 Predicted 22 Apr-24 Apr 150/150/145 90 Day Mean 21 Apr 112
V. Geomagnetic A Indices
Observed Afr/Ap 20 Apr 007/008 Estimated Afr/Ap 21 Apr 006/007 Predicted Afr/Ap 22 Apr-24 Apr 011/012-010/010-010/010
VI. Geomagnetic Activity Probabilities 22 Apr to 24 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 20% | 25% |
| Minor storm | 10% | 10% | 15% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 25% | 25% | 35% |
| Minor storm | 15% | 15% | 25% |
| Major-severe storm | 05% | 05% | 10% |
All times in UTC
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