Viewing archive of Friday, 20 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 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 111 Issued at 2200Z on 20 Apr 2012IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar activity was low. New Region 1465 (S17E39 -
Dao/beta) emerged early in the period and showed significant growth.
It produced occasional C-class flares including a C1/1f
parallel-ribbon flare at 20/1501Z. Regions 1459 (S16E01 - Dai/beta),
1460 (N15W15 - Dkc/beta), and 1462 (S25W46 - Dho/beta) also showed
significant growth during the period. Region 1462 produced an
isolated C-class flare as it grew. There were no Earth-directed CMEs
during the period.
IB. Solar Activity Forecast
Solar activity is expected to be low
through the period (21 - 23 April) with a chance for an isolated
M-class flare.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
Geomagnetic activity was at quiet to unsettled levels with brief
active periods at high latitudes. ACE solar wind data indicated the
minor increase in activity was due to a solar sector boundary
crossing (SSBC) at approximately 20/0700Z. The SSBC was associated
with increased IMF Bt (maximum 8 nT at 20/1059Z) and a period of
sustained southward IMF Bz (maximum deflections to -7 nT around
20/0400Z).
IIB. Geophysical Activity Forecast
Geomagnetic field activity is
expected to be at quiet levels during the first half of day 1 (21
April). Activity is forecast to increase to unsettled levels with a
chance for active levels beginning around 21/1500Z and continuing
into day 3 (23 April) due to expected glancing blows from the
partial-halo CMEs observed on 18 and 19 April. There will also be a
slight chance for minor storm levels on day 1.
III. Event Probabilities 21 Apr to 23 Apr
| Class M | 30% | 30% | 30% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 20 Apr 142 Predicted 21 Apr-23 Apr 150/150/150 90 Day Mean 20 Apr 112
V. Geomagnetic A Indices
Observed Afr/Ap 19 Apr 005/005 Estimated Afr/Ap 20 Apr 007/007 Predicted Afr/Ap 21 Apr-23 Apr 014/015-011/012-010/012
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 25% | 20% | 20% |
| Minor storm | 10% | 05% | 05% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 30% | 25% | 25% |
| Minor storm | 15% | 10% | 10% |
| Major-severe storm | 05% | 01% | 01% |
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