Viewing archive of Friday, 20 April 2012

Solar activity report

Report of Solar-Geophysical Activity 2012 Apr 20 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 111 Issued at 2200Z on 20 Apr 2012

IA. 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 M30%30%30%
Class X01%01%01%
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
Minor storm10%05%05%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm15%10%10%
Major-severe storm05%01%01%

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