Viewing archive of Thursday, 26 April 2012

Solar activity report

Report of Solar-Geophysical Activity 2012 Apr 26 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 117 Issued at 2200Z on 26 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 25-2100Z to 26-2100Z

Solar activity was at low levels. Region 1460 (N15W93) and Region 1465 (S18W39) both produced C1 x-ray events at 25/2242Z and 26/1723Z respectively. Both had associated CMEs but neither are expected to be geoeffective. Three consecutive CMEs appeared on LASCO/C2 imagery at 26/0924Z, 26/1148Z, and 26/1638Z. All three were around the west limb and are not expected to be geoeffective.
IB. Solar Activity Forecast
Solar activity is expected to remain low with a slight chance for M-class activity for the next three days (27 - 29 April).
IIA. Geophysical Activity Summary 25-2100Z to 26-2100Z
The geomagnetic field started the period at minor storm levels, but fell to quiet levels and remained mostly quiet for the remainder of the period. This activity was attributed to Coronal Hole High Speed Stream (CH HSS) effects. Solar wind speeds have steadily decreased from approximately 730 km/s to approximately 560 km/s. The Bz component of the interplanetary magnetic field has remained fairly neutral with minor fluctuations between +3 and -5 nT. Overall, the total field fluctuated between +2 and +8 nT. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels throughout the period.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at quiet to unsettled levels with isolated active periods for day one (27 April) as CH HSS effects begin to wane. Days two and three (28 -29 April) are expected to be mostly quiet.
III. Event Probabilities 27 Apr to 29 Apr
Class M15%15%15%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       26 Apr 119
  Predicted   27 Apr-29 Apr  115/110/105
  90 Day Mean        26 Apr 112
V. Geomagnetic A Indices
  Observed Afr/Ap 25 Apr  018/031
  Estimated     Afr/Ap 26 Apr  013/017
  Predicted    Afr/Ap 27 Apr-29 Apr  007/010-004/005-004/005
VI. Geomagnetic Activity Probabilities 27 Apr to 29 Apr
A. Middle Latitudes
Minor storm05%01%01%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm25%15%15%
Major-severe storm25%10%10%

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