Viewing archive of Wednesday, 25 April 2012

Solar activity report

Report of Solar-Geophysical Activity 2012 Apr 25 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 116 Issued at 2200Z on 25 Apr 2012

IA. Analysis of Solar Active Regions and Activity from 24-2100Z to 25-2100Z

Solar activity was at low levels. Region 1459 (S16W65) produced a C1 x-ray event at 25/0224Z while Region 1460 (N15W81) produced a C3/Sf at 25/1215Z. Region 1465 (S17W26) indicated consolidation in both its leader and trailer spots. The region appeared to have lost its gamma and delta magnetic configuration, but still maintained an east to west oriented inversion line. No discernible changes were noted in the remaining regions. No Earth-directed CMEs were observed during the period.
IB. Solar Activity Forecast
Solar activity is expected to remain at low levels with a slight chance for M-class activity for the next three days (26 - 28 April).
IIA. Geophysical Activity Summary 24-2100Z to 25-2100Z
The geomagnetic field ranged from quiet to minor storm conditions with an isolated high latitude severe storm period observed during 25/0600Z - 0900Z. This activity was due to coronal hole high speed stream affects (CH HSS). Over the past 24 hours, solar wind velocities gradually increased from about 600 km/s to near 800 km/s. Total field strength (Bt) varied between 5 to 12 nT while the Bz component of the interplanetary magnetic field remained mostly south from -4 to -10 nT. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels during the period.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at quiet to active levels with isolated minor storm periods on day one (26 April) as the 23 April CME is expected to become geoeffective. Quiet to unsettled levels with isolated active periods are expected on day two (27 April) as effects of the CME wane. By day three (28 April), mostly quiet conditions are expected.
III. Event Probabilities 26 Apr to 28 Apr
Class M20%20%20%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       25 Apr 127
  Predicted   26 Apr-28 Apr  125/120/120
  90 Day Mean        25 Apr 112
V. Geomagnetic A Indices
  Observed Afr/Ap 24 Apr  030/043
  Estimated     Afr/Ap 25 Apr  018/022
  Predicted    Afr/Ap 26 Apr-28 Apr  017/025-011/015-004/006
VI. Geomagnetic Activity Probabilities 26 Apr to 28 Apr
A. Middle Latitudes
Minor storm20%10%01%
Major-severe storm10%05%01%
B. High Latitudes
Minor storm30%15%01%
Major-severe storm15%10%01%

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