Viewing archive of Wednesday, 20 April 2011

Solar activity report

Report of Solar-Geophysical Activity 2011 Apr 20 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 110 Issued at 2200Z on 20 Apr 2011

IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z

Solar activity has been at low levels for the past 24 hours. Regions 1195 (S17E55) and 1193 (N16W20) remain areas of interest producing several B/C class events. The largest event was a C4/Sf at 20/1939Z from Region 1195. Behind Region 1195, just rotating onto the east limb, New Region 1196 (S27E69) is already producing C-class events. Note: The Penticton 10.7 cm radio flux appears to be flare enhanced.
IB. Solar Activity Forecast
Solar activity is expected to be at low levels with a slight chance for M-class events for the next three days (21-23 April).
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field has been unsettled to active with isolated minor storm periods observed at high latitudes. The increase in activity was due to the arrival of a coronal hole high-speed stream (CH HSS). Observations at the ACE spacecraft, over the past 24 hours, have shown the solar wind speed increase from 350-550 km/s and back down 500 km/s.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at quiet to unsettled levels for the next 2 days (21-22 April) as the effects of the CH HSS subside. Late on 21 April, a slow moving CME is expected to become geoeffective with quiet to unsettled conditions lasting for 24 hours. On day three (23 April), quiet conditions are expected to prevail.
III. Event Probabilities 21 Apr to 23 Apr
Class M15%15%15%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       20 Apr 117
  Predicted   21 Apr-23 Apr  115/115/115
  90 Day Mean        20 Apr 104
V. Geomagnetic A Indices
  Observed Afr/Ap 19 Apr  004/006
  Estimated     Afr/Ap 20 Apr  010/010
  Predicted    Afr/Ap 21 Apr-23 Apr  010/010-008/008-005/005
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
A. Middle Latitudes
Minor storm05%05%01%
Major-severe storm01%01%01%
B. High Latitudes
Minor storm10%10%01%
Major-severe storm01%01%01%

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