Viewing archive of Wednesday, 20 April 2005

Solar activity report

Report of Solar-Geophysical Activity 2005 Apr 20 2210 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA, #Space Environment Center and the U.S. Air Force. #

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 110 Issued at 2200Z on 20 Apr 2005

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

Solar activity was very low. Region 755 (S12E37) produced a B 8 flare at 19/2217 UTC with an associated Type II radio sweep (estimated speed of 1128 km/s) and a CME with an estimated speed of 776 km/s. The CME was directed to the east and is not expected to be geoeffective. No new regions were numbered today.
IB. Solar Activity Forecast
Solar activity is expected to be very low with a slight chance for an isolated C-flare.
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic field was at quiet to minor storm levels. Heightened activity was due to a solar sector boundary followed by the onset of a coronal hole high speed stream. Solar wind speed at ACE increased from approximately 350 km/s to 600 km/s. By the end of the period, solar wind speed had decreased to approximately 450 km/s.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be quiet to unsettled with isolated active conditions possible on 21 April. On 22 April, conditions are expected to increase to unsettled to active with minor storm periods possible as another coronal hole high speed stream is expected to become geoeffective. On 23 April, unsettled to active conditions are expected.
III. Event Probabilities 21 Apr to 23 Apr
Class M01%01%01%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       20 Apr 077
  Predicted   21 Apr-23 Apr  080/080/080
  90 Day Mean        20 Apr 091
V. Geomagnetic A Indices
  Observed Afr/Ap 19 Apr  006/008
  Estimated     Afr/Ap 20 Apr  015/020
  Predicted    Afr/Ap 21 Apr-23 Apr  010/015-015/018-012/015
VI. Geomagnetic Activity Probabilities 21 Apr to 23 Apr
A. Middle Latitudes
Minor storm10%15%10%
Major-severe storm01%05%05%
B. High Latitudes
Minor storm15%15%15%
Major-severe storm05%05%05%

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