Viewing archive of Monday, 26 April 2004

Solar activity report

Report of Solar-Geophysical Activity 2004 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 2004

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

Solar activity was low. There was only one C-class event during the past 24 hours, a C2/Sf from Region 599 (N16E15) at 0242 UTC. Although this region emerged rapidly yesterday, the past 24 hours have see a noticeable decrease in spot area, flare production, and overall brightness of the region. New Region 600 (N18W06) emerged on the disk today as a small beta-type sunspot group.
IB. Solar Activity Forecast
Solar activity is expected to be predominantly low for the next three days. There is a slight chance for an isolated M-class event.
IIA. Geophysical Activity Summary 25-2100Z to 26-2100Z
The geomagnetic field was quiet to unsettled. Mostly quiet conditions prevailed early in the day as solar wind signatures showed a gradual declining trend in solar wind velocity with very weak interplanetary magnetic field, up until around 1520 UTC. Beginning around 1520 UTC a compression wave followed by some transient flow was observed: density, velocity, temperature and magnetic field all increased over a few minutes, and Bz showed a rotation over 2-3 hours from +5 to around -7 nT. The geomagnetic field responded by an increase to unsettled levels.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be predominantly unsettled for the next 24 hours (27 April). Quiet to unsettled levels are expected to prevail for the second and third days (28-29 April).
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 100
  Predicted   27 Apr-29 Apr  100/095/090
  90 Day Mean        26 Apr 107
V. Geomagnetic A Indices
  Observed Afr/Ap 25 Apr  007/012
  Estimated     Afr/Ap 26 Apr  007/007
  Predicted    Afr/Ap 27 Apr-29 Apr  010/010-005/008-005/008
VI. Geomagnetic Activity Probabilities 27 Apr to 29 Apr
A. Middle Latitudes
Minor storm15%10%10%
Major-severe storm10%05%05%
B. High Latitudes
Minor storm20%15%15%
Major-severe storm15%05%05%

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