Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 25 Apr 2004

By SpaceRef Editor
April 25, 2004
Filed under , ,

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2004 Apr 25 2230 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 116 Issued at 2200Z on 25 Apr 2004

IA. Analysis of Solar Active Regions and Activity from 24/2100Z
to 25/2100Z: Solar activity was moderate. Region 599 (N16E28)
produced an M2/1N flare today at 0537 UTC, as well as a number of
smaller, C-class events. The group continued to grow today, and
shows some magnetic complexity, particularly just behind the large
leader spot where smaller spots of opposite polarity are in close
proximity. Most of the flare brightenings occurred along an
east-west inversion line in the mid-to-trailing portion of the
region. Region 596 (S08W36) is still the largest group on the disk,
but was quiet and appears to be slowly decaying.

IB. Solar Activity Forecast: Solar activity is expected to be
mostly low, but there is a fair chance for an additional, isolated
M-class event during the next three days from Region 599.

IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z:
The geomagnetic field was mostly unsettled. There was an isolated
active period at high latitudes from 0600-0900 UTC. Solar wind data
show continuation of a weak, high-speed stream, with velocities
ranging mostly between 500-550 km/s.

IIB. Geophysical Activity Forecast: The geomagnetic field should
persist at the current, mostly unsettled levels for the next 24-36
hours (26 April to partway through 27 April). A decrease is expected
to begin partway through the 2nd day (27 April) and quiet to
unsettled levels should prevail on the third day (28 April).

III. Event Probabilities 26 Apr-28 Apr

  • Class M 35/35/35
  • Class X 05/05/05
  • Proton 05/05/05
  • PCAF green

IV. Penticton 10.7 cm Flux

  • Observed 25 Apr 107
  • Predicted 26 Apr-28 Apr 110/110/110
  • 90 Day Mean 25 Apr 107

V. Geomagnetic A Indices

  • Observed Afr/Ap 24 Apr 007/011
  • Estimated Afr/Ap 25 Apr 010/010
  • Predicted Afr/Ap 26 Apr-28 Apr 012/012-010/010-005/008

VI. Geomagnetic Activity Probabilities 26 Apr-28 Apr

A. Middle Latitudes

  • Active 25/20/15
  • Minor storm 20/15/10
  • Major-severe storm 10/05/05

B. High Latitudes

  • Active 35/30/25
  • Minor storm 25/20/15
  • Major-severe storm 15/10/05

SpaceRef staff editor.