Viewing archive of Sunday, 27 April 2003

Solar activity report

Report of Solar-Geophysical Activity 2003 Apr 27 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 27 Apr 2003

IA. Analysis of Solar Active Regions and Activity from 26-2100Z to 27-2100Z

Solar activity decreased to moderate levels. Region 338 (N18W85) produced an M2.5/Sf at 26/2340Z and an M1.7/Sf at 27/1532Z which were the largest flares of the period. This region was again responsible for the vast majority of the activity observed today. Proximity to the west limb hinders analysis of changes in magnetic structure today. Region 344 (N16W00) showed slight growth today and retains a beta-gamma-delta structure. The weak delta complex is evident in the northwestern quadrant of the dominant trailing spot. Region 337 (S14W40) underwent rapid growth during the period adding many additional spots to the south of the main body of this group. This region also depicts a beta-gamma-delta magnetic structure. A 34 degree solar filament erupted yesterday at approximately 26/2000Z which resulted in a streamer CME that does not appear as though it will become geoeffective No new regions were numbered today.
IB. Solar Activity Forecast
Solar activity is expected to be at moderate levels. Region 338 has begun to transit the disk but remains capable of producing a major flare.
IIA. Geophysical Activity Summary 26-2100Z to 27-2100Z
The geomagnetic field was at quiet to active levels. An increase of 150 km/s in the solar wind speed during the period is believed to be the result of a recurrent coronal hole. The greater than 2 MeV electron fluxes at geosynchronous orbit reached high levels again today.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be at predominantly unsettled to active levels through the interval. High latitude minor storm conditions are possible on day one and into day two due to a favorably positioned coronal hole.
III. Event Probabilities 28 Apr to 30 Apr
Class M70%50%50%
Class X15%10%05%
IV. Penticton 10.7 cm Flux
  Observed       27 Apr 154
  Predicted   28 Apr-30 Apr  155/160/155
  90 Day Mean        27 Apr 127
V. Geomagnetic A Indices
  Observed Afr/Ap 26 Apr  009/015
  Estimated     Afr/Ap 27 Apr  012/012
  Predicted    Afr/Ap 28 Apr-30 Apr  015/015-012/015-012/015
VI. Geomagnetic Activity Probabilities 28 Apr to 30 Apr
A. Middle Latitudes
Minor storm20%15%10%
Major-severe storm10%05%05%
B. High Latitudes
Minor storm30%25%15%
Major-severe storm15%10%05%

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