Viewing archive of Tuesday, 17 April 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Apr 17 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 107 Issued at 2200Z on 17 Apr 2001

IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z

Solar activity has been low. There were several optically uncorrelated C-class events during the period. New Region 9431 (S10E49) was numbered today.
IB. Solar Activity Forecast
Solar activity is expected to be low with an isolated chance for a M-class event.
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic field was quiet to unsettled. The greater than 10 MeV proton event that started on April 15 is still in progress. The greater than 100 proton event that began at 15/1405 UTC reached a maximum of 146 pfu at 15/1525 UTC and ended at 17/0515 UTC. The polar cap absorption (PCA) event ended at 17/0315 UTC. The greater than 2 MeV electrons at geosynchronous orbit remained at high levels and above threshold through the period.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be unsettled to active for April 18 and 19 as a result of possible effects from the X14/2b event on April 15, and possible effects from a well positioned coronal hole. Quiet to unsettled conditions are expected to return on April 20. The greater than 10 MeV proton event is expected to go below threshold on April 18.
III. Event Probabilities 18 Apr to 20 Apr
Class M60%50%50%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       17 Apr 126
  Predicted   18 Apr-20 Apr  135/145/155
  90 Day Mean        17 Apr 165
V. Geomagnetic A Indices
  Observed Afr/Ap 16 Apr  007/007
  Estimated     Afr/Ap 17 Apr  008/015
  Predicted    Afr/Ap 18 Apr-20 Apr  020/025-015/020-010/015
VI. Geomagnetic Activity Probabilities 18 Apr to 20 Apr
A. Middle Latitudes
Minor storm10%05%05%
Major-severe storm05%01%01%
B. High Latitudes
Minor storm15%10%10%
Major-severe storm10%05%05%

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