Viewing archive of Friday, 6 April 2001

Solar activity report

Report of Solar-Geophysical Activity 2001 Apr 06 2200 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 096 Issued at 2200Z on 06 Apr 2001

IA. Analysis of Solar Active Regions and Activity from 05-2100Z to 06-2100Z

Solar activity has been high during the past 24 hours. Region 9415 (S21E33) produced an X5/Sf flare at 1921Z (Please note that the optical class could only be measured well after the x-ray flare maximum due to weather hampering observations). Coronagraph observations from SOHO/LASCO showed a CME associated with this event just entering the C2 field of view at 1930Z. Region 9415 is the dominant region on the disk with 820 millionths area in an Eko, beta-gamma-delta configuration. The only other solar flares of note today were a few C-class subflares. Coronagraph data also showed that yesterday's CME, associated with the long-duration M5 event, could be classified as a full-halo event. Nonetheless the sequence of images give the impression that the center of the CME is not headed directly at the Earth. Note that today's 10.7 cm flux had to be estimated from the morning reading because intense solar radio burst activity interfered with the normal noontime reading.
IB. Solar Activity Forecast
Solar activity is expected to be moderate to high during the next three days. Region 9415 is clearly the dominant region on the disk to watch for energetic flare activity, although regions 9417 and 9418 might possibly contribute a low-level M-class event.
IIA. Geophysical Activity Summary 05-2100Z to 06-2100Z
The geomagnetic field was mostly quiet to unsettled during the past 24 hours. Solar wind speeds continue to decline and solar wind density remains low. The greater than 10 MeV proton event continued to decline during the past 24 hours. As of 06/2100Z the fluxes were fluctuating below and above the threshold of 10 PFU, with a reading of 10.2 PFU at 2100Z.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be unsettled for the next 24 hours. An increase to active levels is expected on the second and third days as a response to a glancing blow from the halo CME associated with yesterday's M5 flare and possible additional influence from the CME associated with today's X5 event. There is a fair chance for an increase in the greater than 10 MeV proton fluxes sometime in the next 24 hours in response to today's X5 event as well, although the fluxes are likely to increase rather gradually with peak fluxes in the low 100's of PFU, and the spectrum will probably be relatively soft.
III. Event Probabilities 07 Apr to 09 Apr
Class M80%80%80%
Class X25%25%25%
IV. Penticton 10.7 cm Flux
  Observed       06 Apr 192
  Predicted   07 Apr-09 Apr  200/195/190
  90 Day Mean        06 Apr 167
V. Geomagnetic A Indices
  Observed Afr/Ap 05 Apr  011/019
  Estimated     Afr/Ap 06 Apr  012/015
  Predicted    Afr/Ap 07 Apr-09 Apr  012/012-025/025-025/025
VI. Geomagnetic Activity Probabilities 07 Apr to 09 Apr
A. Middle Latitudes
Minor storm10%20%20%
Major-severe storm05%25%30%
B. High Latitudes
Minor storm15%25%25%
Major-severe storm05%15%30%

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