Viewing archive of Friday, 27 May 2011

Solar activity report

Report of Solar-Geophysical Activity 2011 May 28 0225 UTC
Prepared by the NOAA © SWPC and processed by

Joint USAF/NOAA Report of Solar and Geophysical Activity

:::::::::: CORRECTED COPY :::::::::: SDF Number 147 Issued at 2200Z on 27 May 2011

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

Solar activity was low. New Region 1226 (S18E74) produced a B-class event and four C-class events since being numbered today. The largest was a C5 observed at 27/1643Z. This region began with a B1 event at 26/1654Z as it approached the southeast limb yesterday. It is currently an H-type group, however, the region is still rotating onto the disk and more white light area are evident in the SDO/HMI imagery just visible on the limb. Region 1223 (S16W00) produced the only other event during the period, a B4 at 27/0953Z. This region is a Dso group with a beta magnetic classification and grew slightly in sunspot count. Two more regions were numbered today as Regions 1224 (N21W15) and 1225 (N18E55). Region 1224 is a Dso group with a beta magnetic classification and 1225 is another H-type group.
IB. Solar Activity Forecast
Solar activity is expected to be low with a chance for C-class events, and a slight chance for an M-class event, as regions on the disk continue to evolve.
IIA. Geophysical Activity Summary 26-2100Z to 27-2100Z
The geomagnetic field was quiet to unsettled. Observations from the ACE spacecraft suggest the earth is under the continued influence of the co-rotating interaction region in advance of the recurrent coronal hole high speed stream. Solar winds have slowly increased from around 390 to 500 km/s. The IMF Bt averaged around 8 nT with the Bz mostly southward (-8 nT) through the period.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected to be predominately unsettled with occasional active periods, including isolated minor storm conditions at high-latitudes for day one (28 May). This is expected due to effects from the recurrent coronal hole high speed stream (CH HSS). In addition there are possible effects from the disappearing filament observed on 25 May. Quiet to unsettled conditions, with isolated active levels, are expected for days two and three (29-30 May) with continued CH HSS effects.
III. Event Probabilities 28 May to 30 May
Class M10%10%10%
Class X01%01%01%
IV. Penticton 10.7 cm Flux
  Observed       27 May 090
  Predicted   28 May-30 May  090/095/095
  90 Day Mean        27 May 108
V. Geomagnetic A Indices
  Observed Afr/Ap 26 May  004/007
  Estimated     Afr/Ap 27 May  010/012
  Predicted    Afr/Ap 28 May-30 May  015/018-010/012-008/008
VI. Geomagnetic Activity Probabilities 28 May to 30 May
A. Middle Latitudes
Minor storm10%05%05%
Major-severe storm05%01%01%
B. High Latitudes
Minor storm15%10%10%
Major-severe storm05%05%05%

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