:Product: Weekly Highlights and Forecasts
:Issued: 2004 Oct 26 2212 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Environment Center
# Product description and SEC contact on the Web
# http://www.sec.noaa.gov/weekly.html
#
#                Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
18 - 24 October 2004

Solar activity ranged from very low to moderate this period.  Very
low conditions were observed on 18 October.  Low levels occurred on
19, 21, and 23 October, while moderate levels were reached on 20, 22
and 24 October.  Two regions accounted for the majority of the
twenty four C-class and three M-class flares this summary period. 
Region 682 (S14, L=271, class/area, Dai/240 on 15 October) produced
ten low-level C-flares before rotating around the west limb on 24
October.  New Region 687 (N12, L=175, class/area, Eki/280 on 24
October) produced the majority of the period’s activity with twelve
C-class and three M-class flares.  The most significant event of the
period occurred on 22 October when Region 687 produced an M2.1/1n
flare at 0811 UTC.  Associated with this event were Type II (521
km/s shock velocity) and Type IV radio sweeps, and a CME on LASCO
imagery.

Solar wind data were available from the NASA Advanced Composition
Explorer (ACE) spacecraft during most of the summary period.  Solar
wind speed ranged from a low of near 300 km/s early on 18 October to
a high near 525 km/s late on the 24 October.  The period began on 18
October with very stable solar wind conditions.  Midday on 18
October, a solar sector boundary crossing was followed by elevated
solar wind plasma and the IMF Bz oscillating between +/- 10 nT.
These weak disturbed conditions persisted through 21 October.  Solar
wind gradually returned to more stable conditions.  By 24 October, a
weak geoeffective coronal hole wind stream was detected at ACE. 
Solar wind speed increased to over 500 km/s and the IMF Bz began
oscillating +/- 8 nT.

There were no greater than 10 MeV proton events at geo-synchronous
orbit during the summary period

The greater than 2 MeV electron flux at geosynchronous orbit was at
high levels on 18 and 19 October.

The geomagnetic field was at mostly quiet to unsettled levels.  A
brief period of active conditions were observed at mid latitudes
late on 24 October due to a weak, geoeffective coronal hole wind
stream.  Periods of southward Bz produced isolated major storm
periods at high latitudes on 20 October.

Forecast of Solar and Geomagnetic Activity
27 October - 22 November 2004

Solar activity is expected to be low to moderate through early
November and again from mid- November through the end of the
forecast period due to possible M-class flare activity from Region
687.  Otherwise, activity levels are expected to remain very low to
low.

A greater than 10 MeV proton event is possible through early
November.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at high levels on 10 – 13 November.

The geomagnetic field is expected to range from mostly quiet to
unsettled with isolated active periods.  From 09 – 11 November, a
recurrent coronal hole wind stream is expected to produce occasional
active to minor storm periods with isolated major storm periods at
high latitudes.