:Product: Weekly Highlights and Forecasts
:Issued: 2003 Dec 23 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
15 - 21 December 2003

Solar activity was at very low to low levels this period.  The period
began on 15 December with very low level activity.  From 16 – 21
December, activity was primarily at low levels.  Region 525 (N09,
L=291, class/area Dsi/130 on 21 December) underwent slow growth in
both size and complexity during the period, and developed a
beta-gamma magnetic configuration on 21 December.   This region
represents the third rotation of old Region 488 (previous rotation
was Region 507).  The majority of activity during the period came
from Region 525, including two C8/Sf flares on 17 and 18 December,
and the largest flare of the period, a C9/Sf at 0809 UTC on 19
December.  Region 528 (N09, L=259, class/area Fho/390 on 21
December) rotated onto the visible disk on 18 December, and
exhibited steady growth through most of the period.  On 21 December,
Region 528 was a moderate size beta-gamma spot group, producing
occasional C-class activity.

Solar wind data were available from the NASA Advanced Composition
Explorer (ACE) spacecraft during most of the summary period.  Solar
wind speeds were near 800 km/s at the beginning of the period due to
a large transequatorial coronal hole.  On 16 December, as the
coronal hole rotated beyond a geoeffective position, wind speed
began a steady decline to near 325 km/s by 19 December.  Another,
smaller elongated coronal hole rotated into a geoeffective position
on 20 – 21 December with wind speeds reaching 625 km/s; however, Bz
remained predominantly northward.

There were no greater than 10 MeV proton events at geosynchronous
orbit during the summary period.

The greater than 2 MeV electron flux at geosynchronous orbit reached
high levels on 15 – 20 December.

The geomagnetic field ranged from unsettled to minor storm levels.
The period began with activity at active to minor storm levels on 15
December.  As the coronal hole high speed stream diminished,
geomagnetic activity dropped to quiet to unsettled levels on 16 – 19
December.  The onset of the second elongated coronal hole high speed
stream produced unsettled to active conditions on 20 – 21 December.

Forecast of Solar and Geomagnetic Activity
24 December 2003 - 19 January 2004

Solar activity is expected to range from very low to moderate levels.
Moderate level activity is possible from Regions 525 and 528
through 31 December.  Expect mostly low activity levels in early
January.

There is a small chance for a greater than 10 MeV proton event until
the end of December.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to reach high levels on 03 – 04 January and again on 07 –
14 January.

Geomagnetic activity is expected to range from quiet to major storm
levels.  Unsettled to minor storm periods are expected on 01 – 02
January due to high speed coronal hole streams.  The large
transequatorial coronal hole is expected to return on 04 – 12
January with major storm levels expected.