:Product: Weekly Highlights and Forecasts
:Issued: 2011 Dec 13 1738 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# http://www.swpc.noaa.gov/weekly.html
#
# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
05 - 11 December 2011

Solar activity was at predominantly low levels for the summary
period. From 05 - 06 December, two regions dominated the disk in
size and solar flare production, Region 1363 (S21, L=108,
class/area=Eki/620 on 05 December) and Region 1362 (N08, L=131,
class/area=Eso/220 on 03 December). Both regions produced multiple
C-class events with Region 1363 responsible for the largest event of
the period, a C6/Sf flare at 05/2325 UTC. From 07 - 10 December,
Region 1374 (S17, L=352, class/area=Dso/210 on 11 December) and
Region 1375 (N08, L=356, class/area=Cso/140 on 11 December)
dominated the disk, each producing several small C-class events. The
only days of the summary period with activity at very low levels
were 06 and 11 December . Multiple coronal mass ejections (CMEs)
were observed throughout the week, however, none of them were
geoeffective.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
moderate levels from 05 - 09 December. A return to background levels
was observed on 10 December.

Geomagnetic activity was at predominantly quiet levels during the
summary period. From 05 - 08 December, quiet conditions were
observed at all latitudes. On 09 December, an isolated period of
active conditions was observed at high latitudes. On 10 December,
quiet to unsettled conditions were observed as a coronal hole high
speed stream (CH HSS) moved into a geoeffective position. Solar wind
speed increased from around 330 km/s to around 500 km/s at the ACE
spacecraft and the total IMF rose to around 11 nT. Another isolated
period of active conditions was observed at high latitudes on 11
December as a result of the CH HSS effects.

Forecast of Solar and Geomagnetic Activity
14 December - 09 January 2012

Solar activity is expected to be at predominately low levels with a
chance for isolated M-class activity from 12 - 22 December. A
decrease to predominantly low levels is expected from 23 -24
December as Regions 1374 and 1375 rotate off the disk. An increase
to a slight chance for M-class activity is expected on 25 December
as Region 1363 returns and remain for the duration of the forecast
period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels the entire forecast
period (14 December - 09 January).

Geomagnetic field activity is expected to be at mostly quiet levels
from 14 - 25 December. Quiet to unsettled conditions are expected on
26 - 29 December due to effects from a recurrent CH HSS. A return to
quiet levels is expected from 30 December - 04 January followed by
an increase to quiet to unsettled levels on 05 - 06 January due to
effects from a second recurrent CH HSS. Mostly quiet conditions are
expected for the remainder of the period.