:Product: Weekly Highlights and Forecasts
:Issued: 2011 Nov 01 2020 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
24 - 30 October 2011

Solar activity has been at very low to low levels. Very low levels
were observed on 24 October while low levels dominated the remainder
of the summary period. Despite the large size and magnetic
complexity (Beta-Gamma) of Region 1330 (N08, L=249, class/area,
Eko/560 on 24 October), the region only managed three low level
C-flares on 25 and 30 October. Region 1324 (N11, L=305, class/area,
Ekc/360 on 20 October) was the largest producer of low level C-class
activity with a total of five flares; the largest of the period, a
C3 that occurred at 29/1452 UTC. Four relatively slow-moving CMEs
were observed in association with disappearing solar filaments
beginning at 22/0058 UTC, 26/0800 UTC, and 28/0218 UTC, and finally
28/1652 UTC, observed in SOHO/LASCO imagery. The first event became
geoeffective late on 24 October while a glancing blow from the
second event arrived early on the 30 October, and third CME is not
expected to be geoeffective. The final CME is expected to arrive
sometime on 31 October.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal levels the entire period.

The geomagnetic field ranged from quiet to severe storm levels. The
period began with solar wind speeds, as measured by the ACE
Spacecraft, steady near 300 km/s with the total interplanetary
magnetic field (IMF Bt) around 6 nT. The geomagnetic field was quiet
during these periods. By late on 24 October, an interplanetary shock
was observed in ACE data at 24/1748 UTC in association with the CME
from 22/0058 UTC. A Sudden Impulse (SI) was observed at the Boulder
magnetometer of 13 nT at 24/1832 UTC. Solar wind velocities
increased from a steady 350 km/s to about 525 km/s. The IMF Bt
increased to above 20 nT from about 24/2000 UTC through 25/1300 UTC
and gradually decreased to about 8 nT by late on 25 October. The Bz
component of the IMF reached southward values of -20 nT from about
24/2000 UTC through 25/0000 UTC. The geomagnetic field from 24/1800
UTC - 25/1200 UTC responded with active to major storm periods with
an isolated severe storm period observed from 24/2100-2400 UTC. By
26 October, solar wind speed declined to around 400 km/s with the
IMF Bt around 7 nT. Solar wind speed continued to decline to
approximately 300 km/s by the end of the period. The geomagnetic
field was mostly quiet the rest of the period.

Forecast of Solar and Geomagnetic Activity
02 November - 28 November 2011

Solar activity is expected to be at predominately low to moderate
levels from 02 November - 15 November as Regions 1338 (S12, L=119,
class/area Dao/120 on 01 November) and 1339 (N22, L=117, class/area
Dao/180 on 01 November) rotate further onto the visible solar disk.
A return to mostly low levels is expected for the remainder of the
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 throughout the period.

The geomagnetic field is expected to be generally unsettled on 02
November as the effects of a CME wane. Predominantly quiet
conditions are expected from 03-04 November. An increase to
unsettled to active conditions is expected from 05-07 November as
the combined effects of a coronal hole high speed stream (CH HSS)
and another CME are expected. A return to quiet levels is expected
from 08-10 November. Another small increase to unsettled conditions
is expected from 11-13 November, as another CH HSS becomes
geoeffective. A return to predominantly quiet levels is expected
from 14 - 25 November. Quiet to unsettled levels are expected for
the remainder of the period, as another CH HSS becomes geoeffective.