:Product: Weekly Highlights and Forecasts
:Issued: 2013 Oct 28 0344 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
21 - 27 October 2013
Solar activity was reached high levels. The period began at low
levels with several C-class events from Regions 1875 (N07, L=030
class/area Fkc/790 on 27 Oct) and 1877 (S12, L=009 class/area
Dkc/440 on 24 Oct) observed on 21 Oct. By 22 Oct moderate levels
were reached when Region 1875 produced three M-class events, the
largest an M4/1b at 22/2120 UTC associated with a 220 sfu Tenflare
and a Type II radio sweep (1955 km/s). Moderate levels continued on
23 Oct with three additional M-class flares from Region 1875 and
reached high levels early on 24 Oct when Region 1877 produced an
M9/1n at 24/0030 UTC. A faint, full-halo CME was observed with the
M9 event, along with Types II (1321 km/s) and IV radio emissions.
Model runs indicated potential impacts at Earth on 28 Oct. Region
1875 produced two additional M-class events on 24 Oct as well. High
levels continued through 25 Oct with five M flares and two X-class
events from Region 1882 (S08, L=292 class/area Dkc/390 on 27 Oct)
which had just rotated onto the east limb. The first X-class event
was an X1 at 25/0801 UTC accompanied by Types II (1240 km/s) and IV
radio emissions, along with a Costelli U radio signature including a
610 sfu Tenflare. The second was an X2 at 25/1503 UTC associated
with Types II (2078 km/s) and IV radio emissions with another
Costelli U signature including a 370 sfu Tenflare. The WSA-Enlil
model indicates the arrival of both of the CMEs associated with the
X flares on 28 Oct, around the same time as the CME associated with
the M9 flare. Region 1882 produced 4 additional M-class events on 26
Oct. These along with an M3/Sf at 26/1927 UTC from Region 1884 (S13,
L=258 class/area Dso/110 on 27 Oct) kept solar activity at high
levels meeting the criteria by reaching five flares greater than or
equal to the M1 threshold. One of the flares from Region 1882 was an
M1/1n observed at 26/1117 UTC. CMEs were associated with this event
and the M3 from Region 1884. Model predictions indicated impacts
from the arrival of both CMEs on 29 Oct. Moderate activity levels
returned on 27 Oct with only a single M-class event, an M3/1f at
27/1248 UTC from Region 1875. Several other Type II and IV radio
sweeps along with multiple CMEs were observed during the period,
however none of them were determined to be geoeffective.
No proton events were observed at geosynchronous orbit, although
slight enhancements were observed following the M9 flare and the two
X flares observed on 24 and 25 Oct respectively.
The greater than 2 MeV electron flux at geosynchronous orbit began
the period at high levels on 21 Oct but quickly decreased to normal
to moderate levels for the remainder of the period.
Geomagnetic field activity was quiet throughout the period. A Sudden
Impulse (10 nT measured at the Boulder magnetometer) was observed at
26/2246 UTC. Based on timing, this most likely marked the arrival of
the CME associated theM4 flare observed late on 24 Oct.
Forecast of Solar and Geomagnetic Activity
28 October - 23 November 2013
Solar activity is likely to be at moderate levels through 06 Nov
when Region 1882 is expected to rotate around the west limb.
Predominately low levels are expected until Regions 1875 and 1877
return around 11 Nov. Chances for moderate activity increase at that
time and will persist until 20 Nov when activity is expected to
decrease again to low levels for the remainder of the period.
A chance for a proton event at geosynchronous orbit exists through
06 Nov as Regions 1875, 1877 and 1882 move across the western
hemisphere.
The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at normal to moderate levels through 10 Nov. An
increase to moderate to high levels is expected from 11 - 18 Nov
following a recurrent coronal hole high speed stream (CH HSS).
Normal to moderate levels are expected for the remainder of the
period.
Geomagnetic field activity is expected to be unsettled to active
with isolated minor storm intervals on 28 Oct due to a combination
of the 24 Oct CME associated with the M9 flare and the CMEs
associated with the two X flares observed on 25 Oct. Unsettled to
active conditions are expected on 29 Oct with a chance for minor
storm periods due to continued CME effects along with the arrival of
the CMEs from the 26 Oct M flares. Mostly quiet to unsettled levels
are anticipated from 30 - 31 Oct as CME effects wane and only a weak
CH HSS. Predominately quiet conditions are expected from 01 - 09
Nov. Quiet to unsettled conditions, with possible isolated active
periods, are expected from 10 - 13 Nov with the arrival of a
recurrent positive polarity CH HSS. Predominately quiet conditions
are expected for the remainder of the period.