:Product: Weekly Highlights and Forecasts
:Issued: 2018 Sep 24 0321 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
17 - 23 September 2018

Solar activity was at very low levels this period. There were no
numbered spot regions and no Earth-directed CMEs observed in
available satellite imagery. 

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reach
high levels on 17 - 23 Sep, with a peak flux of 34,900 pfu observed
at 17/0005 UTC.<o:p></o:p> 

Geomagnetic field activity was at quiet to unsettled levels from 17
- 19 Sep due to effects from a negative polarity coronal hole high
speed stream (CH HSS). Wind speeds began the period on 17 Sep near
370 km/s, but increased to over 500 km/s following the onset of the
CH HSS, seeing a peak speed near 587 km/s. Total field strength
reached 12 nT while the Bz component saw isolated southward
deflections to near -7 nT. Conditions returned to quiet levels on 20
Sep and most of 21 Sep, until the last synoptic period, when a SSBC
ahead of a positive polarity CH HSS, increased activity to G1 Minor
storm levels. The enhanced conditions continued into 22 Sep, with G1
storm levels reached the first period, and unsettled to active
conditions continuing throughout the day. Wind speeds took a while
to increase, but along with the SSBC from negative to positive, a
CIR enhanced the mag field, increasing total field strength to
approximately 11 nT and dropped the Bz component to near -11 nT.
Wind speeds eventually increased to reach a peak of 574 km/s late on
22 Sep. By 23 Sep, conditions remained slightly enhanced, with
active levels occurring the first synoptic period of the day, but
were beginning to subside. Quiet to unsettled conditions returned
for the remainder of the day as CH HSS influence continued to wane.
<o:p></o:p> 

Forecast of Solar and Geomagnetic Activity
24 September - 20 October 2018

Solar activity is expected to be at very low levels throughout the
outlook period, with a slight chance for C-class flare activity. 

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at moderate to high levels through the period.
Moderate levels are expected from 06 - 08 Oct. High levels are
expected from 24 Sep - 05 Oct, and 09 - 20 Oct. 

Geomagnetic field activity is expected to be at G1 (Minor)
geomagnetic storm levels on 7, 8, 10, and 19 Oct due to recurrent
positive polarity coronal hole high speed streams (CH HSSs). There
is a chance for G2 storm levels on 8 Oct as well. Active levels are
expected on 24 Sep, and 2, 10, and 20 Oct from the influence of the
recurrent CH HSSs as well. Field activity is expected to be at quiet
to unsettled levels throughout the remainder of the outlook period.