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  Weekly Space Weather Highlights
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Highlights of Solar and Geomagnetic Activity
16 - 22 October 2017

Solar activity was at very low levels with the exception of 20 Oct
when an M1 flare was observed on the southeastern limb. The M1 flare
occurred at 20/2328 UTC from Region 2685 (S09, L=131, class/area
Hax/070 on 22 Oct) with an associated Type II (344 km/s) radio sweep
and a coronal mass ejection (CME) off the east limb first observed
at 21/0012 UTC in SOHO/LASCO C2 imagery. By the time Region 2685
rotated fully into view, it was a simple alpha spot group and has
been quiet since the M-class event. No Earth-directed CMEs were
observed during the period. 

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached
moderate levels on 20 and 22 Oct with high levels on 16, 19 and 21
Oct. Very high levels were observed on 17-18 Oct. The largest flux
of the period was 56,839 pfu observed at 17/1535 UTC. 

Geomagnetic field activity ranged from quiet to active levels. The
period began under the weakening influence of a polar connected,
positive polarity coronal hole high speed stream (CH HSS). Solar
wind speed declined from approximately 550 km/s early in the period
to near 350 km/s by late on 18 Oct. Total field was at 5 nT and
below during this timeframe. The geomagnetic field responded with
quiet to unsettled levels on 16 Oct and quiet levels on 17-18 Oct.
By 19 Oct, a weak connection with the positive polarity polar CH was
observed resulting in a brief increase of solar wind speed to near
470 km/s and total field at 10 nT. Solar wind speed again decreased
to nominal levels by early on 21 Oct. The geomagnetic field
responded with quiet to unsettled levels on 19 Oct and quiet to
active levels on 20 Oct. A solar sector boundary crossing into a
negative sector was observed at 21/0730 UTC followed by a weak
enhancement from a negative polarity CH HSS. Solar wind speed
increased to near 490 km/s late on 21 Oct with total field
increasing to near 10 nT. By late on 22 Oct, solar wind parameters
had once again decreased to nominal levels. The geomagnetic field
responded with quiet to unsettled levels on 21-22 Oct. 

Forecast of Solar and Geomagnetic Activity
23 October - 18 November 2017

Solar activity is expected to be at very low to low levels with a
slight chance for M-class flares (R1-Minor) on 23-06 Nov due to
potential flare activity from Region 2685 and the return of old
Region 2683 (N13, L=111) to the visible disk. From 07-18 Nov, only
very low levels are expected. 

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
likely to be at high levels on 25-26 Oct, 28 Oct-01 Nov, 08-10 Nov,
12 Nov, 15 Nov and 17 Nov with very high levels on 27 Oct, 11 Nov
and13-14 Nov due to CH HSS influence. 

Geomagnetic field activity is expected to be unsettled to active
levels on 24-29 Oct, 01-02 Nov, 07-11 Nov and 15-17 Nov with G1
(Minor) storm levels likely on 24-26 Oct, 07-11 Nov and G2
(Moderate) levels likely on 25-26 Oct and 09-10 Nov due to recurrent
CH HSS effects.