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  Weekly Space Weather Highlights
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Highlights of Solar and Geomagnetic Activity
18 - 24 October 2021

Solar activity was very low. Background x-ray enhancement began on
20 Oct as new Regions 2886 (S19, L= 338, class/area Hsx/185 on 19
Oct) and 2887 (S25, L=278, class/area Dki/440 on 24 Oct) emerged
around the SE limb on 17 Oct and 21 Oct, respectively. Region 2886
was quiet and stable while Region 2887 produced the majority of the
B-class flare activity. The largest flare of the period was a B9.6
flare at 22/1838 UTC from a region just beyond the East limb. No
Earth-directed CMEs were observed. 

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at
normal to moderate levels with a peak flux of 433 pfu at 18/1700
UTC. 

Geomagnetic field activity ranged from quiet to active levels. The
period began under the influence of a weak transient with total
field reaching 13 nT and the Bz component reaching -8 nT late on 17
Oct. Solar wind speed ranged from 325-385 km/s during this time.
Slightly perturbed conditions continued on 19-20 Oct as a solar
sector boundary crossing followed by a co-rotating interaction
region preceded the onset of a negative polarity coronal hole high
speed stream (CH HSS). Solar wind speed increased to 555 km/s early
on 21 Oct. Nominal solar wind conditions returned by midday on 23
Oct. The geomagnetic field responded with quiet to active levels on
18-19 Oct, quiet to unsettled conditions on 20 Oct, and quiet levels
thereafter. 

Forecast of Solar and Geomagnetic Activity
25 October - 20 November 2021

Solar activity is expected to be at very low to low levels with a
slight chance for M-class (R1-R2, Minor-Moderate) flares on 25 Oct -
03 Nov as Region 2887 transits across the visible disk. Very low
levels are expected from 04 Nov -15 Nov. Very low to low levels are
expected again on 16-20 Nov with the return of Region 2887. 

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 forecast
period. 

Geomagnetic field activity is expected to reach unsettled levels on
27-30 Oct, 06-08 Nov, and 15-16 Nov and active levels on 06 Nov due
to CH HSS activity.