This just in from the Australian Space
Forecast Centre at 2349 UTC on April 20, 2017:
Recurrent coronal hole is expected to be
geoeffective.
INCREASED GEOMAGNETIC ACTIVITY
EXPECTED
DUE TO CORONAL HOLE HIGH SPEED WIND
STREAM
FOR 23 APRIL 2017
GEOMAGNETIC ACTIVITY FORECAST
23 Apr: Active to Minor Storm
Spaceweather.com reported old sunspot AR2644
returned after a 2-week trip around the Sun, and exploded on April 18. The
resulting CME should miss Earth, but as this active region moves into a
geo-effective position we could see some geomagnetic disturbance in the next few
days.
Average daily sunspot numbers declined
from 16.6 last week to 8.6 in this reporting week, April 13-19. Average daily
solar flux increased from 73.8 to 76.5.
Geomagnetic indicators were lower this
week. Average planetary A index declined from 10.6 to 8, while average
mid-latitude A index was 6.3, down from 9.3 the previous seven days.
Predicted solar flux is 85 on April
21-27, 80 on April 28 to May 1, 75 on May 2-13, 83 and 88 on May 14-15, 90 on
May 16-18, 85 on May 19-24, 80 on May 25-28, and 75 on May 29 through June
4.
Predicted planetary A index is 12, 8, 40
and 30 on April 21-24, 20 on April 25-27, then 15, 10, 5 and 20 on April 28
through May 1, 10 on May 2-4, 15 on May 5-6, then 5 and 8 on May 7-8, 5 on May
9-13, 20 on May 14, 15 on May 15-16, 10 on May 17, 5 on May 18-19, then 35, 25,
18, 20 and 25 on May 20-24, then 12, 8, 5 and 18 on May 25-28, and 10 on May 29
through June 4.
František K. Janda, OK1HH, of the Czech
Propagation Interest Group sent us his geomagnetic activity forecast for the
period April 21-May 17, 2017. 2017 marks the 40th year Franz has been writing
these bulletins.
Geomagnetic field will be:
Quiet on April 22, 30, May 13
Mostly quiet on April 29, May
8
Quiet to unsettled April 21, May 3, 7,
10-12, 14-15
Quiet to active on April 24-25, 27-28,
May 1-2, 4-5, 8, 16
Active to disturbed on April 23, 26, May
6, 17
Increasing solar wind from coronal holes
are expected on April (21-22,) 23-28, May (1-4,) 7-8, (9-11,) and
18-19.