SB PROP @ ARL $ARLP002
ARLP002 Propagation de K7RA
ZCZC AP02
QST de W1AW
Propagation Forecast Bulletin 2 ARLP002
From Tad Cook, K7RA
Seattle, WA January 8, 2021
To all radio amateurs
SB PROP ARL ARLP002
ARLP002 Propagation de K7RA
Sunspots disappeared after January 2, so the average daily sunspot
number dropped from 27.1 last week to 10 for this reporting week,
December 31 through January 6.
As a result, average daily solar flux declined as well, from 86.4 to
78.6.
Geomagnetic indicators remain quiet, with planetary A index changing
from 6.9 to 5.1, and middle latitude numbers from 5 to 4.
This decline was unexpected, and of course we would rather see more
and more sunspots as Solar Cycle 25 progresses, but this is normal. We
expect much variability in any sunspot cycle.
Predicted solar flux for the next 30 days looks depressed, far
different from the high 80s we saw around Christmas. Solar flux is
expected at 74 on January 8-15, 80 on January 16, 82 on January
17-27, 80 on January 28-31, and 78 on February 1-6. Flux values may
rise to 82 around mid-February.
Planetary A index is predicted at 5 on January 8-9, 8 on January
10-11, 5 on January 12-16, 10 on January 17-20, 5 on January 21-24,
8 on January 25-26, 5 on January 27-31, then 10, 10 and 8 on
February 1-3, and 5 on February 4-5. A index may rise to 10 by
mid-February.
This prediction, prepared by the US Air Force, is updated daily,
usually after 2120 UTC, and can be found at,
ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ .
Geomagnetic activity forecast for the period January 8 to February
3, 2021 from OK1HH.
"Geomagnetic field will be,
quiet on: January 10, 12-14, 22, 30-31
quiet to unsettled on: January 11, 23, 27-29, February 1
quiet to active on: January 8, 15-16, 21, 24-26
unsettled to active: January 9, 17, 19-20, February 3
active to disturbed: January 18, February 2
Solar wind will intensify on: (January 8-9, 15-17, 19-20,) 21 (- 22,
(23, 25-26,) February 2-3.
"Parenthesis means lower probability of activity enhancement. The
predictability of changes is lower again, as there are ambiguous and
changing indications. Including rapidly emerging and disappearing
narrow bands of solar coronal holes."
If you would like to make a comment or have a tip for our readers,
please email the author at, k7ra@arrl.net .
For more information concerning radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals.
For an explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.
An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/.
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
Sunspot numbers for December 31, 2020 through January 6, 2021 were
25, 23, 22, 0, 0, 0, and 0, with a mean of 10. 10.7 cm flux was
81.2, 80.4, 81.5, 80.4, 77.6, 75.1, and 74.1, with a mean of 78.6.
Estimated planetary A indices were 3, 4, 2, 2, 3, 11, and 11, with a
mean of 5.1. Middle latitude A index was 2, 3, 1, 1, 3, 9, and 9,
with a mean of 4.
NNNN
/EX
