SB PROP @ ARL $ARLP031
ARLP031 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 31 ARLP031
From Tad Cook, K7RA
Seattle, WA July 30, 2021
To all radio amateurs
SB PROP ARL ARLP031
ARLP031 Propagation de K7RA
Solar activity slowed this week. Average daily sunspot number
declined to 33.9 this week (July 22 to 28) from 48.9 in last week's
report. Wednesday July 28 had no sunspots at all.
Average daily solar flux went from 81.3 to 83.
Geomagnetic indicators held steady, with average daily planetary A
index at 6.4 both last week and this week. Average daily middle
latitude A index went from 6.4 last week to 6.3 this week.
Predicted solar flux is 76 on July 30 and 31, then 74 on August 1,
72 on August 2 to 4, 74 on August 5 and 6, 75 on August 7 to 12,
then 78, 80, 82 and 85 on August 13 to 16, 90 on August 17 and 18,
85 on August 19 and 20, 80 on August 21, 82 on August 22 to 28, 78
on August 29, and 75 on August 30 to September 8.
Predicted planetary A index is 8, 12 and 8 on July 30 through August
1, 5 on August 2 to 9, 12 and 10 on August 10 and 11, 5 on August 12
to 15, 10 and 8 on August 16 and 17, 5 on August 18 to 23, then 12,
12 and 8 on August 24 to 26, 5 on August 27 and 28, 8 on August 29,
and 5 on August 30 through September 5.
F. K. Janda, OK1HH is on vacation this week hiking in the mountains
of the Czech Republic, so we have forecasts from two of his
"Solar activity forecast for the period July 30 to August 05, 2021
Activity level is mostly very low
X-ray background flux (1.0 to 8.0 A) in the range A5.5 to B1.5
Radio flux (10.7 cm) a fluctuation in the range 74 to 82
Events: class C (0 to 4/period), class M (0/period), class X
(0/period), proton (0/period)
Relative sunspot number (Ri) in the range 0 to 55"
"Geomagnetic activity forecast for the period July 30 to August 05,
Quiet on Jul 30 and 31, Aug 2 to 4
Unsettled on Jul 31, Aug 1 to 3, 5
No Active days
No Minor storms
No Major storms
No Severe storms
Geomagnetic activity summary:
Next week, we expect at most quiet to unsettled conditions. The
more unsettled events are possible about August 1 and 2, and also
about Thursday, August 5.
The other days, we expect quiet to unsettled conditions generally,
closer to quiet level."
"There was a big 2m Es opening from DN70 to the Midwest this
afternoon, July 24. I was busy with some chores then happened to
look at DXMaps and the APRS VHF propagation map and noticed a large
Es cloud located over eastern NE/western IA and another located over
SE KS. I quickly tuned into 2m FT8 144.174. Signals were very
strong, with +21 db the best report I sent and +29 the best
report I received. My QSOs, beginning at 2216z and ending at 2235
UTC were as follows:
Then followed 26 minutes of a mixture of single decodes, total
quiet, meteor bursts, but no QSOs. Then at 2301 UTC:
And then it was over. I don't know when the opening began since it
was well and truly in progress when I got to the radio, but it was
an amazing 20 minutes or so.
Unfortunately I was unable to complete with W3IP in FM19, which
would have been the longest distance QSO of the opening for me. We
heard each other over several sequences but were unable to finish
My station: Kenwood TS-2000, Beko HLV-1000 running at 750W, 10
element LFA (by G0KSC) at 35 feet.
73 - Jan, KC0V"
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service at http://arrl.org/propagation-of-rf-signals. For an
explanation of numbers used in this bulletin, see
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 July 22 through 28, 2021 were 77, 46, 35, 24,
25, 25, and 0, with a mean of 33.1. 10.7 cm flux was 89, 87.4 83.9,
81.6, 80.8, 79.6, and 78.8, with a mean of 83. Estimated planetary
A indices were 11, 4, 4, 3, 4, 6, and 13, with a mean of 6.4.
Middle latitude A index was 9, 3, 5, 5, 3, 6, and 13, with a mean of