Propagation Forecast Bulletin #21 de K7RA:
W1AW Bulletin via the ARRL
May 24, 2013
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Propagation Forecast Bulletin #21 de K7RA:
QST de W1AW
Propagation Forecast Bulletin 21 ARLP021
>From Tad Cook, K7RA
Seattle, WA May 24, 2013
To all radio amateurs
SB PROP ARL ARLP021
ARLP021 Propagation de K7RA
Overall, solar activity is still pretty quiet, but one positive sign
was on May 16, when the daily sunspot number was 212. I eyeballed
the records, and had to keep searching further and further back to
find a higher sunspot number.
One year, six months and one week earlier, on November 9, 2011 the
sunspot number was nearly that high, at 208. We look clear back
seven years, 10 months and 12 days to July 4, 2005, another near
miss at 192. To find activity beating the May 16 number we have to
go back nearly a decade, to November 1, 2003 when the daily sunspot
number was 277. This was way back on the downward slide of cycle
23, nine years, six months and 15 days earlier than our recent high
number. Let's hope for many more days like this. That seems
likely, as the peak of this solar cycle is predicted for this fall,
which begins about four months from now, on Sunday, September 22.
Compared to the previous period (May 9-15) average daily sunspot
numbers this week were down over 12 points to 144. Average daily
solar flux sank nearly 6 points to 134.2. Geomagnetic activity was
higher, with average daily planetary A index up 3.7 points to 9.7,
and average daily mid-latitude A index up 4.4 points to 10.3. It
should be noted that five of the eight daily geomagnetic readings
which make up the A index were not recorded for May 16 at the mid-
latitude observatory, so the mid-latitude A index of 12 for that day
is an estimate.
The latest prediction from NOAA/USAF has solar flux at 135 on May
24-25, 130 on May 26-27, 135 on May 28-29, and then 130, 115, 105
and 110 on May 30 through June 2, 120 on June 3-5, and 125 on June
6-8, before rising to a short-term peak of 140 on June 12-13. This
prediction is a bit far off, but it also shows a minimum flux value
of 100 on June 26-27.
Turning to geomagnetic activity, predicted planetary A index is 15,
20, 12 and 8 on May 24-27, 5 on May 28 through June 10, and then 8,
12 and 8 on June 11-13, 5 on June 14-17, and then 15, 12, 8 and 5 on
June 18-21. On June 24, a month and about one solar rotation from
now, they show planetary A index rising from 5 to 15, perhaps an
echo of current geomagnetic activity.
OK1HH predicts active to disturbed geomagnetic conditions May 24,
quiet to active May 25, mostly quiet May 26-27, quiet to active May
28, quiet to unsettled May 29, quiet May 30, quiet to unsettled May
31 through June 1, mostly quiet June 2, quiet to unsettled June 3,
quiet June 4-8, mostly quiet June 9-10, quiet to active June 11,
active to disturbed June 12-13, quiet to unsettled June 14, and
mostly quiet June 15-16.
The CQ World Wide WPX Contest, CW weekend begins tonight/tomorrow at
0000 UTC May 25. The geomagnetic activity predicted for this
weekend may add some additional challenge to the test, which has a
new set of rules. The multiplier used is the number of unique call
sign prefixes of stations worked. See details at
The current geomagnetic activity is due to a May 22 M5 class solar
flare, which is expected to deliver a glancing blow to our
geomagnetic field today, May 24.
Jon Jones, N0JK reports that during a six meter e-layer opening last
Sunday evening observed from coast to coast in North America, a rare
Australia to North America opening took place. From 2355 UTC on May
19 until 0032 UTC on May 20 on CW VK4MA worked W9FF, NW0W, K9ZM,
WZ8D, W9WZJ and K0GU. It appears the longest distance was to WZ8D,
about 9,041 miles. N0JK believes the propagation path was via
e-layer linked to trans-equatorial propagation.
Last Friday, May 17 Jim Smith, K3RTU took his backpack rig into
Ridley Creek State Park in Southeast Pennsylvania (FM29). He wrote:
"After some hiking I set up my Buddistick vertical and new KX3 about
1730. I tried 15 meters first, but had no luck and only heard a few
stations, so I readjusted the antenna for 17 meters and after a few
minutes worked Duncan, EA5ON/M with SSB and got a 54 report. Not
too bad for vertical to vertical, but the QRN on his end was
troublesome. Duncan told me it was raining there with lots of
atmospheric noise and later contacts with Western Europe confirmed
the bad weather was pretty wide spread. Then over the next two
hours worked Dave VP5/W5CW (my report 59), Mario DJ2OR (55), Carolyn
W5/G6WRW near Santa Fe, NM (53), Al VE7WJ (53), Joe DF9ZP (59),
KB5AVE (56), and last, Mike IF9ZWA (55) on Favignana Island off the
coast of Sicily. What amazed me the most was that I had good
propagation both east and west of my location which I don't always
find to be the case."
And finally, I just ran across a previously overlooked email from
Wayne Mills, N7NG of Jackson Hole, Wyoming sent on January 4, 2013,
reflecting on cycle 19. Wayne said, "I have seen all of the solar
peaks since 1956. What I have to say, however, is that I had
absolutely no expectation of what cycle 20 might be like. The
reason was that when I was a sophomore in high school in 1958, I had
NO IDEA what sunspots were.
I started working DX in 1956 with 90 watts and a low 40M dipole. I
was on 20M CW ONLY. No worries about other bands, what might be
open, what long paths might be open. Just listen and work what I
It was just a few high school friends and me; we had very little
contact with local DXers. Eventually, I ran into W6MX (Honor Roll
1955) and W6BAX, a serious DXer and learned a few things.
Soon, I put up a 2 element 20M beam, and then I had to worry about
where to point it. Still, it took more than 2 years to work DXCC.
Things will never be the same."
For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://arrl.org/propagation-of-rf-signals. For an explanation of
the 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
Monthly propagation charts between four USA regions and twelve
overseas locations are at
Sunspot numbers for May 16 through 22 were 212, 198, 146, 113, 113,
119, and 107, with a mean of 144. 10.7 cm flux was 144.7, 136.4,
132.1, 135.3, 132, 125.3, and 133.4, with a mean of 134.2.
Estimated planetary A indices were 14, 9, 21, 12, 7, 7, and 12, with
a mean of 9.7. Estimated mid-latitude A indices were 12, 9, 16, 11,
6, 8, and 10, with a mean of 10.3.
Source: W1AW Bulletin via the ARRL.
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