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ARRL Propagation Bulletin ARLP021 (2011)

ARLP021 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 21  ARLP021
From Tad Cook, K7RA
Seattle, WA  May 27, 2011
To all radio amateurs 

ARLP021 Propagation de K7RA

The bulletin this week is coming to you from Felton, California,
where your author is attending a camp for blues dancers.
Our Sun was certainly quieter this week.  Average daily sunspot
numbers were down nearly 17 points to 51.6, and average daily solar
flux declined nearly 9 points to 83.2.  The latest prediction is for
solar flux to remain low at about 85 on May 27-29, 80 on May 30
through June 3, then rise to 90 on June 4, then 85 on June 5-7, and
back to 90 on June 8-11, peaking at 95 on June 12.
The same prediction has some geomagnetic activity this weekend, with
planetary A index on May 27-30 at 10, 15, 12, and 10, then declining
to 5 on May 31 and into the first week of June.  The moderate
activity on Saturday (May 28) is due to a solar wind stream.
Geophysical Institute Prague predicts unsettled conditions on May
27, active conditions May 28, unsettled May 29-31, and quiet on June
Things may seem quiet on this (the Earth-facing) side of our Sun,
but a peek at shows much more activity
on the far side.  All those white spots represent magnetic activity,
and some could indicate sunspot activity.  If we assume that
(depending partly on latitude) the Sun takes a little less than 28
days (approximately 27.5 days) for a single revolution relative to
Earth, and there are 12 longitudinal sectors displayed, each one
represents about 2.29 days, or about 55 hours.  This can help you
make a rough estimate of how long it takes an area on the far side
to rotate across the horizon, which is at 90 degrees.
Currently three sunspot groups (numbered 1216, 1222 and 1223) are
visible, and another may be emerging.
Somehow a month ago I missed this announcement about the solar flux
and geophysical announcements on WWV going away.  Beginning
September 6, there will be no more announcements at 18 minutes after
the hour with solar flux, K and A index.  This was reported on the
League website at
Jeff Hartley, N8II of Shepherdstown, West Virginia sent a report on
May 23:  "There's not much of an exciting nature to report except
that 15M openings to EU seem pretty commonplace up to at least 22Z
with very good signals despite being well after dark (except in far
western and NW EU), despite the lower flux which was 85 today, 5-23.
Saturday 5-21, there was plenty of activity thru the day in the EA
King of Spain and UN DX contests on 15M from 13Z when I turned on
the radio.  There was the expected weakening of signals around noon
and then strengths increasing from 19Z thru the early evening.  EU
signals on 20 were weak in the morning which was pretty much
expected due to the shift to summer conditions and increased
absorption.  Around 1330-1430Z signals were good on 20 from JA
across to Kazakhstan which was more active than usual with the UN DX
Contest.  Around 24Z, I again was active on 20 most of the time
until 03Z with best signals from UN in the 24Z hour and conditions
gradually improved farther west with northern EU such as LY, SM, OH
and EU Russians workable all with good signals, but some very
fluttery.  Between the EU and AS Russians and UN's, I was pretty
busy running stations from 02-03Z working a total of 15 UN regions
for the day (almost every station is in a different region).  There
was sporadic E to the upper Midwest on Sunday around 01Z with one
loud signal from EN32 in IA on 6M and several on 10M.  12M is still
frequently open to the south including Caribbean thru much of the
day starting around 15Z".
Jon Pollock, K0ZN of DeSoto, Kansas (EM28) sent this in on May 21:
"The upper HF bands were excellent last night.  I worked a bunch of
Russian and European DX on 17 M between 10PM and Midnight.  The
interesting part was 15 M.  At 11PM CDT, I tuned the band and found
3 groups of digital signals around 21.070.  Obviously, I have no
idea what or who, but they were pretty strong.  So I tuned up in to
the phone band, this is now about 11:15 PM and heard a 'local' rag
chew between a couple of W4's and a W5.  It sounded like
backscatter.  Then I heard K0FPL in Kansas City chatting with AB0RJ
in St. Louis via 250 mile back scatter path.
I read the mail on their QSO, but no other signals on the band. It
sounded very dead.  Then I heard a 'break', someone wanting to break
into their QSO.  It was a strong signal so I figured someone local.
NOT!  It was E51CG in the Cook Islands!  Holy Toledo!  The Western
Pacific!  By now it was well after 11 PM CDT.
Another case of 15 M being 'dead' in the middle of the night.  The
E51 guy chatted with them for about 10 minutes and gave the locals,
10 db over S-9 reports in Raratonga, Cook Islands!
Trust me, the sunspots are back.  Several guys have been commenting
that they have not heard propagation like this in years and years.
Could we be lucky enough to have another really big sunspot peak?

I worked a KL7 in Western Alaska at 11 PM CDT on 15 M CW last night.
THAT is crazy stuff compared to what we been seeing for years.
Maybe after that crazy long multi year cycle low, we are going to
get a good one."
If you would like to make a comment or have a tip for our readers,
email the author at,
For more information concerning radio propagation, see the ARRL
Technical Information Service at  For an explanation of
the numbers used in this bulletin, see  An archive of
past propagation bulletins is at  Find more good
information and tutorials on propagation at
Monthly propagation charts between four USA regions and twelve
overseas locations are at
Instructions for starting or ending email distribution of ARRL
bulletins are at
Sunspot numbers for May 19 through 25 were 36, 33, 44, 47, 37, 23,
and 23, with a mean of 34.7. 10.7 cm flux was 84.4, 83.7, 83.6,
84.5, 84.1, 81.7, and 80.3, with a mean of 83.2.  Estimated
planetary A indices were 4, 3, 4, 4, 4, 6, and 4, with a mean of
4.1.  Estimated mid-latitude A indices were 2, 2, 4, 3, 4, 5, and
2, with a mean of 3.1.


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