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ARRL Propagation Bulletin ARLP011 (2016)

ARLP011 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 11  ARLP011
From Tad Cook, K7RA
Seattle, WA  March 11, 2016
To all radio amateurs 

ARLP011 Propagation de K7RA

Average daily sunspot numbers and solar flux both increased over the
past week. Average daily solar flux went from 92.9 to 96.8, and the
average daily sunspot number from 41.4 to 64.4. Geomagnetic
indicators increased, with the most activity on March 6 and 7.

On March 6-7 the planetary A index was 35 and 24.  According to this was caused by a CIR. On March 4 they wrote,
"NOAA forecasters estimate a 50% chance of polar geomagnetic storms
on March 6th when a co-rotating interaction region (CIR) is expected
to hit Earth's magnetic field. CIRs are transition zones between
fast and slow-moving solar wind streams. Solar wind plasma piles up
in these regions, producing density gradients and shock waves that
do a good job of sparking auroras." also mentioned that the Spring Equinox (Sunday,
March 20 at 0430 UTC) is a time for enhanced aurora activity. The
weeks around equinoxes (both Autumnal and Vernal) are a time of
increased aurora borealis. 6 meter operators will want to be alert.

On March 6 reported a G-2 Class geomagnetic storm.
(Go to and click on
the Geomagnetic Storms tab for details). G-2 signals a moderate
geomagnetic storm, and typically "HF radio propagation can fade at
higher latitudes, and aurora has been seen as low as New York and

Predicted solar flux is 95 on March 11-13, 90 on March 14-17, 95 on
March 18-20, 90 on March 21-23, and 95 on March 24-30. Solar flux
then continues to meander between 90 and 95 for the remained of the
45 day forecast.

Predicted planetary A index is 5 and 10, on March 11-12, 8 on March
13-14, 5 on March 15, 30 and 24 on March 16-17, 25 on March 18-19,
12 on March 20, then 5 on March 21 through April 2, then 22, 10 and
8 on April 3-5 and 5 on April 6-7. The planetary A index then
increases to 25 again on April 13-15.

F.K. Janda, OK1HH expects geomagnetic conditions to be quiet to
unsettled March 11-12, quiet to active March 13, active to disturbed
on March 14-16 (although the March 15-16 period is less likely),
quiet to active March 17, mostly quiet March 18-19, quiet on March
20-21, mostly quiet March 22, quiet again on March 23, mostly quiet
March 24, quiet in March 25-27, quiet to active March 28, quiet to
unsettled March 29-30, mostly quiet March 31, quiet on April 1-2,
active to disturbed April 3-4, quiet to active April 5 and mostly
quiet April 6.

OK1HH expects increases in solar wind on March 14-17 and again on
March 30 to April 4, but the outlook for increased solar wind is
less certain for March 30-31.

On March 8, Dr. Jon Jones, N0JK (editor, The World Above 50 MHz in
QST) of Lawrence, Kansas wrote:

"Did not expect a lot on 10 meters Sunday morning of the ARRL DX SSB
contest with solar flux around 100. But conditions were remarkable
in eastern Kansas.

"Starting at 1707z with EI4KF, worked scads of Europeans. Many
eastern Europeans were loud, along with Africa. The best DX was
FH/IK5ZUI and ES5Q. 5D3A and HB9AUS were 20 over S9. I was 'fixed
mobile' on a hill top just west of Lawrence, antenna a 1/4 wave whip
for 10 meters with a MFJ tri-magnet mount on the roof of the car."

KC0DEB, also in Kansas noted, "It was pretty neat to see how
propagation moved on 10 meters, from North Africa through Central
and Eastern Europe to the Baltics and back down again to Southern
France and Spain. Not all signals were strong, but the majority were
Q5. 9A1A (Croatia) was one of the loudest ones I heard here from EU
on 10m though. I think it was Paul N4PN behind the mic, pegging the
S-meter at 9+40dB! Unbelievable!

"Around 1800z I noted aurora polar flutter on SK3W and ES5Q and
considerable QSB on many Europeans. HB9AUS was solid and very loud.
There was a geomagnetic storm in progress at this time, with the Kp
peaking at 7."

On March 10, Jeff Hartley, N8II of Shepherdstown, West Virginia

"Well today was a great example of conditions falling well short of
the solar indices. All day long, the MUF on northern hemisphere
paths were low especially into EU and polar paths/northern EU were
almost closed. I heard nothing on 10M except for South America.
There were 'no storms' present or forecast all day from WWV and the
solar flux was pretty steady at 95 down from 97 Wednesday. Other
stations I worked agreed that conditions were poor as well. 15
meters seemed completely closed to EU at 1815Z vs. 10 meters open
well at same time Sunday.

"I was not very active in the ARRL DX SSB contest last weekend on
March 5 and 6, visiting Luray Caverns nearby with a friend on
Saturday; it really is quite a natural wonder.

"Friday evening sounded very good on all bands 15M working my way
down to 75M by 0245Z and QRT around 0320Z. JAs had good signals on
15M at the start with one booming Alaskan, Hawaiians and South
Americans, then 20 was pretty well open to all of EU except Russia
with very loud signals from even the northern Caribbean down into
SA. Some zone 18/19 Asiatic Russians and Alaska were loud as well.
40 was wide open to EU at 0130Z and the United Arab Emirates were
worked. EU signals were good on 75, but precip static crashes were
fairly high.

"Sunday was an excellent example of wonderful conditions that were
actually enhanced by an impending G3 level storm.  At 1513Z, I
finally returned to the radio to find 10 meters open well to EU,
working two Swedish stations in about the first 8 QSOs. I had a nice
run of EU callers for about a half hour until signals weakened from
most of the continent except Ireland, Italy, and the Balkans.  Most
signals were quite good strength including calls from Lithuania,
Latvia, Norway, Finland, Poland, Macedonia, and Kaliningrad.

"Following my run conditions turned quite strange on 10M with very
weak Spanish, German, and French stations obviously getting very
loud signals from the Midwest from OH to CO and even some W6/7s!

"Irish and some Brits/Welsh were still quite loud in the 1600Z hour.
The K index was 5 by 1800Z and 6 before the end of the contest.
Around 1730Z, conditions on 10 improved with loud signals from
Norway, Sweden, Finland, and Latvia as well as French and Italians.
A St. Petersburg station called me at 1811Z for first Russian of the
day. Most signals from northern EU did NOT have flutter, but some
from SW EU did!

"After a break, returning at 1950Z signals were loud from Spain and
Portugal well into their evening and signals from even as close as
Cuba were loud from the south with only moderate signals from
Brazil/Argentina due to the high MUF to the south. Sunday was quite
a celebration of 10 meters, a last gasp probably until the next
cycle. 15 was excellent to all of EU as well."

Thanks Jeff for your report.

We haven't heard from Martin McCormick, WB5AGZ in Stillwater,
Oklahoma in a very long time. But he contributed this on March 7:

"10 meters still has a bit of life left in it but the vital signs
are becoming less frequent.

"I have taken to leaving an FM receiver on 29.6 MHZ and recording
its output to catch anything interesting from a discone antenna up
about 50 feet.

"It does occasionally spring to life for very brief periods but
nothing like it was during past solar cycles or even in the Winter
of 2014.

"I live in almost the exact center of the contiguous United States
and Winter F2 usually brings us the extreme northeast down to about
New Jersey plus the extreme Northwest from roughly Canada to Central
California. One also hears the extreme Southeast, mostly Florida and
the Caribbean plus far southwest as in Hawaii and the South Pacific.

"If the F2 really gets going, the skip zone gets a bit larger and we
start hearing further inland all around but this F2 season has been
pretty spartan.

"The last two weeks have been a pretty good example, mostly dead
except for some openings on the low end of 10 meters and a couple of

"On Friday February 19, I began hearing a station in the first call
district calling CQ on 29.6 between 0900 and 1000 or so (local,
1500-1600 UTC) with fades from nothing to almost full quieting and
then it all died away.

"On Sunday March 6, I had forgotten the receiver was even on and
then about 1600 Central time, I heard a brief burst of carrier which
I first thought was a local station until there was another burst of
carrier which was on long enough to fade a bit.

"I next heard an unidentified station which faded in and then out
with what sounded like possibly an Australian accent but I never got
the call sign.

"Other partial QSOs were audible but not well enough to have
participated and then the pipeline opened up for listening with
KH6RC on the big island of Hawaii talking to a station in Santa
Rosa, California which I could never hear from here.

"The Hawaiian station ranged from almost full quieting to a closed
squelch but was what I would call a good copy.

"A few minutes later, it all vanished around 1700 Central time,
which is UTC-6 (2300 UTC). This is pretty typical of 10 meters when
conditions are marginal.

"F2 is only going to generally get worse as the solar activity
declines but in two more months, the Northern Hemisphere will be in
Summer sporadic-E season and that can open up at any time of the day
or night with lots of skip in the 400-800 mile range and cover
frequencies from 10 meters through 6 and sometimes even 2 meters and
222-225 MHZ.

"They don't call it sporadic-E for nothing. The VHF bands can be as
dead as a doornail one minute and then booming with signals the
next. Of course the next minute after that it may be back to dead
again so one must strike while the iron is hot!"

Here we go again with another scary story on the infamous and truly
frightening nineteenth century Carrington Event, this time from
regular contributor David Moore.

NOAA says (on March 11, 2016) that there is a less than 1% chance of
solar flares today. There are sunspots all over the Earth-facing
solar image, but with solar activity remaining low, there seems to
be little chance of any aurora or geomagnetic activity.

Steve Shorey wrote:

"Steve G3ZPS here near London UK

"I'm sure all those on the air noticed that HF conditions improved
spectacularly over the weekend of 5th and 6th March - FoF2 over 9MHz
in Europe and 10m open to West Coast US from UK. I'm sure the
contesters were happy!

"The Sunday improvement was just before the arrival of the predicted
Geomagnetic storm that triggered a G2 class storm and visible
auroras. I have noticed on more than occasion in the last year that
HF (and sometimes up to 6 meters) propagation improves markedly just
before the storms arrive.

"Of course the immediate aftermath is poor conditions for a few days
(FoF2 way down on Monday). Is there any known correlation between
the sudden uptick in HF conditions just prior to a geomagnetic
disturbance - e.g. is the F2 intensely ionized by some mechanism
just a few hours before?

"Regards from UK

Steve G3ZPS"

My response:

I suspect what was happening is outlined in this piece by K9LA:

The STORM model he references has moved to:

I will Cc K9LA and see what he thinks.

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 web page at, For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at More good
information and tutorials on propagation are at

My own archives of the NOAA/USAF daily 45 day forecast for solar
flux and planetary A index are in downloadable spreadsheet format at and .

Click on "Download this file" to download the archive, and ignore
the security warning about file format. Pop-up blockers may suppress
the download.

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 March 3 through 9 were 50, 95, 68, 68, 61, 48,
and 61, with a mean of 64.4. 10.7 cm flux was 98.7, 100.5, 96.2,
95.5, 94.1, 95.5, and 97.4, with a mean of 96.8. Estimated planetary
A indices were 8, 4, 4, 35, 24, 8, and 7, with a mean of 12.9.
Estimated mid-latitude A indices were 7, 2, 3, 19, 17, 6, and 6,
with a mean of 8.6.


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