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ARRL Propagation Bulletin ARLP012 (2015)

ARLP012 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 12  ARLP012
From Tad Cook, K7RA
Seattle, WA  March 20, 2015
To all radio amateurs 

ARLP012 Propagation de K7RA

The Spring Equinox is today, March 20 at 2245 UTC.

On Tuesday, March 17 a CME struck Earth producing the largest
geomagnetic storm of the current solar cycle. Aurora was visible all
the way down to the central United States. The planetary A index for
the day was 117, an incredibly high number. It looks like the
greatest impact was in the second half of the UTC day, when the
planetary K index in the four 3-hour periods was 8, 8, 7 and 8.

Average daily sunspot number for this week rose from 32 to 59.1, and
average daily solar flux declined from 127.8 to 114.8.

The latest prediction has solar flux at 110 on March 20, 105 on
March 21-22, 100 on March 23-26, 105 on March 27, 110 on March 28,
105 on March 29-31 and 110 on April 1. Flux values are expected to
reach a peak of 120 (which is not very high) on April 3-5, and a low
of 95 on April 17-18.

Predicted planetary A index is expected at 18 and 8 on March 20-21,
20 on March 22-23, 10 on March 24, 5 on March 25-26, then 15, 30 and
25 on March 27-29, then 12, 10 and 8 on March 30 through April 1,
and 10, 15 and 12 on April 2-4 and 5 on April 5-6.

Petr Kolman, OK1MGW of the Czech Propagation Interest Group expects
geomagnetic conditions to be mostly quiet on March 20, quiet to
unsettled March 21, quiet to active March 22, active to disturbed
March 23, quiet to unsettled March 24, mostly quiet March 25-26,
quiet to unsettled March 27, active to disturbed March 28-29, quiet
to unsettled March 30 through April 2, quiet to active April 3,
quiet to unsettled April 4-5, quiet on April 6, mostly quiet April
7-10, quiet to unsettled April 11-12, quiet to active April 13-14,
and quiet to unsettled April 15.

The planetary A index at 117 was huge, but when was it last that

Here is a list of dates when the planetary A index was above 100, in
reverse order, along with links to the propagation bulletin
reporting it:

12/15/2006 Ap=104

Notice in the above bulletin is a link to a December 21, 2006
article claiming that the next solar cycle might be the biggest
ever. Oh, if only that were true. Cycle 24 was one of the weakest on
record, peaking about a year ago instead of 2010 or 2011 as forecast
in that article.

9/11/2005  Ap=105

8/24/2005  Ap=110

5/15/2005  Ap=105

11/8/2004 to 11/10/2004  Ap = 189, 120, 181.

The two STEREO observatories are very close to each other right now.
In fact, they will be practically on top of each other early
Saturday morning, North American time between 1249 and 1318 UTC when
their separation is only .023 degrees.

You can see the latest solar images from this project at .

Andy Fugard, M0INF hadn't heard anything on 10 meters before March
7-8 and using an indoor magnetic loop antenna he worked KI1G, W3LPL,
9A1P, YU1EW, N1UR, AA1K, NC1I and LZ4TX from his apartment in
London. You can see the antenna hanging in his window on his

We had another report about those same dates from Francesco Basta,
PE1F. He wrote, "I read your column yesterday and was particularly
interested in your note about a solar flare that could cause
exceptional propagation conditions at frequencies above 10 MHz. I
think I can offer a witness about what happened on 28 MHz.

"I am located in Utrecht (Netherlands), JO22mc. I have some problems
with my antenna these days, so I can only use a small internal
antenna next to a window that covers 28, 50, 144 and 430 MHz bands.
With such an antenna I don't dare to use the full power of my
FT-950, so I used rather an FT-817 (5 W). I am located on the ground

"Since about 1030 UTC on March 7 I started hearing weak stations
from South America on 10 meters, namely Brazil, like the beacons
PY2WFG on 28.203 MHz and PT2SSB/B on 28.210 MHz. At about the same
time I could also hear beacons closer to me, like YM7KK/B (from
KN90iv) on 28.220 MHz and YM7TEN/B (from KN91rb) on 28.225 MHz

"In the evening I tried to have some QSOs with the US during the
ARRL contest, and indeed I managed to work K1KI from Connecticut
(1741 UT), W2IRT from NJ (1753 UT) and XL3T from Ontario (1806 UT).
Not bad for 5 W and an internal antenna...

"But the really incredible QSO happened the following day, March
8th, at 1706 UT: RI1ANR on CW from Antarctica on 28.004 MHz! And I
even managed to pass at the third or fourth attempt.

"Finally, I could hear an FM repeater from New York on 29.620 MHz
after about 30 minutes, at S9!

"It was really a wonderful experience, which I could not explain
until I read your article on"

Tyler Suydam, KC2LST of Parsippany, New Jersey wrote, "A couple of
anecdotes from last Saturday's M-class flare, which I didn't know
had occurred until after the ARRL DX SSB contest ended. On Saturday
night around midnight US east coast time, I worked two stations in
Hawaii on 40M phone, which I had never done before in my 8 years of
being active on HF with my low dipoles. However, that day and the
next, I was unable to hear, let alone work, any stations in Alaska
or Japan on any HF band, which I have been able to do regularly
during this 'peak' period of the current solar cycle. So from my
locale, it seemed the attenuating effect was confined to the Pacific
Rim, or at least did not affect the Hawaiian Islands. It would be
interesting to know whether stations there noticed unusual
propagation conditions as a result of the flare."

Mike Carter, K8CN of Durham, New Hampshire wrote on March 17, "I
just read in the news of the level 4 geomagnetic storm that reached
Earth earlier today (10 AM EDT by the news account). I hadn't been
active on the bands for the past several weeks due to a death in the
family, but was on the 20, 30, 40, and 80 meter bands over the past
24 hours and noticed unusually good propagation to areas that had
several weeks ago produced noticeably weaker signals. I run strictly
QRP CW, but was able to easily work E51 and VK on 30 meters
yesterday around 1045Z, and easily worked VK again this morning on
40 meters about the same time. Last night (about 0230Z) I heard
strongly, but couldn't break the pileups, E30FB and 9Q0HX on 20
meters. To my amazement I copied but did not work FK8 and RW0 on 80
meters around 1030Z this morning. Both were weak, but copyable, and
the pileups built quickly.

"I know that the Vernal Equinox provides enhanced HF propagation,
especially along the gray line, and no doubt the openings I cited
may be just due to this phenomenon. I am curious if the outer edges
of the geomagnetic storm that arrived today might have actually
enhanced HF propagation prior to the main blast's arrival, or is
that not possible?"

Rich Zwirko, K1HTV wrote, "March 17, 2015, St. Patrick's Day, was a
memorable one for VHF DXers. With the K Index between 7 and 8 we
were treated to some nice propagation via aurora. From my
Amissville, VA QTH, on 144 MHz, I heard or worked stations as far
east as Maine and as far west as Iowa including:

2037 K9MRI   IN EN70 
2107 WB8AUK  OH EN90 
2043 W9ZIH   IL EN51
2107 W9EWZ   WI EN52 
2128 VE3VHB  ON FN24 
2146 KC0CF   IA EN32  (Best 2M DX this aurora, 867 miles. Also heard K0KD in EN31, but he
got away.) 
2155 VE3ZV   ON EN93 (on SSB) 
2222 W9JN    WI EN54 
2232 KF6A    MI EN73

"At 2059 UTC the aurora was intense enough to reflect signals
between W9ZIH (IL EN51) and K1HTV (FM18ap) for my first ever 432 MHz
aurora QSO."

Quite impressive. That is 617 miles on 432 MHz.

Many people emailed me the call sign for Bob MacKenzie, mentioned on last week, and I heard from him via email a couple
of days later. He is VA3RKM. He wrote, "A friend of mine, Jose
VA3PCJ, mentioned to me that it was interesting that I worked three
amateur stations in Japan between 2233 and 2240 UTC on March 7, 2015
on the 10 metre band (28.4 MHz) only minutes after the M9 flare with
just 5 watts of single-sideband power and a single-element vertical
antenna in my backyard. It's a rare event to work Japan so easily
with such little power on phone and not Morse code. The annual ARRL
International DX Phone contest was on at the time so there were
plenty of DX stations on the air, making this observation of unusual
propagation possible.

"My station is located in Ottawa, Canada (see under VA3RKM).
We were wondering about propagation paths to here. The first contact
with Japan (JA0JHA in Niigata, according to required a few
repeats and the next two (JA0QNJ also in Niigata; JA7OWD in
Haramachi Hukushima, Fukushima? according to were
remarkably easy."

Jon Jones, N0JK wrote, "Regarding the report that
solar flares can be 'good and bad for radio communications' I was
operating on 50 MHz from the south tip of Maui on March 11 around
0000z. I heard LW3EX (GF05) calling CQ on 50.096 MHz CW. I called
and got a reply, then Walt faded out as a M-Class solar flare
occurred from AR2297. Fortunately the adverse effects of the solar
flare were brief, and Walt reappeared with a stronger signal and we
were able to complete a contact about 10 minutes later. I was mobile
with a 1/4 wave whip antenna. 12,000 km from Hawaii to Argentina."

Chris Parker, AF6PX of Torrance, California wrote, "I fly a
Bombardier Challenger biz jet with two very expensive Rockwell
Collins HF9000 radios for long-range aeronautical communications.
Turns out they also work great for amateur band aeronautical mobile
use. With 150W PEP, and an antenna at 41,000 feet, it's virtually
impossible that I can't work anyone I can hear. Except Tuesday,
March 17th. On that day, on a flight from Arizona to the San
Francisco Bay area, I tuned across the 20M, 17M, and 15M bands and
didn't hear a soul. I knew something was up; but I didn't know what
until I watched the evening news. That's when I found out that a
powerful CME had impacted the Earth and caused a disruptive
geomagnetic storm. I sure hope this settles down quickly, because I
can't wait to get back to my aeronautical mobile DX!"

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

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 12 through 18 were 56, 87, 56, 54, 57, 60,
and 44, with a mean of 59.1. 10.7 cm flux was 126.7, 119.4, 115.6,
114.4, 117.2, 114.3, and 114.8, with a mean of 117.5. Estimated
planetary A indices were 8, 6, 5, 7, 11, 117, and 52, with a mean of
29.4. Estimated mid-latitude A indices were 6, 5, 5, 7, 9, 46, and
32, with a mean of 15.7.


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