Secure Site Login

ARRL Propagation Bulletin ARLP015 (2015)

ARLP015 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 15  ARLP015
From Tad Cook, K7RA
Seattle, WA  April 10, 2015
To all radio amateurs 

ARLP015 Propagation de K7RA

Solar activity continues to weaken.  Average daily sunspot numbers
dropped 27.8 points to 50.1 on April 2 to 8, compared to the previous
seven days.  Average daily solar flux declined 17.3 points to 118.4
over the same period.
The latest prediction has solar flux at 115 on April 10 to 16, 110
on April 17, 145 on April 18 and 19, 135 on April 20, 130 on April
21 and 22, 125 on April 23, 120 on April 24, and 125 on April 25 and
26.  Solar flux goes down to 115 on April 30 through May 2, then
rises to 145 on May 7 to 10.
The same prediction has planetary A index at 15 and 8 on April 10
and 11, 5 on April 12 to 16, 12 on April 17, 20 on April 18 and 19,
12 on April 20 and 21, 8 on April 22 to 24, 25 on April 25, 29 on
April 26 and 27, then 15, 12, 18 and 12 on April 28 through May 1,
and 8 on May 2 and 3.
These predictions are revised daily, and come from 45-day forecasts
at . I am also now
making available my archives of these predictions, with planetary A
index at 
and solar flux at . 
These are Microsoft Excel spreadsheets, and if you don't have that 
program, you can download a free Excel Viewer at .
I hope to update these as often as once daily. You will see how the
solar flux forecasts have been weakening over time.
OK1HH predicts the geomagnetic field will be mostly quiet April 10
to 12, active to disturbed April 13, disturbed April 14, active to
disturbed April 15, quiet to active April 16, active to disturbed
April 17, quiet to unsettled April 18, quiet to active April 19,
quiet on April 20, quiet to unsettled April 21, mostly quiet April
22, quiet to unsettled April 23, mostly quiet April 24, quiet to
active April 25 and 26, quiet April 27, mostly quiet April 28,
active to disturbed April 29, and quiet to unsettled April 30
through May 1.
At 2346 UTC on April 8, Australia's IPS Radio and Space Services
issued a geomagnetic disturbance warning for April 9 and 10, due to
a CME and solar wind from a coronal hole.  Geomagnetic conditions
may be at active levels over the two days.
The Japan International CW DX Contest is this weekend. Check it out
at .
Rich Zwirko, K1HTV wrote, "Despite the relatively low solar flux
number in the low 100's there is still life in the higher HF bands.
In the past few days conditions to deep Asia have been excellent. On
Tuesday morning April 7th, with 100 Watts and a wire antenna from my
VA QTH, I worked HS0LSE and heard E21EJC, both in Thailand on 12
meter CW. I moved to 15 meters and in less than an hour, with 100
watts and a triband yagi I was able to work:
CW  - V85TL - Brunei 
SSB - HS1JNB - Thailand 
SSB - AT150ITU - India (special call) 
CW  - HS3XVP - Thailand 
SSB - HS0ZIN - Thailand 
SSB - HS0ZLE - Thailand 
SSB - VU2DED - India 
Other stations heard coming through included 9M2MSL, DU1/JA3FJE,
XU7TZG on SSB and XV5HS on RTTY. The polar path was great between
1530 and 1630Z that day. The next morning, April 8th, I was only
able to get down to the shack for a half hour. Between 1400 and
1430Z I worked three more stations in Thailand, E21EJC on 12M as
well as HS4ROI and HS0ZCW on 15M SSB. Conditions were so good that
CO2IR in Cuba, running QRP 10 Watts, worked HS0ZCW in Thailand.
Later that afternoon I was able to work all 6 continents in 30
As UTC April 9th started, at 0001Z on 20M CW I snagged JT1AA/5 plus
a number of Asiatic Russian stations. Fifteen hours later JT1AA/5 in
Mongolia with a booming signal was worked again, this time on 15
Around the vernal equinox, despite the low SFI numbers, with
relatively low 'A' and 'K' indexes, conditions over the polar routes
can be great.
Enjoy the DX while the conditions are good as we are now on the
downward slope of this solar cycle."
On April 8, Scott Bidstrup, TI3/W7RI wrote: "Don't know if you have
seen this yet, but in case you haven't, it's some new research that
suggests that the sun has 'seasons' of about two years that affect
the activity within a solar cycle:
Ted Leaf, K6HI reported a similar article:
I also found this:
TI3/W7RI continues:
Not a lot to report here on HF propagation; haven't been on HF much
due to health issues, and only getting on six meters when the
squelch breaks. But there has been a bit of activity on six.
Six meters has been showing the usual equinox-related TEP activity
here in the low magnetic latitudes, with nightly openings into South
America from here in Costa Rica and the Caribbean.  There have been
no Es openings into the States for quite some time from here, but
the last several days have seen some afternoon TEP openings from the
States into South America, as usual going right over our heads, but
with nothing to show for it here on the ground. With the fellas in
the States reporting S9+30 signals, there hasn't been even a trace
on the waterfall here.
There was a spectacular F2 opening into Iberia and northwest Africa
a couple of weeks ago from here, and many of us got several new ones
during an opening that lasted several hours. It was my first success
in working Europe from here with my modest 90 watts and a 5/8
vertical, and I got four new countries in just one opening. Towards
the end of the opening, I nailed Western Sahara for an all-time new
one (never expected that to happen on 6 meters!), as did Mike,
TI5XP. Phil, TI5/N5BEK heard him, but wasn't able to complete a Q
before he was gone into the noise. The 'tragic' band strikes again!" reports that early today, April 10, a G2 Class
geomagnetic storm erupted.  "Northern Lights spilled across the
Canadian border into the USA, where auroras were photographed as far
south as Colorado. At the time of this alert, storm conditions are
still underway with a possibility for more storming when a belated
CME arrives later in the day. Visit for more
information and updates."
At I can see that the
first two of eight three hour periods today (April 10) have a
planetary K index of 5 and 6, which is high.
David Moore sends this article and image from Southern Iceland:
G3CJC has a weekly report on 10 meter activity from England:
He even has some sports commentary at the end on soccer, but over
there they call it football, just as the rest of the world does.
Mike Carter, K8CN of Durham, New Hampshire sent this article from
NBC about lightning:
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 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 April 2 through 8 were 31, 29, 68, 66, 78, 39,
and 40, with a mean of 50.1.  10.7 cm flux was 121.3, 119.9, 122.4,
122.2, 125.6, 111.2, and 106, with a mean of 118.4.  Estimated
planetary A indices were 13, 14, 12, 8, 7, 5, and 4, with a mean of
9. Estimated mid- latitude A indices were 22, 14, 10, 8, 8, 6, and
4, with a mean of 10.3.