ARRL Propagation Bulletin ARLP026 (2007)

ARLP026 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 26  ARLP026
From Tad Cook, K7RA
Seattle, WA  June 22, 2007
To all radio amateurs 

ARLP026 Propagation de K7RA

June 23-24 is ARRL Field Day, and it follows a week with no
sunspots.  As expected, there was a mild geomagnetic upset on
Thursday, June 21 when a solar wind stream pushed against Earth's
magnetic field.  The planetary A index went to 14, a moderate level,
but the mid-latitude A index, which affects most of us more
directly, was only 8.  That number comes from the Fredericksburg
Geomagnetic Center near Corbin, Virginia, which is at 38.2 degrees
north latitude.  Boulder, Colorado provides the mid-latitude A index
that we hear on WWV at 18 minutes after each hour, and at 40 degrees
north latitude, it produced an A index of 12 for June 21.

For the weekend, we might see another sunspot appear by Sunday, so
it looks like any 10-meter propagation will be sporadic-E skip, not
any great openings based on a higher MUF.  The predicted planetary A
index for June 22-24, Friday through Sunday, is 15, 10 and 8.
Predicted solar flux is 68, 68 and 70.  A solar flux value below 70
implies no sunspots, which you can observe alongside zero sunspot
days at,

Geophysical Institute Prague predicts unsettled to active conditions
June 22, unsettled June 23, and quiet June 24-25, quiet to unsettled
June 26, and back to quiet June 27-28.

The A index and solar flux predictions referenced in the previous
paragraph are available at,  After 2100z on
Friday, check this again for a June 22 update.

For visualizing propagation on each HF band for this weekend, try
VOAProp, mentioned in Propagation Forecast ARLP008 for this year
(see,  You can get the program free at, from G4ILO, the author.  This is a
program for visualizing worldwide propagation, and of course the
Field Day focus is on the United States and Canada.  

Field Day is also an operating activity that doesn't give any extra
points or multipliers for states, sections, DX countries, or zones,
so the operator just wants to work as many stations as possible.  DX
stations can be worked as well, but score the same as contacting a
station just down the road.

The program uses the predicted smoothed sunspot number, which
according to the software is currently 12, but if you wish, you
could try backing it down toward zero, as there have been no
sunspots lately.  Because it actually uses the prediction engine
from VOACAP, it gives only a monthly prediction, not one keyed to a
particular day of the season.

An alternative would be to use W6ELprop, which gives you an
hour-by-hour table of predicted relative signal strengths between
any two points for a particular day, although the variation from one
day to the next is hardly noticeable.  W6ELprop is free at,

With VOAProp, I can set up the station location for anywhere, and if
I set it for 0600z for Memphis, Tennessee, for instance, I can click
through the bands and see that 40-meters gives me the best coverage
over North America overnight.  I can select 15-meters and progress
the time through the day, and see that after sunrise, there is a
possibility of 15-meter openings, but it looks spotty.  At 1900z,
I'm seeing some propagation, but south toward Central America.

We received some reports of 6-meter openings on Father's Day, June
17.  Jim Henderson, KF7E of Arizona (DM43) said, "Central America
was booming," and he worked three that were new for him; Costa Rica,
Panama and Nicaragua.  Jim said the Central America opening lasted
for two hours, then many Mexican stations were heard and worked.
Later in the day there was a "pipeline" to the San Diego area
lasting 3-4 hours, and backscatter as well, which had him copying
K7ICW in Las Cruces (near El Paso) for an hour.

Also on Sunday another Arizona station, N7NRA, Glenn Stewart
reported a great 10-meter opening around 1800 local time (0100z
Monday) when stations from Florida, Missouri, Arkansas, Texas,
Oklahoma, California, Colorado, New Mexico, Nevada and Oregon
checked into the local 10-meter net.  On Saturday, the day prior,
Terry Oldham, KH6MT of Grand Island, Florida said he heard lots of
north-south propagation on 10-meters, and the next day had a solid
opening to Texas for two hours.

Ken Tata, K1KT of Warwick, Rhode Island reported a 6-meter opening
the following day (Monday) to VO1DJT from 1800z until at least
1820z.  He heard stations from 8 and 9-land calling the VO1, but
that may have been backscatter.  VO1DJT is way up in Lewisporte,
Newfoundland and Labrador, above 49.2 degrees north latitude.

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 a detailed
explanation of the numbers used in this bulletin see, An archive of past
propagation bulletins is at, .
Monthly propagation charts between four USA regions and twelve
overseas locations are at,

Sunspot numbers for June 14 through 20 were 0, 0, 0, 0, 0, 0 and 0
with a mean of 0. 10.7 cm flux was 68.5, 69.1, 68, 66.7, 66.6, 66.4,
and 65.7, with a mean of 67.3. Estimated planetary A indices were
20, 8, 7, 6, 5, 7 and 4 with a mean of 8.1. Estimated mid-latitude A
indices were 13, 7, 4, 3, 5, 5 and 2, with a mean of 5.6.