QST de W1AW
Propagation Forecast Bulletin 26 ARLP026
>From Tad Cook, K7RA
Seattle, WA June 24, 2005
To all radio amateurs
SB PROP ARL ARLP026
ARLP026 Propagation de K7RA
First the outlook for ARRL Field Day, which is this weekend, June
A projection from early Thursday from Geophysical Institute Prague,
Geomagnetic Department, shows active geomagnetic conditions on
Friday, June 24, followed by unsettled to active on June 25-26.
This is from an early Thursday morning prediction.
Thursday afternoon Air Force Space Weather Operations predicted a
planetary geomagnetic A index of 20 for each of those same three
days. They've predicted a planetary A index of 20 for Saturday and
Sunday since June 7. Prior to that they predicted values of 18 for
Saturday and 20 for Sunday. These aren't great conditions for HF,
but are not at the level of a geomagnetic storm like we had on
Thursday June 23 when the planetary K index went all the way to 7,
and the planetary A index was 48. Sunspot numbers and solar flux are
expected to remain low, with solar flux around 85.
This operating event gives no multipliers for DX or the number of
states or sections worked, so it isn't like a DX contest in which
poor conditions leading to no opening to Europe or Asia becomes a
bad thing. Given the low sunspot numbers, 20 and 40 meters are going
to be the best bands for working cross country, with 80 meters open
after dark. 40 and 80 should be the best bands for working stations
less than 1000 miles away, day or night.
To review the past week, sunspots and solar flux numbers were lower.
Average daily sunspot numbers dropped nearly 28 points from the
previous week to 51.1. Average daily solar flux was off over 15
points to 87.7. The big geomagnetic activity of note was one day
following our Thursday through Wednesday reporting period, on
Thursday, June 23, when the mid-latitude A index was 30 and
planetary A index was 48.
Markus Hansen, VE7CA in North Vancouver wrote with some propagation
observations on the longest day of the year, June 20. He notes that
southern West Coast stations (I assume California) were working East
Coast on 6 meters, but he heard nothing in British Columbia until
8-9 PM that evening, when he worked California on 6 meters. He
called CQ beaming West and Northwest to try to work KH6 or KH7, but
had no luck. He reports that on 10 meters the KH6WO beacon 'was
pounding in at S9+10-20 db.'
Markus says, 'Just after midnight I returned to have another listen
and there was no 6-meter activity, but 20 meters was wide open to
Europe and the South Pacific with many stations across the band. On
20 meters the OH2B beacon was a steady S9+20 dB and no arctic
flutter. Pointing to the Pacific, the W6WO, KH6WO, ZL6B, VK6RBP,
JA2IGY and VR2B beacons were all readable, some very strong. On 15
meters the KH6WO and ZL6B were still all readable both over S9 and
on 10 meters I was hearing KH6WO at between S5 - S2.'
He continues, 'I called CQ on both 15 and 10 meters but no answers.
Amazing. The longest day of the year sure can produce some very
Check out VE7CA's personal web page at,
Matthew Chambers, KC0QEV in Macon, Missouri reports nice 2 meter
tropospheric openings on June 21. With 10 watts PEP into a 7 element
antenna only 4 feet above the ground he worked Northern Michigan and
Arkansas from EM39. The stations he worked were in EN82 and EM36. A
neighbor of his running 300 watts on 2 meters into a pair of big
Yagis at 100 feet worked into Southern Texas and could hear stations
in Mexico. Matthew reminds us not to forget VHF for Field Day this
Roger Bonuchi, AC9Y from the Chicago area mentioned great 6 and 10
meter openings on June 17-18. He heard East Coast stations on both
bands when mobile at S9 and above, and worked a number of stations
on 10 meters. When he returned home, he used an attic mounted
horizontal loop on 6 meters to work many stations on CW and SSB.
His best was VE6TA in Edmonton via CW, where he received a 559
report. This was about 1500 miles from his QTH on Chicago's South
He also passes on an interesting resource, which he referred to as
'Hepburn's Tropo page.' This is a tool for predicting tropospheric
ducting based on weather patterns. Check it out at,
Bob Sluder, N0IS wrote about a fantastic opening to Hawaii on 6
meters from the Midwest. He's in Imperial, Missouri, and said the
opening to KH6 did not last long that evening, but he heard many
beacons from the west, and could still hear them Thursday morning at
One last note about Field Day propagation. As I'm finishing this
after 0800z on Friday, I noticed that the IMF (Interplanetary
Magnetic Field) is now pointing south, which is not what we would
like. Earlier it was pointing north, which better protects Earth
from solar wind. Perhaps it will change direction again before
If you would like to comment or have a tip, email the author at,
For more information concerning radio propagation and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at,
www.arrl.org/tis/info/propagation.html. An archive of past
bulletins is found at, www.arrl.org/w1aw/prop/.
Sunspot numbers for June 16 through 22 were 67, 59, 50, 43, 47, 53
and 39 with a mean of 51.1. 10.7 cm flux was 98.1, 90.8, 90, 86.9,
86.1, 82.8 and 79.5, with a mean of 87.7. Estimated planetary A
indices were 26, 14, 7, 7, 5, 4 and 7 with a mean of 10. Estimated
mid-latitude A indices were 19, 9, 5, 3, 2, 1 and 6, with a mean of
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