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ARRL Propagation Bulletin ARLP004 (2007)

ARLP004 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 4  ARLP004
From Tad Cook, K7RA
Seattle, WA  January 26, 2007
To all radio amateurs 

ARLP004 Propagation de K7RA

This week (January 18-24) saw lower sunspot numbers (seven points
lower, on average) than the previous week. Geomagnetic numbers were
also lower, especially the past few days. January 22 through the
first hours of today (January 26) at all latitudes had K index
readings of 0 or 1.

Low geomagnetic activity will be good for this weekend's CQ World
Wide 160-Meter CW Contest. But there is currently a flare-spewing
sunspot just around the Sun's eastern limb, and when it swings into
view we'll see solar flux about 10 points higher than now, and
briefly some higher geomagnetic numbers. The planetary A index for
January 26-31 is predicted at 5, 5, 15, 20, 20 and 15.

Geophysical Institute Prague predicts quiet conditions for January
26-27, unsettled January 28, unsettled to active January 29-30,
unsettled January 31, and quiet to unsettled February 1.

Bob McQuarrie, ZL3TY writes that while we have perhaps had a
not-so-great winter season for VHF E-skip in the Northern
Hemisphere, down in the Southern Hemisphere they are having a
wonderful spring and summer E-season, and comments "the best
experienced in many years." His reports are from over a month ago,
but last week he said "the good conditions continue."

Bob writes, "The 6m Sporadic E openings this summer have been the
best I have experienced in the past 18 years of operating on the
band. All mainland VK call areas have been worked and there have
been many prolonged openings into VK6 and VK8. The band has been
open to some part of VK every day since mid December."

He continues, "On the morning of 17 November, while operating meteor
scatter tests to VK, 2m opened to VK2 briefly and 3 Sydney stations
were worked."

Bob goes on to say, "The next 2m tropo opening started here at
1105am on Sunday 10 December with a QSO with VK2GKA, then the band
remained open until late Monday night. On Sunday I had SSB/CW QSOs
with 11 VK2s and 5 VK3s, also digital (JT65b) QSOs with 6 VK3s, on
Monday the opening continued with SSB/CW QSOs with 15 VK2s, and 3
VK4s and a digital QSO with VK4WS. On Sunday I had several 70cm QSOs
with VK2FZ."

He ends with, "On Saturday 23 December there was an excellent
Sporadic E opening starting at 911am NZT which lasted until 1145am.
Stations worked included 11 VK2s, 3 VK1s and 3 VK7s. Conditions were
so good an easy QSO was had with VK7HSE who was running 50W to a 1/4
wave GP antenna."

Thanks, Bob.

Thanks also to N0AX's ARRL Contest Rate Sheet and N2IC for this tip.
Go to the Meteorology and Training web site at, for some wonderful online
training on space weather. You will need the Adobe Flash Player from if you don't already have it. These courses
are wonderfully illustrated and animated, and free.

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 January 18 through 24 were 23, 15, 31, 18, 23,
18 and 15 with a mean of 20.4. 10.7 cm flux was 76.8, 76.3, 78.8,
78.6, 78.5, 79.3, and 80.4, with a mean of 78.4. Estimated planetary
A indices were 16, 11, 7, 7, 3, 2 and 1 with a mean of 6.7.
Estimated mid-latitude A indices were 9, 9, 6, 7, 2, 3 and 1, with a
mean of 5.3.


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