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ARRL Propagation Bulletin ARLP041 (2005)

ARLP041 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 41  ARLP041
From Tad Cook, K7RA
Seattle, WA  September 30, 2005
To all radio amateurs 

ARLP041 Propagation de K7RA

Average daily sunspot numbers dropped over the past week by over 16
points to 29.7. Solar flux values were down 20 points to 80.2. The
week was quiet, with no geomagnetic storms. September 26-28 had the
most geomagnetic activity, but it was all pretty mild. The K index
for middle latitude and planetary readings only went to 3 or 4 on
occasion and quickly dropped back to 2.

The forecast for the next few days, September 30 to October 2, is
for low sunspot activity. The next peak of activity may be when
sunspot 798 returns, currently on the Sun's far side. That activity
should peak around October 14-16. The geomagnetic prediction for
this weekend is for mild to unsettled conditions, with the planetary
A index for September 30 through October 3 at 15, 15, 12 and 12.
Prague Geophysical Institute predicts quiet conditions for October 5
and 6, quiet to unsettled conditions October 3 and 4, and unsettled
conditions September 30 through October 2.

Brandon Duke, KC0UWS says he is still working 10 meters successfully
from Colorado into South America, with only 25 watts and an indoor
isoloop in his apartment. Around September 20-23 he worked Brazil,
Belize, Costa Rica and Argentina among others, all with S8 signal
reports. 15 meters is still good as well, and open more often than
10 meters. Doing a path projection from Dallas, Texas to Brazil over
this weekend with a sunspot number of only 22 shows 15 meters
opening strongly from 1530-2300z. Signal strengths should be better
toward the end of that period.

The West Coast also looks good, with 15 meters probably open from
1630-2400z toward Brazil from Seattle. Move east though, and the
opening tightens a bit. From Cleveland, the opening isn't as strong
and probably only runs from 1630-2000z.

Allan Greening, VK3PA said he has worked 250 countries on 80 meters
from Australia over the past three years. You can see his notes on
DX worked at,

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 and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
bulletins is found at,

Sunspot numbers for September 22 through 28 were 28, 49, 33, 28, 25,
23 and 22 with a mean of 29.7. 10.7 cm flux was 83.7, 82.8, 81.4,
81, 81.3, 76.9, and 74.6, with a mean of 80.2. Estimated planetary A
indices were 8, 8, 4, 5, 14, 13 and 12 with a mean of 9.1.
Estimated mid-latitude A indices were 6, 5, 2, 3, 9, 10 and 12, with
a mean of 6.7.


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