ARRL

ARRL Propagation Bulletin ARLP023 (2001)

SB PROP @ ARL $ARLP023
ARLP023 Propagation de K7VVV

ZCZC AP23
QST de W1AW  
Propagation Forecast Bulletin 23  ARLP023
From Tad Cook, K7VVV
Seattle, WA  June 1, 2001
To all radio amateurs 

SB PROP ARL ARLP023
ARLP023 Propagation de K7VVV

Average daily sunspot numbers rose nearly 28 points and average
solar flux increased slightly over the past week. Solar flux peaked
on Thursday, May 24 at 170.3 and has been declining since. Solar
flux for Friday and Saturday should be around 130, and 125 for
Sunday and Monday. Flux values are expected to rise very gradually,
reaching 140 around June 8, 145 around June 11, and 150 around June
14. This is based on the recent solar rotation, and is blind to any
new activity that may emerge.

Last week's prediction that solar flux would peak over the weekend
was off. Instead it had peaked on the Thursday when the bulletin was
written. A geomagnetic disturbance that was forecast for Sunday was
only brief, but came up again on Monday when the planetary K index
was 4 during several periods. WA8OLD reported from Upper Michigan
that Sunday had the best 15 meter propagation he had seen in a long
time. He worked the world with low power and an inverted vee.

Also, KB9NXD wrote to remind us that
http://sec.noaa.gov/ftpdir/latest/wwv.txt gives the text of the WWV
solar indices broadcast. It you miss it on the air at 18 minutes
after the hour, you can also hear it repeated anytime at
303-497-3235. Every three hours the K index is revised, and this is
a good indication of geomagnetic stability and general conditions.
When the K index is below 3, HF propagation is often quite good.
When it is above 3, watch out. Since this is the end of May, now is
the time to review some monthly sunspot and solar flux averages.

Average daily sunspot numbers for January through May were 142.7,
131, 166.7, 163.6 and 135.1. Average daily solar flux values for the
same period were 166.6, 147.2, 177.7, 178.2 and 148.8. March and
April's averages were greatly affected by the huge rise in solar
activity around the transition from March to April.

Here are some path projections from WA8OLD in Sault Ste Marie,
Michigan. This should also be good for Ontario.

To Europe, 80 meters 0100-0400z, 40 meters 2330-0530z, 30 meters
2230-0630z, 20 meters open around the clock, best period 2300-0630z,
worst 1300-1630z, 17 meters 1000-1530z and 1830-0600z, 15 meters
possibly 1200-1930z.

To Brazil, 80 meters 0100-0900z, 40 meters 0000-1000z, 30 meters
2300-1030z, 20 meters 2030-1230z, 17 meters all hours, strongest
0000-0430z, weakest 0700-0830z and 1500-1800z, 15 meters possibly
0130-0300z and around 1500z.

To Australia, 80 meters 0830-1030z, 40 meters 0800-1130z, 30 meters
0730-1200z, 20 meters 0700-1330z, 17 meters 0600-0900z and
1030-1300z, 15 meters possibly 0500-0630z and 1130-0300z.

To Japan, 30 meters 1000-1130z, 20 meters 0700-1400z, 17 meters
0600-0900 and 1130-1530z, 15 meters possibly 1400-0400z.

Sunspot numbers for May 24 through 30 were 171, 146, 167, 189, 190,
131 and 105 with a mean of 157. 10.7 cm flux was 170.3, 161.9,
147.4, 146.9, 143, 138.5 and 132.3, with a mean of 148.6, and
estimated planetary A indices were 9, 8, 8, 9, 18, 10 and 5 with a
mean of 9.6.
NNNN
/EX