QST de W1AW
Propagation Forecast Bulletin 50 ARLP050
From Tad Cook, K7VVV
Seattle, WA December 11, 1998
To all radio amateurs
SB PROP ARL ARLP050
ARLP050 Propagation de K7VVV
Solar activity was lower this week, with both average solar flux and sunspot numbers down about 10 points each when compared to the previous week. Average solar flux for the previous ninety days was 131, and solar flux was above this value on every day, indicating a good general upward trend.
Solar flux peaked at 162 on Tuesday, and the trend now is downward. For the ARRL Ten Meter Contest this weekend look for a solar flux of 132, 128 and 122 on Friday through Sunday. Geomagnetic indices should be unsettled to active, with the planetary A index peaking around 15 on Saturday.
It would be nice to have a higher solar flux for the ARRL Ten Meter Contest, but contesters can look forward to much better conditions than last year. Last year the Friday through Sunday solar flux for the 1997 ARRL Ten Meter Contest was 92.5, 89.3 and 90. This just wasn't enough for good propagation over most paths. Just plug the numbers into any popular propagation prediction program, and the predicted numbers for this weekend look great in comparison.
The general trend in solar activity has been up this year. Take a look at the chart at http://www.dxlc.com/solar/ or at http://www.wm7d.net/hamradio/solar/ and see the general upward trend. Beyond this weekend look for solar flux to drop to 120 or lower by December 16, then rise above 130 three days later and above 140 by December 22. Flux values are expected to peak above 150 around December 27.
NASA released an interesting story this week about solar wind squeezing ions out of the ionosphere. See the press release and images at http://www-spof.gsfc.nasa.gov/istp/news/9812/.
Sunspot Numbers for December 3 through 9 were 136, 109, 91, 106, 143, 158 and 132 with a mean of 125. 10.7 cm flux was 153.1, 148.2, 142.4, 142.3, 153.2, 162 and 153.9, with a mean of 150.7, and estimated planetary A indices were 7, 7, 12, 7, 6, 5 and 5, with a mean of 7.
Here are some path projections for the ARRL Ten Meter Contest this weekend.
Look for Europe from the East Coast around 1530-1700z, South America with strong signals around 1430-1930z, South Pacific around 1800-2200z, Hawaii around 1800-2030z, and the West Coast from 1800-1930z.
From the Central USA, look for Europe around 1600z, South America from 1500-2100z, South Pacific at 1730-2330z, Hawaii from 1800- 2300z, Japan around 2200-2300z, the East Coast around 1800-2000z and the West Coast from 1700-2100z.
From the West Coast, check South America around 1530-2330z, South Pacific around 1830-0030z, Hawaii around 2000-2100z, and Japan around 2230-0000z.