ZCZC AP33
QST de W1AW
Propagation Forecast Bulletin 33 ARLP033
From Tad Cook, K7VVV
Seattle, WA August 15, 1997
To all radio amateurs
SB PROP ARL ARLP033
ARLP033 Propagation de K7VVV
For the second week in a row, solar activity was up. Every day this past week the solar flux was higher than the average for the previous 90 days, which at this point is 73. Perhaps the long quiet spell is over.
Solar flux was expected to peak in the upper-eighties this weekend, but the latest forecast shows that it probably already peaked at 82 on Wednesday, may drop to 80 on the day this bulletin is out, 78 on Saturday, and 76 on Sunday, August 17. Solar flux is expected to head back toward 80 around the end of the month, and up again toward 80 after the first week in September.
The ionosphere thins due to heating during the Summer, and this effect lessens as we move toward Fall in the northern hemisphere. The result should be better daytime MUF values. As daylight hours shorten, 40 meters should also get better at night. Currently 20 meters is still the best all around band for worldwide propagation.
Sunspot Numbers for August 7 through 13 were 55, 65, 61, 31, 53, 57 and 61 with a mean of 54.7. 10.7 cm flux was 77.9, 77.8, 78.1, 78.3, 79.5, 80.8 and 82, with a mean of 79.2, and estimated planetary A indices were 6, 5, 7, 7, 9, 5, and 12, with a mean of 7.3.