ZCZC AP17
QST de W1AW
Propagation Forecast Bulletin 17 ARLP017
From Tad Cook, KT7H
Seattle, WA April 25, 1997
To all radio amateurs
SB PROP ARL ARLP017
ARLP017 Propagation de KT7H
Solar activity was down last week, with the daily solar flux falling below the 74 average for the previous 90 days. The average flux for the week was 7 points below the previous week, and the average sunspot number was down by about 26. The really active geomagnetic day was April 17 when the A index was 26, and the quiet day was May 20 when the K index dropped to zero. Although many have called for the end of the previous solar cycle, we still seem to be stuck in the doldrums.
Solar flux should peak for the short term around or just above the mid seventies at the beginning of May, and then fall possibly below seventy in about three to four weeks from now.
Sunspot Numbers for April 17 through 23 were 29, 13, 12, 0, 0, 12 and 13 with a mean of 11.3. 10.7 cm flux was 71.7, 70.1, 69.9, 69.7, 70.1, 70.7 and 68.9, with a mean of 70.2, and estimated planetary A indices were 26, 16, 13, 4, 16, 18, and 9, with a mean of 14.6.
I would like to end this bulletin observing the recent death of Ed Tilton, W1HDQ. He wrote the propagation bulletin for many years. I took it over from him when he became ill during the peak of the last solar cycle.