ZCZC AP37
QST de W1AW
Propagation Forecast Bulletin 37 ARLP037
From Tad Cook, K7VVV
Seattle, WA September 11, 1998
To all radio amateurs
SB PROP ARL ARLP037
ARLP037 Propagation de K7VVV
Solar activity still remains fairly high. The average solar flux for the past week declined a little over 8 points, but the daily value actually peaked again on Sunday at 164.6. The average solar flux for the previous 90 days went up another two points to 124, and the solar flux on every day last week was above this level, indicating a continued general upward trend. Geomagnetic conditions were stable, so HF operators enjoyed good propagation.
Solar flux is expected to decline on Friday through Sunday from 140 to 135 to 130. It should then bottom out below 130 early in the week, then rise above 145 after September 18, above 155 after September 23, and peak below 170 from September 25 until the end of the month. Look for unsettled geomagnetic conditions around September 18 and 19, caused by a solar wind stream from a coronal hole. These predictions are based on the previously observable regions now rotated off the visible surface of the sun, so a burst of new activity could raise these values.
VE2FLE sends along an interesting resource for current geomagnetic conditions. It is an ftp site, which can be accessed using a web browser, and the downloaded file can be read with the same. Check ftp://suntwo.geolab.NRCan.gc.ca/pub/forecast/forecast.gif to see current geomagnetic activity in the sub-auroral, auroral and polar zones. In addition to current and recent activity, it also provides forecasts.
Sunspot Numbers for September 3 through 9 were 117, 73, 101, 142, 138, 164 and 156 with a mean of 127.3. 10.7 cm flux was 162.7, 154.7, 154.3, 164.6, 151.2, 153.5 and 145.3, with a mean of 155.2, and estimated planetary A indices were 9, 7, 6, 6, 7, 11, and 8, with a mean of 7.7.
