ZCZC AP30
QST de W1AW
Propagation Forecast Bulletin 30 ARLP030
From Tad Cook, K7VVV
Seattle, WA July 20, 2001
To all radio amateurs
SB PROP ARL ARLP030
ARLP030 Propagation de K7VVV
Last week's Propagation Forecast Bulletin ARLP029 stated that the next peak in solar flux would probably be near 170 around July 20-22. This now appears a bit optimistic based upon current readings. Solar flux and sunspot numbers have been up this week, but flux values probably reached a peak on Monday when the noon reading was 149.8.
Current forecasts show flux values slowly drifting downward over the next week, with values around 140 from Friday through Monday, then between 135 and 140 until around the end of the month.
Over the past week the average daily solar flux was up nearly 17 points and average sunspot numbers increased by over 63 points, when compared with the previous week's report.
Due to a persistent solar wind, geomagnetic conditions became unsettled to active this week. The most active days were Monday and Tuesday, when the planetary A index was 17. Alaska's College A index was also 17 on Monday, but jumped to 31 on Tuesday, when K indices went as high as 5 over several periods.
A slowly erupting coronal mass ejection billowed away from the sun on Tuesday, but there is little chance that it will affect the earth's magnetosphere.
Sunspot numbers for July 12 through 18 were 119, 146, 161, 142, 179, 191 and 193 with a mean of 161.6. 10.7 cm flux was 133.9, 133.3, 140.8, 142.1, 149.8, 145.6 and 143, with a mean of 141.2, and estimated planetary A indices were 9, 9, 13, 11, 17, 17 and 11 with a mean of 12.4.