ZCZC AP40
QST de W1AW
Propagation Forecast Bulletin 40 ARLP040
From Tad Cook, K7VVV
Seattle, WA September 27, 2002
To all radio amateurs
SB PROP ARL ARLP040
ARLP040 Propagation de K7VVV
Over the seven days of September 19-25 conditions were quiet with no real geomagnetic activity except some unsettled conditions on the 19th. The sun has also been quiet. Average sunspot numbers were down slightly for the past week and average solar flux was down quite a lot. Solar flux over the past two weeks has declined from over 200 toward 150, and over the next few days it is expected to go below 140.
After October 3 sunspots and solar flux are expected to rise, based upon the previous solar rotation. Flux values are expected to reach 200 again in the second week of October. Currently holographic images show no substantial sunspots on the sun's far side.
We are now in the Fall season, a great time for HF DX. Openings are better and longer, particularly on the higher frequencies. Although solar activity is still fairly high, we have passed the peak of the sunspot cycle, and this Fall will probably be far better for HF propagation than next Fall.
12 and 10-meters are now open to parts of the world that were unheard a couple of months back. For most of North America 12 and 10 should be open in the middle of the day toward Europe, during all daylight hours toward South America, and to Asia and the Pacific late in the afternoon to early evening. 12-meters will generally open earlier and close later than 10-meters.
For the CQ/RJ Worldwide RTTY DX Contest this weekend expect good conditions with no radio blackouts or solar flares likely.
Sunspot numbers for September 19 through 25 were 206, 237, 217, 218, 209, 240 and 230, with a mean of 222.4. 10.7 cm flux was 165.3, 164.4, 158.6, 160, 153.8, 157.9, and 153.4, with a mean of 159.1. Estimated planetary A indices were 13, 6, 9, 9, 5, 6, and 6, with a mean of 7.7.