QST de W1AW
Propagation Forecast Bulletin 35
From Tad Cook, K7VVV
Seattle, WA August 24, 2001
To all radio amateurs
SB PROP ARL ARLP035
ARLP035 Propagation de K7VVV
Thanks to K9LA for writing last week's bulletin. Carl is very knowledgeable about propagation, and quite generous to fill in while your regular writer takes a week off. Be sure to see his monthly propagation column in Worldradio Magazine.
Another generous contributor is WA4TTK, who wrote and continues to improve his free Solar Data Plotting Utility that graphs the data at the end of this bulletin. If you use this program, since there are two weeks of data at the end of this bulletin, you will need to separate the data into two files if you want the software to import the data automatically. Since it looks for key words in the bulletin to do its magic, just save two versions of the edited bulletin, one with each set of data. Or, you can use the new FTP feature to get the data from ARRL. If you aren't currently running this software, download it from http://www.craigcentral.com/sol.htm.
Average daily sunspot numbers dropped 21 points from the first week of the month to the second, then rose 13 points this week. Average daily solar flux has been nearly flat for the past few weeks, at 150.5, 156.3 and 154.1. Flux values are currently rising, and are expected at 175 for Friday and around 180 for Saturday through Wednesday. Geomagnetic conditions are expected to be unsettled to active, with planetary A indices of 12 on Saturday and Sunday and 20 on Monday and Tuesday.
Over the past couple of weeks the most active day was Friday, August 17, when the planetary A index was 29 and the K index rose to 6. Alaska's college A index was 60, and the college K index was 7 over nine hours.
Currently the earth is exiting a high-speed solar wind stream flowing from a coronal hole on the sun. A new large sunspot is rotating into view on the sun's southeast limb. There is also a large sunspot forming on the far side of the sun, seen in an image generated by helioseismic holography.
Here are some path projections to some of the DX locations in this week's ARRL DX Bulletin ARLD034. They are plotted from Richmond, Virginia.
Sunspot numbers for August 9 through 15 were 157, 119, 151, 196, 141, 133 and 155 with a mean of 150.3. 10.7 cm flux was 163.3, 160.3, 165, 159.8, 151.5, 147.3 and 146.7, with a mean of 156.3, and estimated planetary A indices were 10, 11, 6, 14, 19, 12 and 9 with a mean of 11.6.
Sunspot numbers for August 16 through 22 were 171, 158, 148, 142, 172, 169 and 183 with a mean of 163.3. 10.7 cm flux was 142.6, 144.9, 156.1, 157.5, 156.1, 160.2 and 161.5, with a mean of 154.1, and estimated planetary A indices were 8, 29, 14, 12, 10, 14 and 17 with a mean of 14.9.