ZCZC AP46
QST de W1AW
Propagation Forecast Bulletin 46 ARLP046
From Tad Cook, K7VVV
Seattle, WA November 12, 1999
To all radio amateurs
SB PROP ARL ARLP046
ARLP046 Propagation de K7VVV
Both solar flux and sunspot numbers were up this week, with average sunspot numbers rising nearly 37 and average flux up by nearly 25. Activity took a big jump in the past few days, with a sunspot number of 343 on Wednesday and solar flux at 248.5. Unfortunately for HF operators, this was accompanied by rising geomagnetic activity, so conditions have not been ideal.
Perfect conditions for the high bands probably exist when the solar flux is very high, but the geomagnetic field is very stable. This would be when the K index is below 3, preferably 0 or 1, and the A index is in the single digits. It is a sad fact that the type of activity that produces a densely charged ionosphere often produces flares and coronal holes, which tend to increase absorption.
What is generally bad for HF is not the same for 6 meters. While HF experienced high absorption, 6 meter operators were working DX. A number of reports were received this week from Midwest hams who worked South America and the Caribbean on 6 meters.
There is a really bright future for HF though, coming up this weekend. As of Thursday evening, the predicted solar flux for Friday through Sunday is 242, 245 and 245, and the planetary A index forecast is for 18, 10 and 8. So while the solar flux should rise to high levels, the geomagnetic indices should drop. What could be better? Look for great conditions for the Japan International DX Contest this weekend.
Beyond the weekend look for a declining solar flux, but it should only bottom out around 160 for November 18-21, then rise to 170 around Thanksgiving, then drop to 145 at the end of the month. Disturbed geomagnetic days include November 19-20 and 24, and the few days following December 4.
NASA has a web site devoted to observation of the Leonids meteor shower, which is coming November 17-18. Check it out at http://science.nasa.gov/newhome/headlines/ast11nov99_1.htm. This year's shower is predicted to be the biggest in decades. Another web site to check is http://solar.uleth.ca/sunnow/, which gives a real time image of the sun from a solar telescope at California's Sacramento Peak.
Sunspot numbers for November 4 through 10 were 108, 153, 188, 185, 232, 288 and 343 with a mean of 213.9. 10.7 cm flux was 147.5, 160.5, 150, 173.9, 191.9, 229.9 and 248.5, with a mean of 186, and estimated planetary A indices were 5, 4, 7, 24, 33, 25 and 12, with a mean of 15.7.
Path projections this weekend are for the Japan International Phone DX Contest. All of these paths are from United States locations to Japan.