QST de W1AW
Propagation Forecast Bulletin 32 ARLP032
From Tad Cook, K7VVV
Seattle, WA August 7, 1998
To all radio amateurs
SB PROP ARL ARLP032
ARLP032 Propagation de K7VVV
Solar activity was up a bit for the month of July after being flat for several months. Average solar flux took a jump earlier in the year, from 93.4 for both January and February to 109.1 for March, 108.3 for April, 106.7 for May and 108.5 for June. Average solar flux for July was 114.1. A year ago the average solar flux for July, 1997 was 71.4.
Toward the end of each of the past few weeks there has been a great geomagnetic disturbance on Thursday or Friday, and this week is no exception. July 16 saw a planetary A index of 37, it was also 37 on July 23, it was 33 on July 31. On August 6 it was all the way up to 69, indicating a severe storm. The cause of this latest upset was probably a well placed coronal hole or mass ejection, and the excitement should continue for a few days, along with very high solar flux. Flux values on Thursday were 138.3, and solar flux is expected to climb over the next few days, Friday through Sunday, to 145, 150 and 150. The last time the solar flux reached 150 was over five years ago on March 11, 1993.
The planetary A index for the same three days is predicted to be 30, 18 and 10, so HF conditions could be really good by the end of the weekend. Don't forget that when conditions are bad on HF due to geomagnetic storming, auroral skip could be causing great excitement on VHF.
NASA released some encouraging news about the SOHO spacecraft this week after finally establishing radio contact on Monday. Although it is doubtful whether SOHO will ever again be a rich source of solar data, the NASA Deep Space Network has been able to consistently track the craft over the past few days as it sends 10 second carrier bursts in response to NASA commands.
Sunspot Numbers for July 30 through August 5 were 69, 107, 74, 121, 112, 80 and 85 with a mean of 92.6. 10.7 cm flux was 114.8, 113.7, 112.1, 109.6, 108.5, 115.8 and 126.8, with a mean of 114.5, and estimated planetary A indices were 12, 33, 15, 8, 6, 9, and 9, with a mean of 13.1.
Here are some path projections for the European CW DX Contest this weekend, using some optimistic numbers for Sunday.