ZCZC AP26
QST de W1AW
Propagation Forecast Bulletin 26 ARLP026
From Tad Cook, K7VVV
Seattle, WA June 30, 2000
To all radio amateurs
SB PROP ARL ARLP026
ARLP026 Propagation de K7VVV
Solar flux and sunspot numbers were down this week, with average solar flux off over 14 points and average sunspot numbers down by over 46 points compared to the previous week. Conditions over Field Day weekend were not bad, with Planetary A indices of 17 and 8 for Saturday and Sunday and middle-latitude A indices of 10 and 11 for the same days. The predicted planetary A indices from last week's bulletin ARLP025 were 15 and 20 for the weekend.
N5LYG and KK5CA wrote about six meter conditions from their Field Day site in Southeast Texas from grid EM20. They used a modest setup with a 3 element beam at 20 feet, and worked 343 stations on six meter SSB. The furthest stations worked were in New York and Pennsylvania to the east and Idaho to the northwest. They had many contacts in Indiana and Illinois, but found it odd that not one California station was heard. They only worked 130 stations on 40 meters using a delta loop at 50 feet, and their group felt that 40 meter conditions were terrible. From the author's location in Seattle, 40 sounded good for the domestic contacts that are the goal in Field Day, but 6 meters was not monitored here.
K9LA wrote recently with a comment about computer programs that predict shortwave propagation based upon solar indices. He reminds us that these programs are based on models that use monthly mean ionospheric parameters and smoothed sunspot numbers for the month, not daily solar flux values. He said that the daily state of the ionosphere does not track daily solar flux very well. He feels that it is best to use recent average sunspot numbers instead of the predicted solar flux for the next few days to predict conditions for the immediate future.
Speaking of the immediate future, the predicted solar flux for Friday through Tuesday is 165, 165, 170, 175 and 180, and planetary A index for those days is forecast to be 8, 8, 12, 10 and 8. Last week's bulletin ARLP025 stated that solar flux should begin rising around July 1, and this still looks to be the case. Current projections show solar flux peaking around 200 from July 10-13. Unsettled to active geomagnetic conditions are expected around July 11-12.
Sunspot numbers for June 22 through 28 were 187, 182, 190, 177, 180, 206 and 166 with a mean of 184. 10.7 cm flux was 179.7, 175.2, 168.3, 175.1, 177.4, 178.6 and 175.3, with a mean of 175.7, and estimated planetary A indices were 8, 23, 17, 8, 33, 18 and 14, with a mean of 17.3