ad7i (09/08/82)
qst de ad7i hr propagation forecast bulletin nr 36 from arrl headquarters newington ct september 7, 1982 to all radio amateurs bt the solar flux average for august was 169. after rising from a low of 136 on august 23, the flux rose for several days and then went into a zigzag course centered around 178. both the shape of the curve and the appearance of the sun thus far in september point to higher flux numbers in the next few days. a 15 point rise on september 4 closely parallels the curves for three preceding solar rotations. there is substantial activity coming around the east limb of the sun, with little due to be lost around the west limb in the next few days. thus we have a strong indication that the flux will peak above 200 during the forecast week. the bad news is that the high geomagnetic activity, and resultant generally poor propagation encountered at this point in two previous solar rotations will be back in force, until about september 10. this will not be continuous, so watch for brief periods of quite good conditions at unpredictable times this week. the trend in the k index given by wwv at 18 minutes after each hour is a good clue to impending changes in propagation. a value of 2 or lower, and a downward trend, point to improving propagation on all paths. rising values mean increased absorption on all but low latitude and transequatorial circuits. the best conditions of early fall can be expected about september 11 through 13. use the propagation charts in qst for august and september to determine the time of highest muf on any communications path. during periods of low k index the muf will be higher than the charts indicate, but the timing should be accurate. american sunspot numbers for august 26 through september 1 were between 101 and 150, for a mean of 130 ar