ZCZC AP52
QST de W1AW
Propagation Forecast Bulletin 52 ARLP052
From Tad Cook, K7VVV
Seattle, WA December 13, 2002
To all radio amateurs
SB PROP ARL ARLP052
ARLP052 Propagation de K7VVV
W8GF pointed out in an email that last week's bulletin showed solar flux and sunspot number averages for the first eleven months of the year, but only ten values were displayed. I discovered that May 2002 values were missing from both lists. Looking back, ARLP046 also had this same problem with missing May numbers.
So here is the corrected list. Average sunspot numbers during January through November were 189, 194.5, 154.3, 144.4, 204.1, 146, 183.5, 191, 206.4, 153.9 and 159.8. The missing value last week was 204.1 for May 2002. Average solar flux was 227.3, 205, 179.2, 141.4, 178.4, 148.7, 174.4, 183.9, 175.8, 167 and 168.7. The missing flux value was 178.4 for May 2002.
This week conditions improved for HF, with slightly lower geomagnetic indices (the daily average planetary A index down from 13.6 to 9.7) and with solar flux and sunspot numbers up. Average daily sunspot numbers were up nearly 16 points, and average solar flux was up by nearly 8.
Conditions look good for the ARRL 10-Meter Contest this weekend with moderate geomagnetic conditions and a rising solar flux. Predicted solar flux values for Friday through Monday are 155, 160, 165 and 170.
Right now the days are very short, and they will keep getting shorter for the next week. Long nights are good for 40-meter propagation, but the higher frequencies close early. The winter solstice will come to North America on December 21, and after that we can watch the slow progression toward springtime propagation.
Sunspot numbers for December 5 through 11 were 153, 112, 106, 150, 189, 142, and 171, with a mean of 146.1. 10.7 cm flux was 148.7, 148.2, 151.1, 154.4, 156.3, 161.4, and 152.3, with a mean of 153.2. Estimated planetary A indices were 9, 10, 16, 12, 8, 7, and 6, with a mean of 9.7.