QST de W1AW
Propagation Forecast Bulletin 54 ARLP054
From Tad Cook, K7VVV
Seattle, WA December 21, 2001
To all radio amateurs
SB PROP ARL ARLP054
ARLP054 Propagation de K7VVV
Today is the "shortest" day of the year! The days are very short in northern latitudes. Here in Seattle, the hours between sunrise and sunset are more than seven and one-half hours longer on June 21 than they are now. Check out the nighttime bands such as 160 and 80 meters.
There weren't any big upsets from solar flares to disturb last weekend's ARRL 10-Meter Contest. Unsettled conditions did appear, but not until Monday, and even then the planetary A index only went to 15.
Solar flux and sunspot numbers were slightly lower this past week compared to the previous period. Average sunspot numbers were off by a little more than four points, and average solar flux was down by nearly eleven.
The view of the sun currently shows a few spots, with not much activity. The current outlook shows solar flux rising slowly in the near term, reaching a peak in the period December 30 through January 2. Solar flux is predicted to be right around 215 for Friday through Monday, and then rising slowly after that.
Even though there currently is not much activity, there is some growth in sunspot 9742. It is rotating toward a position where it is more Earth-directed, and it could threaten strong solar flares. There is also a group of sunspots on the sun's far side, detectable via helioseismic holography. There could be some more activity when these sunspots come into view.
Sunspot numbers for December 13 through 19 were 212, 202, 198, 204, 215, 210 and 158, with a mean of 199.9. The 10.7- cm flux was 220.2, 245.8, 217.8, 209.1, 205.5, 211.8 and 208.2, with a mean of 216.9. The estimated planetary A indices were 4, 4, 11, 10, 15, 8 and 9 with a mean of 8.7.