QST de W1AW
Propagation Forecast Bulletin 48 ARLP048
From Tad Cook, K7VVV
Seattle, WA November 22, 2002
To all radio amateurs
SB PROP ARL ARLP048
ARLP048 Propagation de K7VVV
No geomagnetic storm emerged for last weekend's ARRL Phone Sweepstakes. Conditions were very quiet, with the mid-latitude A index for Friday through Sunday a placid 8, 3 and 5, and the planetary A index at 11, 8 and 8. Mid-latitude K indices were 0 over several periods on Saturday and Sunday, which is fabulous for HF conditions.
Average daily sunspot numbers were down over 62 points this week over last, and average solar flux was down nearly 5 points.
Again at the end of this week earth is within a solar wind stream causing a rise in geomagnetic indices and likely to cause aurora. Sunspot 198, squarely aimed at earth on Thursday has a potential for solar flares.
On Thursday (November 21) the planetary K index rose to a very high value of 7, and the planetary A index was 50. The planetary A index has not been this high since October 1. Also on Thursday the high latitude College A index (measured in Alaska) was 62. For the CW weekend of the CQ Worldwide DX Contest the predicted planetary A index for Friday through Sunday is 35, 20 and 15. Solar flux is predicted to rise very gradually over the next few weeks to just below 200 before mid-December.
The winter solstice is a month away. As the hours of daylight recede, higher bands are closing earlier, but 20 meters should still stay open into the evening, often to points in the southern hemisphere. Nighttime MUF's (Maximum Usable Frequency) will be somewhat lower as the days get shorter, so 40 and 80 meters will become more desirable. For instance, using W6ELprop to check MUF between Seattle and Japan with a solar flux of 155, on November 21 the period with MUF below 10 MHz runs from 1330-1430z, but on December 21 it is from 1300-1530z.
Sunspot numbers for November 14 through 20 were 185, 185, 162, 139, 119, 105, and 108, with a mean of 143.3. 10.7 cm flux was 184.1, 197.5, 199.2, 184.7, 178.9, 168.2, and 159.1, with a mean of 181.7. Estimated planetary A indices were 9, 11, 8, 8, 12, 14, and 17, with a mean of 11.3.