ZCZC AP49
QST de W1AW
Propagation Forecast Bulletin 49 ARLP049
From Tad Cook, K7RA
Seattle, WA December 1, 2003
To all radio amateurs
SB PROP ARL ARLP049
ARLP049 Propagation de K7RA
At the end of this bulletin are the numbers for last week, as promised in Propagation Forecast ARLP048, issued on November 26. This reporting period (through last Wednesday, November 26) had average daily sunspot numbers over twice the value for the previous week, and average daily solar flux nearly 60 points higher.
The big upset during the last reporting period was the planetary A index of 117 on November 20. This happened when the energy from a coronal mass ejection swept over earth while the interplanetary magnetic field pointed south, leaving the earth's magnetic field vulnerable. The coronal mass ejection causing all the havoc was from sunspot 484, and occurred on November 18 around 0800z.
The recent recurrence of large sunspots has subsided with sunspots 484, 486 and 488 rotating off the visible solar disk. The sunspot number remains relatively high due to a number of smaller sunspots scattered across the solar surface. Solar flux should decline over the next few days to 145, 130, 130, 125 and 120 for Friday through Monday, December 1-5. Solar flux and sunspot numbers may reach a minimum for the short term around December 8 before rising again to current levels after the middle of the month.
This last weekend's CQ Worldwide CW DX Contest experienced some nice conditions. Geomagnetic indices were very quiet, with the mid-latitude A index at 4 and 7, and K indices as low as 1, and even 0 on the two days prior. Geomagnetic conditions should remain moderate through this week, but could rise again around December 7-15.
Average daily solar flux and sunspot numbers for November were a bit lower than October, but October's numbers were higher than recent months. Average daily sunspot numbers for November 2002 through November 2003 were 159.8, 144.8, 150.0, 87.9, 119.7, 114.3, 89.6, 118.4, 132.8, 114.3, 82.6, 118.9 and 103. Average daily solar flux values for the same months were 168.7, 157.2, 144, 124.5, 133.5, 126.8, 116.6, 129.4, 127.7, 122.1, 112.2, 155.5, and 140.8.
For more information about propagation and an explanation of the numbers used in this bulletin see the Propagation page on the ARRL Web site at http://www.arrl.org/tis/info/propagation.html.
Sunspot numbers for November 20 through 26 were 118, 131, 123, 158, 149, 202 and 209 with a mean of 155.7. 10.7 cm flux was 175.2, 177, 176.2, 178.2, 177.3, 170.7 and 170.9, with a mean of 175.1. Estimated planetary A indices were 117, 39, 22, 21, 12, 13 and 9, with a mean of 33.3.