QST de W1AW
Propagation Forecast Bulletin 14 ARLP014
From Tad Cook, K7RA
Seattle, WA April 2, 2004
To all radio amateurs
SB PROP ARL ARLP014
ARLP014 Propagation de K7RA
The third week of spring begins this weekend. HF conditions have been good, with moderate geomagnetic conditions prevailing. Average daily sunspot numbers for the past week, March 25-31 were up when compared to the previous week, over 31 points to 123.9. Average daily solar flux rose 11 points.
On March 29, the sun showed several spots pointed earthward, including one large spot, 582. The sunspot number on that day was 169, the highest since November 30, when it was 178. Geomagnetic conditions weren't bad on March 29, with the planetary A index at 12 and mid-latitude A index at 9.
Any doubts that the overall decline of this solar cycle is well underway are dashed when examining some recent short-term averages. The first quarter of 2004 just ended, and average solar flux and sunspot numbers for the period are down. From the third quarter of 2002 through the first quarter of 2004, the average daily sunspot numbers were 193.5, 152.7, 120.3, 107.3, 110.2, 99.2 and 72.9. Average daily solar flux values for the same seven quarters were 178.1, 164.2, 134.3, 124.2, 120.8, 137.4 and 111.1.
Scott Craig has a minor bug fix for his Solar Data Plotting Utility. He fixed the leap year problem, and the program contains a data file updated through March 3. Download version 3.13 at http://www.craigcentral.com/sol.asp.
Over the next five days solar flux values should stay between 110-115. The planetary A index for April 2-6 is predicted to be 8, 8, 20, 20 and 35. The predicted rise in geomagnetic activity is because of a possible solar wind for Sunday, April 4. Today, April 2, there is a slight chance of the earth's magnetic field being hit by a coronal mass ejection.
This weekend is the Montana QSO Party. Here are some times when 40, 20, 15 and 10 meters may be open to Montana from various locations. The Montana end of the path in these calculations is in the western part of the state, roughly centered on Helena.
For more information concerning 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 March 25 through 31 were 128, 100, 129, 125, 169, 121 and 95 with a mean of 123.9. 10.7 cm flux was 127, 123.8, 127.6, 129, 128.6, 126.7 and 121.2, with a mean of 126.3. Estimated planetary A indices were 8, 11, 14, 17, 12, 12 and 7, with a mean of 11.6.