ARLP010 Propagation de K7RA:
March 5, 2004

Propagation Forecast Bulletin 10 ARLP010
From Tad Cook, K7RA
Seattle, WA March 5, 2004
To all radio amateurs

ARLP010 Propagation de K7RA

The ARRL International DX Phone Contest is this weekend, March 6-7, and propagation should be good. Geomagnetic conditions are expected to be quiet, with the predicted planetary A index at 10 for Friday, March 5, and just 8 for the following three days. Solar flux is expected to rise to 105 for Friday and 110 for the following three days. Solar flux is currently expected to stay above 100 until March 17.

Average daily sunspot numbers for the past week were up nearly 15 points to 76.9, compared to the earlier week, and average daily solar flux increased over 5 points. Geomagnetic indices were about double this week over last. A solar wind stream caused this, but no geomagnetic storm erupted. Around March 10 and 11, earth should enter another solar wind, and this could cause a geomagnetic storm, possibly lasting until March 12.

The vernal equinox is only two weeks away. It will occur on Saturday, March 20, and will be the beginning of spring. For the next few weeks HF radio conditions should seasonally improve.

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

Sunspot numbers for February 26 through March 3 were 105, 90, 104, 81, 66, 50 and 42 with a mean of 76.9. 10.7 cm flux was 120.8, 122.2, 115.8, 110, 101.8, 98.8 and 90.4, with a mean of 108.5. Estimated planetary A indices were 5, 11, 20, 21, 18, 17 and 15, with a mean of 15.3.