ARLP050 Propagation de K7VVV:
December 12, 1997

Propagation Forecast Bulletin 50 ARLP050
From Tad Cook, K7VVV
Seattle, WA December 12, 1997
To all radio amateurs

ARLP050 Propagation de K7VVV

Average solar flux was down and average sunspot numbers were up this week over the previous week. Solar flux on every day was above the ninety day average of 94, indicating a continuing upward trend.

Look for good conditions during the ARRL 10 Meter Contest this weekend, although solar flux will not be as high as it has been lately. The predicted solar flux for Saturday and Sunday is 94 and 96, and stable geomagnetic conditions are forecast. Following the weekend the solar flux is expected to go above 100 for the rest of the month.

Wire service stories this week reported from the American Geophysical Society meeting in San Francisco that the two year old Solar and Heliospheric Observatory (SOHO) is allowing better understanding and prediction of coronal mass ejections and interplanetary magnetic and particle storms. Observations from SOHO show that a particular buildup of magnetic fields on the Sun occurs before a mass eruption. You can visit the SOHO webpage at

Sunspot Numbers for December 4 through 10 were 34, 58, 44, 70, 97, 94 and 72 with a mean of 67. 10.7 cm flux was 107.3, 103.8, 108.8, 99, 98.1, 96.7 and 95.1, with a mean of 101.3, and estimated planetary A indices were 4, 8, 5, 3, 2, 2, and 15, with a mean of 5.6.

Here are some path predictions for 28 MHz for the 10 meter contest this weekend: