QST de W1AW
Propagation Forecast Bulletin 11 ARLP011
From Tad Cook, K7VVV
Seattle, WA March 16, 2001
To all radio amateurs
SB PROP ARL ARLP011
ARLP011 Propagation de K7VVV
Solar flux declined this week, having reached a short-term peak a week prior to Wednesday. But average daily solar flux and sunspot numbers were higher this week than last. Daily sunspot numbers reached a peak of 174 on Monday. This is the highest it has been since February 9, when it was 179, or January 23, when it was 178.
Geomagnetic conditions have been quiet, with A indices in the single-digits. Quiet conditions should continue, although there is a possibility that sunspot group 9373, currently at the center of the solar disk oriented toward earth, could produce some solar flares on Thursday or Friday. You'll hear the results on the WWV reports a few days later if the K index rises above 3.
Solar flux is expected to be around 135 on Friday and 130 for the following few days, then rise to around 145 on March 22-24. By comparison, a year ago the average sunspot number and solar flux reported in this bulletin (ARLP011) was respectively 193.4 and 194.9.
Scott Craig has a revised version of his Solar Data Plotting Utility, which works with the data presented in this bulletin. The new version was released last week, and has a new feature which can connect to the internet and automatically download the solar data from an ARRL FTP site. His website is at http://www.craigcentral.com, and the software is at http://www.craigcentral.com/sol.htm.
Next week is the spring equinox, with anticipated spring propagation conditions. 15 and 20 meters should be open later into the evening, with 20 meters possibly open all night. 10 meters should improve around the change of seasons, but will probably degrade for worldwide propagation as spring moves toward summer.
Sunspot numbers for March 8 through 14 were 98, 113, 131, 139, 174, 110 and 159 with a mean of 132. 10.7 cm flux was 167.2, 161.4, 160.1, 157.8, 157.6, 147.3 and 142.2, with a mean of 156.2, and estimated planetary A indices were 6, 6, 5, 4, 10, 7 and 7 with a mean of 6.4.