ZCZC AP12
QST de W1AW
Propagation Forecast Bulletin 12 ARLP012
From Tad Cook, K7VVV
Seattle, WA March 24, 2000
To all radio amateurs
SB PROP ARL ARLP012
ARLP012 Propagation de K7VVV
Spring is here, and 10 and 12 meters are the place to be. A high solar flux and shifting seasons are again producing conditions where low power mobiles can work the world on the highest HF bands.
Last year at this time, the average solar flux for the week was 147.5. This week it was 207.8, much higher, and almost 13 points higher than last week's average. A steady upward recent trend can be seen in the graph at http://www.dxlc.com/solar/.
Geomagnetic indices have been quite low, but this should change. Active conditions are predicted for the next few days due to recurring coronal holes and some recent flare activity. A large coronal hole that has been returning for several months has split into three groups, and one of them crosses the sun's equator and is well positioned for disturbing radio conditions here on earth.
Weekend conditions for the CQ Worldwide WPX Phone Contest could be stormy. The predicted planetary A index for the next five days, Friday through Tuesday, is 25, 30, 20, 10 and 10, so it looks like the best contest conditions may be on Sunday. On March 31 and April 1 conditions may be unsettled or active again, but should be quiet until April 18. Solar flux predicted for the next five days is 230, 240, 245, 245 and 235. Flux values are expected to bottom out around 185 on April 12 or 13, then peak near 250 around April 22 or 23.
The High-Energy Solar Spectrograph Imager mission was set back at least six months when the satellite was mistakenly vibrated too hard in a test on a shake table at the Jet Propulsion Lab. The deployment of the satellite, which is designed to observe solar flares in their most energetic wavelengths, was expected to coincide with the solar maximum this year. You can read about the accident at http://www.msnbc.com/news/386019.asp?0a=23232C5 and about the HESSI mission itself at the NASA web site http://hesperia.gsfc.nasa.gov/hessi/index.html and at a University of California site, http://hessi.ssl.berkeley.edu/.
Sunspot numbers for March 16 through 22 were 138, 152, 142, 208, 240, 191 and 212 with a mean of 183.3. 10.7 cm flux was 184.4, 192.4, 194.8, 208.2, 210.3, 230.5 and 233.8, with a mean of 207.8, and estimated planetary A indices were 4, 6, 7, 8, 8, 6 and 11, with a mean of 7.1.
The path projections for this contest weekend are from Charlotte, North Carolina.