ZCZC AP52
QST de W1AW
Propagation Forecast Bulletin 52 ARLP052
From Tad Cook, K7VVV
Seattle, WA December 23, 1999
To all radio amateurs
SB PROP ARL ARLP052
ARLP052 Propagation de K7VVV
HF radio conditions improved over the past week, with solar flux and sunspot numbers higher than the previous period, and geomagnetic indices more stable. Average planetary A index declined from 9.7 to 3.7, and average solar flux was up over 40 points. This is a happy combination, because often higher solar indices are coupled with less stable geomagnetic conditions. Look for solar flux to remain around 200 for Thursday and Friday of this week, and slip just below 200 on Christmas day. Planetary A indices are predicted at 7 for all three days.
Beyond this weekend look for solar flux to decline to around 150 by the end of the year, rising above 160 after the first week in January. Solar flux should top 200 again by the middle of next month. Look for unstable geomagnetic conditions returning around December 31 through January 2.
If you missed the Talk of the Nation program Science Friday on December 17 on National Public Radio, you will want to hear it over the web. Check the NPR archive at http://search.npr.org/cf/cmn/cmnpd01fm.cfm?PrgDate=12/17/1999PrgID=5 or after this week check the archives at http://search.npr.org/cf/cmn/cmnps01fm.cfm?prgid=5 and look for the December 17 program. The first hour featured Victor Pizzo and Howard Singer, two scientists from the NOAA Space Environment Center in Boulder, Colorado. They made many interesting comments about the current solar cycle and gave some great explanations concerning various space weather facts of interest to hams.
Merry Christmas from Seattle, where your bulletin author is performing in his seventeenth season as the grandfather in Pacific Northwest Ballet's production of The Nutcracker. Next week's bulletin ARLP053 will mark the end of the 9th year of writing these bulletins, after taking over from the late W1HDQ in early 1991. There should be a review of the solar numbers for this cycle in the first bulletin of the new year. You can always write with questions or comments to K7VVV@arrl.net.
Sunspot numbers for December 16 through 22 were 146, 179, 190, 154, 149, 129 and 130 with a mean of 153.9. 10.7 cm flux was 194, 200.7, 205.5, 206.9, 209.2, 217.2 and 201.7, with a mean of 205, and estimated planetary A indices were 5, 5, 5, 4, 3, 2 and 2, with a mean of 3.7.
Path projections this time around are for Christmas day from Charlotte, North Carolina.