QST de W1AW
Propagation Forecast Bulletin 44 ARLP044
From Tad Cook, K7VVV
Seattle, WA October 30, 1998
To all radio amateurs
SB PROP ARL ARLP044
ARLP044 Propagation de K7VVV
Solar activity was sharply lower last week. Average sunspot numbers dropped by well over half and average solar flux declined over 17 points to around 109. This seems to be cyclical though, since the average solar flux was down to the same level four weeks ago, roughly corresponding to the rotation of the sun. Average solar flux for the previous ninety days declined this week from 132 to 131, and the solar flux values were far below this value on every day of the past week.
Conditions were fair for the DX contest last weekend, and although solar activity was low, there was quite a bit of activity on 10 meters where the author of this bulletin operated mobile. An old IC730--unused since the previous solar cycle--was dusted off, placed in the car, and when hooked to a quarter wave trunk mounted whip. It was clear that 10 meters was back. Here on the west coast it was fascinating to observe the propagation following the sun, with many contacts to JA, VK and ZL around sunset.
KH6BZF sent a note on October 28 proposing that perhaps we have passed a temporary lull in solar activity, and to support this idea he noted several solar flux readings from the observatory in Penticton, British Columbia. These readings are taken three times per day, at 9:00 AM, Noon and 3:00 PM local time, although it is the noon measurement that is used for the official solar flux number for the day. The twelve consecutive solar flux readings for October 26 through 29 were 104.8, 104.1, 104.9, 101.7, 103, 103.8, 104.8, 107.8, 108.1, 109.7, 109.5 and 112.9. You can check the progression yourself on the web at Cary Oler's Solar Terrestrial Dispatch page at http://holly.cc.uleth.ca/solar/index, then click on "Solar Activity" in the left frame, then "10.7 cm Solar Radio Flux."
The predicted solar flux for this Friday through Sunday is 115, 115 and 120, and the projected planetary A index is 10, 8 and 8. This should mean slightly better conditions for the BARTG RTTY Contest this weekend compared to the CQ World Wide DX Phone Contest last weekend.
Look for unsettled geomagnetic conditions around November 3, and again from November 16-21, due to recurring coronal holes. Solar flux should remain above 120 through November 13, then retreat to 110 by November 20. This is all based on the previous solar rotation, so with luck perhaps some unseen new activity will rotate into view, improving HF propagation.
Radio Netherlands has a great collection of propagation web links. See them at http://www.rnw.nl/realradio/propagation.html.
Sunspot Numbers for October 22 through 28 were 60, 71, 43, 49, 50, 17 and 33 with a mean of 46.1. 10.7 cm flux was 114.9, 112.5, 110.9, 107.5, 104.1, 103 and 107.8, with a mean of 108.7, and estimated planetary A indices were 18, 13, 13, 16, 7, 6 and 12, with a mean of 12.1.