QST de W1AW
Propagation Forecast Bulletin 9 ARLP009
From Tad Cook, K7VVV
Seattle, WA February 26, 1999
To all radio amateurs
SB PROP ARL ARLP009
ARLP009 Propagation de K7VVV
Solar activity was down this week, but so were geomagnetic disturbances after a rough start. Last Thursday the Planetary A index was 54, the Boulder A index was 41, and the high latitude A index was 89. Friday wasn't much better, but on Saturday and Sunday geomagnetic activity was very low, with K indices at all latitudes at zero during many periods.
Average solar flux was down about 45 points from last week to this week, and average sunspot numbers were off about 65 points. Solar flux should continue to decline, with predicted flux values for this weekend, Friday through Sunday, at 120, 118 and 115, and planetary A indices at 8, 8 and 10. Solar flux is expected to bottom out around 105 from March 3-5, then rise to 130 by March 8, 160 by March 10, and peak around 200 on March 13. After that it is expected to decline to 120 around March 22. This is all based on the previous solar rotation, so new activity could increase these numbers with little warning. During that period geomagnetic conditions are expected to be unsettled around March 5 and 6, more so on March 11, and especially on March 16-18, about 28 days or one solar rotation since the last big disturbance.
The author received a nice email from JA7SSB passing along greetings from his JA colleagues. He says he likes the WA4TTK solar plotting program, and mentioned a ham radio web site he maintains at http://www.roy.hi-ho.ne.ip/hamradio/.
OK1HH, a Czech propagation forecaster, also sent along some propagation info and mentioned a site with his forecasts at http://sunkl.asu.cas.cz/~sunwatch/forecasts.html.
Sunspot Numbers for February 18 through 24 were 135, 122, 118, 103, 108, 38 and 56 with a mean of 97.1. 10.7 cm flux was 168.1, 164.2, 157.1, 147.2, 129.7, 127 and 119.8, with a mean of 144.7, and estimated planetary A indices were 54, 38, 5, 5, 4, 7 and 11, with a mean of 17.7.
Here are some path projections for this weekend from the center of the continental United States.