ZCZC AP13
QST de W1AW
Propagation Forecast Bulletin 13 ARLP013
From Tad Cook, K7VVV
Seattle, WA March 27, 1998
To all radio amateurs
SB PROP ARL ARLP013
ARLP013 Propagation de K7VVV
Solar activity remained high last week. Average solar flux for the previous ninety days rose two points from 97 to 99. Solar flux was well above these values on each day, indicating a good trend upward.
Looking at a graph of both solar flux and sunspot numbers over the past two months, a general upward trend becomes apparent. HF radio users can hope that the March 15 solar flux of 133 establishes a new level of activity for the current cycle that will be sustained. A glance at the chart at http://www.dxlc.com/solar gives a graphic illustration of this.
March 21 saw a geomagnetic storm, with planetary A indices jumping to 33. This was caused by a solar flare, and within a couple of days conditions had quieted back down.
Conditions over the next few days should be fair for the CQ Worldwide WPX Phone Contest. The solar flux on Friday through Sunday is forecast to be 111, 111 and 110. Flux levels are expected to drop below 100 after April 1, then above 100 after April 5 and above 110 by April 7, peaking near 120 around April 10 and 11. Active to minor storm geomagnetic conditions are expected over April 6 and 7.
Over the next few weeks good propagation between northern and southern hemispheres associated with spring conditions should continue. During daylight look for the best worldwide conditions on 15, 17 and 20 meters, and 30 and 40 meters after dark.
Sunspot Numbers for March 19 through 25 were 80, 100, 95, 114, 72, 83 and 79 with a mean of 89. 10.7 cm flux was 124.8, 126.5, 125.8, 127.6, 122, 120.6 and 115, with a mean of 123.2, and estimated planetary A indices were 4, 7, 33, 11, 5, 7, and 16, with a mean of 11.9.