April 23, 1999

ZCZC AP17

QST de W1AW

Propagation Forecast Bulletin 17 ARLP017

From Tad Cook, K7VVV

Seattle, WA April 23, 1999

To all radio amateurs

SB PROP ARL ARLP017

ARLP017 Propagation de K7VVV

This was another down week for sunspots and solar flux, although with the flares and associated geomagnetic activity, we can't say that solar activity was down. On Saturday the planetary A index reached 47 with the K index as high as 7, an indication of a severe geomagnetic storm. This was caused by a coronal mass ejection, another name for a solar flare. Conditions were again unsettled to minor storm a few days later when the planetary A index was 21.

K0XY wrote to complain about the solar flux, and with all of the recent mail expressing fear that this cycle has already peaked, I decided to check with a forecaster at the NOAH Space Environment Center in Colorado. They are still sticking with their forecast made last year, that the peak of cycle 23 is probably a year from now, or perhaps it will peak at the end of 2000. It is important to keep in mind that when looking at past solar cycles, we are often observing smoothed numbers, and in fact there are often periods before a cycle reaches a peak when there will be a lull in activity. There is also a possibility that this cycle could be like cycle 22, which had a broad double peak.

It should be noted that while radio amateurs often hope for high solar activity, most of the individuals and organizations contacting the Space Environment Center with concerns about solar activity do not. These are the folks who are working with satellites, power distribution systems and pipelines, and worry about the sun bombarding the earth with energy during high flare activity.

Look for a flat solar flux this week, with the numbers remaining around 105. The planetary A index for the weekend, Friday through Sunday, should be 7, 7 and 10. Don't expect the solar flux to increase until after the end of April, with 130 by May 2, 140 by May 4, but then drifting back to 120 by May 12. Of course, as always, these projections are only based upon activity seen during the last rotation of the sun, so new sunspots could appear and liven things up.

Sunspot Numbers for April 15 through 21 were 95, 87, 99, 98, 90, 79 and 79 with a mean of 89.6. 10.7 cm flux was 121.8, 122.9, 115.7, 112.8, 110, 104.8 and 103.4, with a mean of 113.1, and estimated planetary A indices were 4, 14, 47, 6, 13, 21 and 12, with a mean of 16.7.

The path projection for this week is from **Alaska**, somewhere
between Anchorage and Fairbanks:

**To the geographic center of the contiguous 48 states of the U.S.**, 80 meters 0330-1230z, 40 meters 0130-1400z, 30 meters 1530-0830z and 1230-1400z, 20 meters 1630-0600z, and possibly 17 meters 1900-0200z.**To Western Europe**, 40 meters 0330-0600z, 30 meters 0400-1030z and 1700-0100z, 20 meters 0600-0830z and 1500-0000z, 17 meters possibly 1830-2300z**To Eastern Europe**, 30 meters 0230-0700z and 1300-2300z, 20 meters 0330-0800z and 1530-2130z, 17 meters possibly around 0600z or 1830-2100z.**To Southern Africa**, 20 meters 0400-0530z and 1500-0100z, 17 meters 2200-0000z and around 0430z.**To the Caribbean**, 80 meters 0400-1000z, 40 meters 0230-1030z, 30 meters 0030-1100z, 20 meters 1730-0530z, 17 meters 1930-0100z, 15 meters possibly 2030-0100z,**To South America**, 80 meters 0400-1000z, 40 meters 0300-1030z, 30 meters 0130-1030z, 20 meters 2230-0800z, 17 meters 2000-0430z, 15 meters 2130-2300z.**To Hawaii**, 80 meters 0530-1500z, 40 meters 0400-1700z, 30 meters all hours, with worst periods 1300z and 2130-2300z, 20 meters 1600-1930z and 2300-0930z, 17 meters 2200-0430z, 15 meters possibly 2330-0200z.**To South Pacific**, 80 meters 0600-1500z, 40 meters 0530-1600z, 30 meters 0430- 1700z, 20 meters around 1530z and then 1700-2030z and 0200-1100z, 17 meters 1800-2130z and 0100-0900z, 15 meters 2200-0430z.**To Australia**, 80 meters 0800-1530z, 40 meters 0730-1630z, 30 meters 0630-1730z, 20 meters 0500-1130z and again around 1600z, 17 meters 2030-0830z, 15 meters 0000- 0430z.**To Japan**, 80 meters 0900-1630z, 40 meters 0730-1830z, 30 meters 0600-2100z, 20 meters 1800- 1130z, 17 meters 2230-0800z, 15 meters possibly 2230-0330z.**To Central Asia**, 80 meters around 1430z, 40 meters 1330-1700z, 30 meters 1200-2100z, 20 meters 1630-2000z, 2330-0500z, 0830-0900z and 1130-1200z, 17 meters 0000- 0530z, 15 meters possibly 0030-0200z.