October 4, 1999

ZCZC AP40

QST de W1AW

Propagation Forecast Bulletin 40 ARLP040

From Tad Cook, K7VVV

Seattle, WA October 4, 1999

To all radio amateurs

SB PROP ARL ARLP040

ARLP040 Propagation de K7VVV

There was a delay in putting out the bulletin this week due to an unannounced change in servers at the Penticton Observatory. This delayed getting some of the data for this bulletin.

Last week, which we report as Thursday through Wednesday, we saw marginal HF conditions and a declining solar flux. The average sunspot number was down over 56 points and average solar flux was off by over 22 points compared to the previous week. The really active geomagnetic day was September 27, when the planetary A index was 37 and the highest planetary K index was 5. The higher latitudes had the worst conditions, with the College A index from Alaska at 66 for the day with the K index up to 7.

Solar flux probably bottomed out on Friday, October 1 at 121.6. It has been rising since then, and two days later on October 3 it was 141.3 for the morning reading at Penticton and 134.5 for the noon reading, which is the official number for the day.

The predicted solar flux for the next week, beginning Monday, October 4 is 138, 140, 142, 145, 148, 150 and 152. Unless new activity appears, solar flux will probably peak above 155 around the middle of the month. Predicted planetary A index for the same period is 15, 12, 12, 12, 10, 15 and 15. These predictions which go out a week are fairly rough beyond the first few days.

The beginning of October marks the end of the third quarter of the calendar year. Average solar flux for the month of September was 135.7, the lowest since April, when it was 117.2. Average monthly solar flux for May, June, July and August was 148.4, 169.8, 165.6 and 170.7. Average solar flux for the first quarter of 1999 was 136.7, actually one point higher than it was for the month of September and nine points higher than the average for last week. Flux for the second quarter was 145, and for the quarter just ended it was 157.6. This indicates a steady upward trend for cycle 23, although a peek at the graph at http://www.dxlc.com/solar/ looks like recent trends over the last few solar rotations are down. The predicted peak for this cycle is some time next year. You can see charts of the forecast data in Acrobat format by scrolling to the last few pages at http://www.sec.noaa.gov/weekly/pdf/prf1253.pdf. Also check the page which leads to this report, which can be found at http://www.sec.noaa.gov/weekly/index.html. This has the weekly NOAA SESC Preliminary Report and Forecast.

JA7SSB sent an interesting URL for a solar activity chart which is very beautifully done with lots of rich detail. You can see it at http://crlgin.crl.go.jp/sedoss/solact3/.

Sunspot numbers for September 23 through 29 were 78, 86, 38, 44, 49, 52 and 84 with a mean of 61.6. 10.7 cm flux was 136.9, 131.6, 125.4, 122.7, 123.8, 126 and 124.8, with a mean of 127.3, and estimated planetary A indices were 24, 6, 4, 15, 37, 20 and 19, with a mean of 17.9.

The path projection this time is for mid-week from **St. Louis,
Missouri**.

**To Europe**, 80 meters 2300-0800z, 40 meters 2100-0930z (peaking 0000-0600z), 30 meters 1930-1030z (peaking 2330-0630z), 20 meters 1130-0200z (peaking 2130-2330z), 17 meters 2130-2130z, 15 meters 1400-2030z, 12 meters 1530-1900z, 10 meters 1630-1900z.**To Southern Africa**, 80 meters 2300-0430z, 40 meters 2200-0500z, 30 meters 2130-0530z, 20 meters 2030-0500z, 17 meters 1900-0100z, 15 meters 1600-0000z, 12 meters 1330-2230z, 10 meters 1400-2200z, peaking around 2030z.**To the Caribbean**, 80 meters 2230-1130z (peaking 0200-0930z), 40 meters 2030-1330z (peaking 0000-1000z), 30 meters all hours, strongest 2330-1030z, weakest around 1630z, 20 meters all hours, strongest 0000-1000z, weakest 1530-1830z, 17 meters 1130-0200z, strongest late in the period, 15 meters 1200- 0100z, strongest late in the period, 12 meters 1230-0000z, 10 meters 1300-2300z.**To South America**, 80 meters 2330-1000z, 40 meters 2300-1000z, 30 meters 2230-1100z, 20 meters 2100-1200z, 17 meters 1200z-0200z (strongest 2330-0100z), 15 meters 1230-0100z (strongest late in the period), 12 meters 1300-2330z, 10 meters 1400-2300z.**To Australia**, 80 meters 0730-1300z, 40 meters 0700-1300z, 30 meters 0630-1330z, 20 meters 0530-1500z, 17 meters 0500-0800z and 1300-1500z, 15 meters 0130-0330z, 12 meters 1930-0230z, 10 meters 2030-0200z.**To Japan**, 80 meters 0800-1300z, 40 meters 0630-1300z, 30 meters 0530-1430z, 20 meters 1330-1800z and 0230 to 0400z, 17 meters 2000-0200z, 15 meters 2030-0200z, 12 meters 2100- 0030z, 10 meters 2130-2330z.**To Hawaii**, 80 meters 0330-1330z (peaking 0700-1130z), 40 meters 0230-1400z (peaking 0500-1200z), 30 meters 0130-1500z (peaking 0430-1200z), 20 meters all hours, peaking 0400 1200z, weakest 1430-1530z and 2000-2100z, 17 meters 1530- 0430z, strongest toward the end of the period, 15 meters 1600- 0300z, 12 meters 1700-0200z, 10 meters 1700-0130z.**To Alaska**, 80 meters 0100-1300z (strongest 0400-0500z), 40 meters 2330-1430z (best 0330-1130z), 30 meters all hours, best 0400-0700 z, weakest 1430-1530z and 1830-1930z, 20 meters 1500-0300z, strongest toward the end of the period, 17 meters 1800-0130z, 15 meters 2000-2330z, 12 meters possibly 2100-2300z.