October 8, 1999

ZCZC AP41

QST de W1AW

Propagation Forecast Bulletin 41 ARLP041

From Tad Cook, K7VVV

Seattle, WA October 8, 1999

To all radio amateurs

SB PROP ARL ARLP041

ARLP041 Propagation de K7VVV

Solar flux and sunspot numbers were up this week, with sunspot numbers almost double the week previous, but average solar flux up less than six points. Recent geomagnetic instability finally quieted down, and on Wednesday morning UTC (Tuesday night in North America) the K index at both the mid latitudes and the College Index from Alaska were both zero.

Solar flux has been falling the past few days, after peaking at 146.2 on Tuesday. The official daily numbers are always from the 2000 UTC reading at Penticton, British Columbia, but there are readings at 1700 and 2300 UTC as well. Following the 2000 UTC reading on Tuesday, the flux for each of the three daily readings, through 2000 UTC Thursday were 146.7, 139.6, 133.6, 132.1, 131.7, and 129.4.

The projected flux values for the next seven days, Friday through Thursday, October 14 are 130, 135, 140, 145, 145, 150, and 150. The projected A indices for the same dates are 10, 15, 25, 30, 20, 15 and 15. Monday, October 11 looks like an unstable geomagnetic day. October 24 could be a bad day as well.

W7AFC wrote to ask for an explanation of the various numbers presented in this bulletin. The last time this bulletin had a detailed explanation of the meaning of the numbers was ARLP030. You can see it at http://www.arrl.org/w1aw/prop/1999-arlp030.html on the ARRL web site.

The path projections are intended to show the times when the bands are most likely to be open to the target areas from the point of origin, which changes every week. There may be openings at other times, but the periods shown are a very good bet for a strong opening.

Sunspot numbers for September 30 through October 6 were 84, 67, 47, 117, 148, 160 and 176 with a mean of 114.1. 10.7 cm flux was 124.8, 121.6, 126.3, 134.5, 144.4, 146.2 and 133.6, with a mean of 133.1, and estimated planetary A indices were 29, 11, 15, 10, 15, 16 and 6, with a mean of 14.6.

The path projection for this weekend is **from Billings, Montana**.

**To Europe**, 80 meters 2300-0830z (peaking 0300-0530z), 40 meters 2100-1100z (peaking 0100-0600z), 30 meters open all hours, best 0000-0630z, weakest 1400-1730z, 20 meters 1300-0030z (strongest late in the period), 17 meters 1400-2130z, 15 meters 1500-2030z, 12 meters 1700-1930z, 10 meters 1730-1900z.**To Southern Africa**, 80 meters 0000-0400z (peaking 0130-0200z), 40 meters 2330-0430z, 30 meters 2200-0500z, 20 meters 2030-0500z, 17 meters 1800-0100z, 15 meters 1730-2100z, 12 meters 1630-2100z, 10 meters 1800-2000z.**To the Caribbean**, 80 meters 2330-1100z, 40 meters 2230-1200z, 30 meters 2030-1400z, 20 meters 1230-0200z (stronger toward the end of the period), 17 meters 1400-0100z, 15 meters 1430-0000z, 12 meters 1600-2230z, 10 meters 1800-2100z.**To South America**, 80 meters 0030-1000z, 40 meters 0000-1030z, 30 meters 2300-1100z, 20 meters 2200-1100z, 17 meters 2000-0300z, 15 meters 1330-0200z, 12 meters 1400-0030z, 10 meters 1430-2330z.**To Australia**, 80 meters 0830-1430z, 40 meters 0800-1530z, 30 meters 0730-1530z, 20 meters 0700-1700z, 17 meters 1500-1630z, 15 meters 2030-2200z and 0330-0500z, 12 meters 2100-0300z, 10 meters 2130- 0200z.**To Japan**, 80 meters 0730-1430z, 40 meters 0700-1530z, 30 meters 0600-1700z, 20 meters 2030-2200z and 0200-0600z, 17 meters 2030- 0330z, 15 meters 2100-0230z, 12 meters 2130-0030z, 10 meters 2200- 2300z.**To Hawaii**, 80 meters 0300-1430z, 40 meters 0200-1530z, 30 meters 0100-1700z, 20 meters 1400-0730z, 17 meters 1630-0400z, 15 meters 1700-0300z, 12 meters 1730-0130z, 10 meters 1800-0000z.**To Alaska**, 80 meters 0030-1530z (best 0500-1230z), 40 meters and 30 meters very strong all hours, best 0330-1300z, weakest 1900-2130z, 20 meters 1500-1600z and 1800-0500z, 17 meters 1600-0330z, 15 meters 1700-0200z, 12 meters 1800-0030z, 10 meters 1930-2300z.