ARRL

ARRL Propagation Bulletin ARLP039 (1999)

SB PROP @ ARL $ARLP039
ARLP039 Propagation de K7VVV

ZCZC AP39
QST de W1AW  
Propagation Forecast Bulletin 39  ARLP039
From Tad Cook, K7VVV
Seattle, WA  September 24, 1999
To all radio amateurs 

SB PROP ARL ARLP039
ARLP039 Propagation de K7VVV

This week was a big disappointment for HF radio enthusiasts.  Last
week's Propagation Forecast Bulletin, ARLP038, stated that on
Thursday, September 23, the solar flux should be around 220.  This
was the date of the autumnal equinox, generally a peak time for HF
propagation.  Unfortunately the sunspots did not materialized and
the solar flux for the day was over 80 points lower than predicted.

Not only have solar flux and sunspot numbers been lower than
expected, but geomagnetic disturbances were prevalent as well.
Wednesday was the most active period, when the planetary A index was
37.

What's next?  Currently the flux is around 137 as this is being
written on Thursday, and the predicted values for Friday through
Sunday are 135, 135 and 130.  Predicted planetary A index is 15, 12
and 10.  Beyond the weekend the best guess is for solar flux to go
below 130 after September 27 and bottom out around 110 on October 5.
Flux values are not expected to rise above the current level until
October 11, and peak around 160 by mid-month.

Active geomagnetic conditions could reappear around October 4 and
again around October 9 and 10.

Despite the disappointing numbers, the author of this bulletin has
had fun this week on HF mobile.  Abandoning the usual 17 meter
operation, 10 and 15 meters were tried, and consistent contacts with
loud signals from Japan during the afternoon commute were made after
2300z above 21.3 MHz SSB.

Sunspot numbers for September 16 through 22 were 153, 144, 152, 113,
78, 82 and 103 with a mean of 117.9.  10.7 cm flux was 158.2, 157.5,
151.6, 149.3, 145, 146.8 and 140.4, with a mean of 149.8, and
estimated planetary A indices were 32, 15, 16, 10, 10, 10 and 37,
with a mean of 18.6.

Path projections for this week are from Birmingham, Alabama.

To Europe, 80 meters 2300-0730z (peaking 0200-0500z), 40 meters
2130-0900z (peaking 0000-0530z), 30 meters 2030-1000z (best
0000-0600z), 20 meters all hours, best 0000-0200z, weakest
0700-1130z), 17 meters 1230-2300z (strongest later in period), 15
meters 1300-2200z, 12 meters 1430-2100z, 10 meters 1630-1930z.

To Southern Africa, 80 meters 2300-0430z, 40 meters 2230-0430z, 30
meters 2200-0530z, 20 meters 2100-0630z (best 0000- 0300z), 17
meters 1930-0230z, 15 meters 1700-0130z, 12 meters 1200-0000z
(strongest toward end of period), 10 meters 1300-2230z.

To the Caribbean, 80 meters 2230-1100z, 40 meters 2000-1330z, 30
meters open all hours, best 0000-0930z, weakest 1600-1800z, 20
meters open all hours, best 0000-1000z, weakest 1530- 1830z, 17
meters 1130-0230z, 15 meters 1200-0130z, 12 meters 1230-0000z, 10
meters 1330-2230z.

To South America, 80 meters 2300-1000z, 40 meters 2300-1030z, 30
meters 2200-1100z, 20 meters 2030-1230z, 17 meters open all hours,
best 0030-0730z, 15 meters 1130-0600z, 12 meters 1200-0230z, 10
meters 1300-0100z.

To Australia, 80 meters 0730-1200z, 40 meters 0700-1300z, 30 meters
0600-1330z, 20 meters 0500-1430z, 17 meters 0330-0700z and around
1300z, 15 meters 0300-0430z, 12 meters 0130- 0230z, 10 meters
0030-0130z.

To Japan, 80 meters 0830-1200z, 40 meters 0800-1230z, 30 meters
0700-1330z, 20 meters 1230-1530z and 0530-0630z, 17 meters
2030-0300z, 15 meters 2030-0200z, 12 meters 2130-0030z, 10 meters
2200-2230z.

To Hawaii, 80 meters 0400-1300z, 40 meters 0230-1400z, 30 meters
0130-1430z, 20 meters 0030-1630z, 17 meters 1530-0700z and around
1300z, 15 meters 1600-0430z, 12 meters 1630- 0300z, 10 meters
1700-0200z.
NNNN
/EX