ARRL

ARRL Propagation Bulletin ARLP021 (2000)

SB PROP @ ARL $ARLP021
ARLP021 Propagation de K7VVV

ZCZC AP21
QST de W1AW  
Propagation Forecast Bulletin 21  ARLP021
From Tad Cook, K7VVV
Seattle, WA  May 26, 2000
To all radio amateurs 

SB PROP ARL ARLP021
ARLP021 Propagation de K7VVV

Sunspots and solar flux numbers have dropped since their peak last
week, although because the peak came at the end of the previous
reporting period on Wednesday, May 17, the average solar flux number
for this week is not much lower. Average solar flux is down less
than 2 points this week, and average sunspot numbers are down about
37 points.

There was a big geomagnetic shock on Wednesday, when the planetary A
index rose to 73, indicating severe storm levels. The planetary K
index was either 6 or 7 for 15 hours. This was after a quiet week
where the K index was often 1 or 2. Aurora was sighted as far south
as Oklahoma and Missouri on May 23 and 24.

The K index is updated every 3 hours, and a 1 point change is very
significant. The A index is updated every 24 hours, and represents
the average K index for the previous day. A 1 point change in the A
index is very small. For instance, if the K index were 2 for all of
the eight 3-hour periods in a day, the A index for the day would be
7. But if the K index were always 3 throughout a day, the A index
would be 15. A constant K index of 4 would result in an A index of
27, and a K index of 5 would mean an A index of 48. If the K index
were 6 for all periods in a day, then the A index would be 80, and
an A index of 132 would result if all periods had a K index of 7.

CW contesters concerned about the CQ Worldwide WPX test this weekend
can relax. The latest projection shows geomagnetic conditions
settling down. The predicted planetary A index for Friday through
Tuesday is 10, 10, 12, 20 and 15. There is more upset seen for early
next week, but Friday through Sunday does not look bad. The
predicted solar flux for Friday through Tuesday is 165, 160, 150,
145 and 140.Near term solar flux should bottom out near 130 around
June 2 or 3, then rise to a peak around the middle of June.

With longer days in the northern hemisphere along with higher
sunspot counts and solar flux, look for greater worldwide
propagation after dark on 20, 17 and 15 meters.

Sunspot numbers for May 18 through 24 were 297, 239, 282, 271, 207,
150 and 185 with a mean of 233. 10.7 cm flux was 252.9, 254.3,
245.6, 232.3, 214.9, 204.3 and 189.4, with a mean of 227.7, and
estimated planetary A indices were 10, 9, 6, 7, 9, 22 and 73, with a
mean of 19.4.

Here are some path projections for this weekend's contest, with the
best bets for working major points on the globe from the USA.

From the East Coast of the USA to Europe, 80 meters 0030-0500z, 40
meters 2330-0600z, 20 meters 2100-0830z, 15 meters possibly anytime
day or night, but not a good bet. To Southern Africa, 80 meters
0000-0430z, 40 meters 2330-0500z, 20 meters 2200-0230z and
0430-0600z, 15 meters 2130-0100z. To South America, 80 meters
0000-0930z, 40 meters 2330-1000z, 20 meters 2130-1100z, 15 meters
1900-0700z and 1000-1400z, 10 meters 1430-2300z and 0100-0400z.  To
Australia, 80 meters 0830-1000z, 40 meters 0800-1030z, 20 meters
0700-1200z, 15 meters 0600-0700z and around 1030z. To Japan, 20
meters 0900-1100z, 15 meters 1330-1730z and 0300-0500z. To the USA
West Coast, 80 meters 0230-1030z, 40 meters 0100-1200z, 20 meters
all hours, best 0330-0600z.

From the middle of the continental USA to Europe, 80 meters 0200-
0400z, 40 meters 0100-0600z, 20 meters 2230-0830z, 15 meters
1300-0230z. To South Africa, 80 meters 0130-0430z, 40 meters
0100-0430z, 20 meters 0000-0230z and 0400-0530z, 15 meters
2130-0130z. To South America, 80 meters 0130-1000z, 40 meters
0100-1030z, 20 meters 2300-1130z, 15 meters 2200-0700z and
1030-1230z, 10 meters possibly 2300-0600z. To Australia, 80 meters
0830-1130z, 40 meters 0800-1230z, 20 meters 0700-1300z, 15 meters
0700-0900z. To Japan, 80 meters around 1030z, 40 meters 0930-1130z,
20 meters 0800-1330z, 15 meters 0400-0700z and 1300-1330z.

From the USA West Coast to Europe, 40 meters 0330-0430z, 20 meters
0100-0800z. To Southern Africa, 80 meters 0330-0430z, 40 meters
0300-0430z, 20 meters 0100-0230z and 0330-0500z.  To South America,
80 meters 0300-1000z, 40 meters 0200-1100z, 20 meters 0100-1200z, 15
meters open all hours, best 0330-0800z, 10 meters 1700-0130z and
0330-0600z. To Australia, 80 meters 0900-1330z, 40 meters
0800-1400z, 20 meters 0700-1500z, 15 meters 0530-1000z, 10 meters
0530-0700z. To Japan, 80 meters 0930-1300z, 40 meters 0930-1330z, 20
meters 0700-1600z, 15 meters 0430-0830z and 1430-1500z and
1800-1900z. To the USA East Coast, 80 meters 0230-1030z, 40 meters
0100-1200z. 20 meters all hours, best 0330-0600z.
NNNN
/EX