ARRL

ARRL Propagation Bulletin ARLP020 (1999)

SB PROP @ ARL $ARLP020
ARLP020 Propagation de K7VVV

ZCZC AP20
QST de W1AW  
Propagation Forecast Bulletin 20  ARLP020
From Tad Cook, K7VVV
Seattle, WA  May 14, 1999
To all radio amateurs 

SB PROP ARL ARLP020
ARLP020 Propagation de K7VVV

Solar flux and sunspot count took a big leap this week, with average
sunspot numbers up nearly 64 points over last week, and average
solar flux up over 35 points.  Although last week's bulletin
predicted solar flux drifting back below 130, this was based upon
activity from about four weeks earlier rotating into view.  There
was no way to know in advance of the new sunspots which appeared
this week.

The effect on HF propagation of solar flux near 180 on Sunday was
dramatic.  The author could hear renewed worldwide activity on 17
meters from his mobile rig, and could not help but wonder if cycle
23 was finally making its long awaited increase.

There was a coronal mass ejection on May 10, and the effects of this
are now about to be felt.  The predicted A index on Thursday is 20,
but it should settle down to 12 and then 10 on Friday and Saturday.
Solar flux on those days is predicted to be 150, 145 and 145.  Flux
values should bottom out around 125 on May 21 or 22, then rise again
above 140 by May 27, reaching 170 again around June 5-7.  Expect
active geomagnetic conditions to return around May 25-28 due to
recurring coronal holes.

Jim Secan (jim@nwra.com) of Northwest Research Associates
(http://www.nwra.com) wrote wondering if any radio amateurs had
noticed unusual HF propagation over the polar regions between 1200
and 2000z on May 11.  He and Dave Evans of NASA
(ddevans@mail.hq.nasa.gov) noticed that there was an unusual
difference between southern and northern hemispheres in the extent
of the auroral zone, which can be seen graphically at
http://www.nwra.com/nwra/spawx/tiros.html.  Although Dave noticed
enhanced precipitation of energy in the northern polar cap region
during this period, the high latitude K index was zero for most of
the day.

In VHF news, N9BJG in Illinois heard the ZD8VHF 6 meter beacon from
Ascension Island in the South Atlantic at 2020z on May 10, the first
time since starting on VHF in 1976.  Also on May 10 WB8XX in Ohio
worked a number of South American stations on 6 meters.

Sunspot Numbers for May 6 through 12 were 141, 162, 192, 192, 174,
191 and 141 with a mean of 170.4.  10.7 cm flux was 146.9, 163.4,
171.9, 178.3, 169.5, 159.4 and 153.1, with a mean of 163.2, and
estimated planetary A indices were 11, 9, 6, 6, 5, 5 and 9, with a
mean of 7.3.

The path projection for this week is from New York.

To Western Europe, 80 meters 2330-0530z, 40 meters 2200-0700z, 30
meters 2030-0900z, 20 meters open all hours, best time 0030-0330z,
worst period 0830-0900z and 1300-1630z, 17 meters 1030-0230z, 15
meters possibly 1130-2230z.

To Eastern Europe, 80 meters 0000-0300z, 40 meters 2300-0400z, 30
meters 2100-0630z, 20 meters open all hours, best 0030-0200z, worst
0730-1430z, 17 meters 1300-2330z.

To Southern Africa, 80 meters 0000-0430z, 40 meters 2300-0430z, 30
meters 2130-0600z, 20 meters 1930-0200z and 0430-0730z, 17 meters
1700-0130z and around 0500 and 0800z, 15 meters 1200-0030z.

To the Caribbean, 80 meters 2300-1000z, 40 meters 2030-1230z, 30
meters all hours, best 0100-0830z, worst 1530-1730z, 20 meters
2100-1200z, 17 meters 0900-0500z, 15 meters 1230-0330z.

To South America, 80 meters 2330-0930z, 40 meters 2300-1000z, 30
meters 2130-1100z, 20 meters all hours, best 0000-0900z, worst
1530-1700z, 17 meters 1000-0500z, 15 meters 1300-0300z, 12 meters
possibly 1100-0330z, 10 meters possibly 1200-0130z.

To Hawaii, 80 meters 0500-1030z, 40 meters 0400-1130z, 30 meters
0300-1230z, 20 meters 0000-1600z, 17 meters 1100-0600z, 15 meters
possibly 1400-0400z.

To the South Pacific, 80 meters 0500-1030z, 40 meters 0430-1130z, 30
meters 0330-1200z, 20 meters 0130-1400z, 17 meters 0000-0700z and
1000-1400z, 15 meters 1700-0500z.

To Australia, 80 meters 0700-1000z, 40 meters 0630-1030z, 30 meters
0530-1200z, 20 meters 0400-1330z, 17 meters 0200-0730z, 15 meters
2030-0530z.

To Japan, 30 meters 0900-1100z, 20 meters 0500-1530z, 17 meters
1800-0400z and 1300-1500z, 15 meters possibly 1830-2200z.

To South Central Asia, 30 meters 2300-0100z, 20 meters 1900-0400z,
17 meters 1000-0500z, 15 meters 1330-2130z.
NNNN
/EX