Register Account

Login Help

ARRL Propagation Bulletin ARLP014 (2000)

ARLP014 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7VVV
Seattle, WA  April 7, 2000
To all radio amateurs 

ARLP014 Propagation de K7VVV

The sunspot number took a big leap this week, rising to 301 on
Sunday. It has not been this high since November 12 of last year,
when it was 324. Two days prior on November 10 meters the solar flux
was 343, which is still the record for this cycle. The average
sunspot count for the week was only up about 8 points though, and
average solar flux was about the same as last week.

Solar flux is a measurement of 2.8 GHz energy from the sun, measured
at the Dominion Radio Astrophysical Observatory operated by the
National Research Council Canada in Penticton, British Columbia. You
can visit the observatory web site at

Sunspot numbers are calculated by multiplying the number of visible
sunspot groups by 10, and adding the number of individual spots in
all the groups. A multiplication factor is also used, and it differs
for each observatory. You can see a complete explanation for sunspot
numbers and their derivation at

Geomagnetic indices have been high this week, with the average
planetary A index almost double last week's number. The A index was
in double-digits every day, with April 4 being the most disturbed.
The planetary A index was 21, with planetary K indices as high as 5,
and the mid-latitude index at 6 during the same period.

Coming up on Saturday and Sunday is the HF CW weekend for the Japan
International DX Contest. Unfortunately, as this bulletin is being
written on Thursday night, a major geomagnetic storm is raging. An
interplanetary shock wave passed earth at 1730z on April 6, and
Aurora have been spotted in North America as far south as North
Carolina. The planetary K index for the end of thez day on Thursday
was 8, and the A index was 56. The Boulder K index at 0300z on
Friday is also 8. A severe geomagnetic storm began at 0100z on April

For the next five days, Friday through Tuesday, the expected
planetary A index is 30, 20, 15, 10 and 7. The predicted solar flux
for the same five days is 175, 180, 180, 175 and 170.  Solar flux is
expected to rise above 200 again around April 14 and stay there well
into the month of May.

Sunspot numbers for March 30 through April 5 were 225, 248, 287,
301, 252, 184 and 221 with a mean of 245.4. 10.7 cm flux was 205.5,
225.4, 222.9, 219.3, 215.4, 206.7 and 194.4, with a mean of 212.8,
and estimated planetary A indices were 10 meters, 19, 14, 16, 12, 21
and 12, with a mean of 14.9.

Path projections for this week are for the Japan International DX CW
Contest. Because the contest is for 10, 15 and 20 meters only, and
for international stations to work Japan, the path projections will
all be toward Japan and for 10, 15 and 20 meters only.

From Boston, Massachusetts, 20 meters 0930-1300z, 15 meters
2000-0000z, 10 meters possibly 2100-0100z.

From New York City, 20 meters 0900-1230z, 15 meters possibly
1100-1500z (best around 1400z), 10 meters possibly 2000-0100z.

From Atlanta, Georgia, 20 meters 1130-1330z, 15 meters 1930-0330z,
10 meters possibly 2030-0000z.

From Nashville, Tennessee, 20 meters 1130-1400z, 15 meters 1930-
0330z, 10 meters 2100-2330z.

From Louisiana, 20 meters 1130-1400z and 0630-0730z, 15 meters
2000-0500z, 10 meters 2100-0000z.

From Houston, Texas, 20 meters 0700-0830z and 1130-1430z, 15 meters
2000-0600z (stronger toward the end of the period) and again around
1330z, 10 meters 2100-0030z.

From the center of the contiguous 48 United States, 20 meters 1300-
1530z, 0600-0700z and again around 0800z, 15 meters 2000-0400z
(weaker toward the middle of the period), 10 meters possibly around

From Chicago, 20 meters 1100-1400z, 15 meters 2000-0100z.

From Salt Lake City, 20 meters 0630-0830z and 1330-1630z, 15 meters
2000-0500z, 10 meters possibly around 2300-0030z.

From Billings, Montana, 20 meters 1400-1630z and 0630-0830z, 15
meters 2000-0330z.

From Arizona, 20 meters 0700-1030z and 1230-1530z, 15 meters
1930-0730z, 10 meters 2130-0030z.

From Los Angeles, 20 meters 0630-1030z and 1300-1630z, 15 meters
2000-0730z, 10 meters 2130-0100z.

From San Francisco, 20 meters 0630-1000z and 1330-1700z, 15 meters
2000-0730z, 10 meters 2200-0000z.

From Portland, Oregon, 20 meters 0630-0900z and 1500-1730z, 15
meters 2030-0430z.

From Hawaii, 20 meters 0530-1930z, 15 meters 1930-1200z, 10 meters


Instragram     Facebook     Twitter     YouTube     LinkedIn