Register Account

Login Help

ARRL Propagation Bulletin ARLP014 (2004)

ARLP014 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7RA
Seattle, WA  April 2, 2004
To all radio amateurs 

ARLP014 Propagation de K7RA

The third week of spring begins this weekend.  HF conditions have
been good, with moderate geomagnetic conditions prevailing.  Average
daily sunspot numbers for the past week, March 25-31 were up when
compared to the previous week, over 31 points to 123.9.  Average
daily solar flux rose 11 points.

On March 29, the sun showed several spots pointed earthward,
including one large spot, 582.  The sunspot number on that day was
169, the highest since November 30, when it was 178.  Geomagnetic
conditions weren't bad on March 29, with the planetary A index at 12
and mid-latitude A index at 9.

Any doubts that the overall decline of this solar cycle is well
underway are dashed when examining some recent short-term averages.
The first quarter of 2004 just ended, and average solar flux and
sunspot numbers for the period are down.  From the third quarter of
2002 through the first quarter of 2004, the average daily sunspot
numbers were 193.5, 152.7, 120.3, 107.3, 110.2, 99.2 and 72.9.
Average daily solar flux values for the same seven quarters were
178.1, 164.2, 134.3, 124.2, 120.8, 137.4 and 111.1.

Scott Craig has a minor bug fix for his Solar Data Plotting Utility.
He fixed the leap year problem, and the program contains a data file
updated through March 3.  Download version 3.13 at

Over the next five days solar flux values should stay between
110-115.  The planetary A index for April 2-6 is predicted to be 8,
8, 20, 20 and 35.  The predicted rise in geomagnetic activity is
because of a possible solar wind for Sunday, April 4.  Today, April
2, there is a slight chance of the earth's magnetic field being hit
by a coronal mass ejection.

This weekend is the Montana QSO Party.  Here are some times when 40,
20, 15 and 10 meters may be open to Montana from various locations.
The Montana end of the path in these calculations is in the western
part of the state, roughly centered on Helena.

From Japan, 40 meters 0900-1400z, 20 meters 0600-0800 and
1400-1700z, 15 meters 2030-0430z and 10 meters possibly around

From Australia, 40 meters 0900-1430z, 20 meters 0800-1500z, 15
meters 1530-1730 and 0500-0730z and 10 meters 2130-0300z.

From New Zealand, 40 meters 0600-1400z, 20 meters 0430-1530z, 15
meters 0300-0700z and 10 meters 2000-0230z.

From Hawaii, 40 meters 0330-1500z, 20 meters open 24 hours, with
weakest signals 1000-1300 and 1900-2330z and strongest signals
0500-0800 and 1500-1830z.  Check 15 meters 1630-0530z and 10 meters

From Dallas, Texas, 40 meters open 24 hours with best signals
0200-1200z and weakest signals 1700-2100z.  20 meters should open
1230-0600z, with signals stronger later in the period.  15 meters
should open 1530-0130z, with best bet around 1800-2230z.  10 meters
might possibly open 1700-2200z.

From Atlanta, Georgia, 40 meters 2230-1430z, with strongest signals
0200-1130z.  Check 20 meters 1130-0630z, with signals stronger later
in the period.  15 meters 1400-0400z, 10 meters 1700-2230z, with
best chance around 2000-2100z.

From Montreal, Quebec, 40 meters 2300-1330z, strongest 0200-1030z.
20 meters 1200-0600z, stronger later in the period.  15 meters
1530-0200z, best bet around 1830-0000z.  10 meters might possibly
open 1500-0100z.

From Germany, 40 meters 0100-0630z, strongest 0200-0530z.  Check 20
meters 2100-0000z and 1830-2100z.  15 meters 1830-2100z, possible 10
meter opening 1700-2100z.

From Brazil, 40 meters 0130-1000z, 20 meters 2330-0800z and again
around 1130z, 15 meters 1300-0430z, weakest 1500-2000z.  10 meters
looks good 1630-2300z.

From Cuba, 40 meters 0100-1200z, 20 meters 1300-0530z (weakest
1600-2030z), 15 meters 1700-0000z and possible 10 meter opening

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the Propagation page on the
ARRL Web site at

Sunspot numbers for March 25 through 31 were 128, 100, 129, 125,
169, 121 and 95 with a mean of 123.9.  10.7 cm flux was 127, 123.8,
127.6, 129, 128.6, 126.7 and 121.2, with a mean of 126.3.  Estimated
planetary A indices were 8, 11, 14, 17, 12, 12 and 7, with a mean of


Instragram     Facebook     Twitter     YouTube     LinkedIn