ARRL

ARRL Propagation Bulletin ARLP050 (1997)

SB PROP @ ARL $ARLP050
ARLP050 Propagation de K7VVV

ZCZC AP50
QST de W1AW
Propagation Forecast Bulletin 50  ARLP050
From Tad Cook, K7VVV
Seattle, WA  December 12, 1997
To all radio amateurs

SB PROP ARL ARLP050
ARLP050 Propagation de K7VVV

Average solar flux was down and average sunspot numbers were up this
week over the previous week.  Solar flux on every day was above the
ninety day average of 94, indicating a continuing upward trend.

Look for good conditions during the ARRL 10 Meter Contest this
weekend, although solar flux will not be as high as it has been
lately.  The predicted solar flux for Saturday and Sunday is 94 and
96, and stable geomagnetic conditions are forecast.  Following the
weekend the solar flux is expected to go above 100 for the rest of
the month.

Wire service stories this week reported from the American
Geophysical Society meeting in San Francisco that the two year old
Solar and Heliospheric Observatory (SOHO) is allowing better
understanding and prediction of coronal mass ejections and
interplanetary magnetic and particle storms.  Observations from SOHO
show that a particular buildup of magnetic fields on the Sun occurs
before a mass eruption.  You can visit the SOHO webpage at
http://sohowww.nascom.nasa.gov.

Sunspot Numbers for December 4 through 10 were 34, 58, 44, 70, 97,
94 and 72 with a mean of 67.  10.7 cm flux was 107.3, 103.8, 108.8,
99, 98.1, 96.7 and 95.1, with a mean of 101.3, and estimated
planetary A indices were 4, 8, 5, 3, 2, 2, and 15, with a mean of
5.6.

Here are some path predictions for 28 MHz for the 10 meter contest
this weekend:

From the Eastern USA to Europe check 1530-1630z, to South Africa
check 1330-1930z, especially 1500-1630z, to the Caribbean 1400-
2030z, especially 1530-1830z, to South America 1400-2030z,
especially 1530-1830z, to South Pacific 1700-2130z, especially
1800-1930z, to Hawaii 1800-2100z, especially 1830-1930z.

From Central USA to Europe check 1530-1630z, to South Africa check
1330-1930z, particularly 1430-1700z, to the Caribbean check 1400-
2030z, especially 1530-1830z, to South America 1400-2030z,
especially 1530-1830z, to South Pacific check 1700-2130z, especially
1800-1930z, to Hawaii check 1800-2100z, especially 1830- 1930z.

From Western USA to South Africa check 1730-2200z, especially around
1830z, to South America 1630-2330z, especially 1800-2130z, to the
Caribbean 1600-2200z, especially 1700-1900z, to South Pacific
1730-0130z, especially 1900-2130z, to East Asia 2200-0030z,
especially around 2300z and to Hawaii 1830-2330z.
NNNN
/EX