ARRL

ARRL Propagation Bulletin ARLP049 (2000)

SB PROP @ ARL $ARLP049
ARLP049 Propagation de K7VVV

ZCZC AP49
QST de W1AW  
Propagation Forecast Bulletin 49  ARLP049
From Tad Cook, K7VVV
Seattle, WA  December 8, 2000
To all radio amateurs 

SB PROP ARL ARLP049
ARLP049 Propagation de K7VVV

Average solar flux was down and sunspot numbers were up this week.
At least there weren't any major geomagnetic disturbances. Quiet and
stable conditions prevailed, with A indices in the single digits.
Solar flux probably reached a short term minimum at 1800z on
December 6 of 140.2, and at the 1800z reading the next day it was
140.8. The official daily readings are at 2000z, which is why you
won't see those numbers reported here in the summary at the end of
this bulletin.

After the low flux numbers for the previous two days, solar flux is
expected to rise to a peak near 200 around December 20-23. Current
prediction shows flux values for Friday through Tuesday, December
8-12 at 145, 150, 150, 155 and 160. The next short term minimum for
solar flux is predicted for after the new year.

Unfortunately for hams looking forward to the 10-Meter contest this
weekend, the quiet conditions will probably not continue. The
predicted planetary A index for Friday through Tuesday is 15, 25,
15, 12 and 10. The active conditions in this weekend's forecast are
probably due to a coronal hole in the center of the visible solar
disk. This will be a problem for high latitude and east-west
propagation.  There was also a solar flare toward the end of the UTC
day on December 6.

Sunspot numbers for November 30 through December 6 were 191, 157,
141, 186, 120, 90 and 99 with a mean of 140.6. 10.7 cm flux was
192.3, 184.5, 167, 163.6, 152, 147 and 141, with a mean of 163.9,
and estimated planetary A indices were 6, 6, 4, 12, 10, 4 and 7 with
a mean of 7.
NNNN
/EX