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ARRL Propagation Bulletin ARLP046 (2000)

ARLP046 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 46  ARLP046
From Tad Cook, K7VVV
Seattle, WA  November 17, 2000
To all radio amateurs 

ARLP046 Propagation de K7VVV

Sunspot numbers and solar flux were down over the past week. Average
sunspot numbers were down over 40 points and average solar flux was
off by 36 points relative to the previous week. The expected
geomagnetic disturbance arrived earlier than predicted, with Friday
being the worst day, with a planetary A index of 41. Planetary K
indices reached 6 for several periods on Friday. Saturday was fairly
quiet, and Sunday was fairly active with the planetary K index at
20. Following the weekend the geomagnetic conditions have been

Solar flux probably reached a short term minimum of 143.7 on Monday,
and is now rising. Flux values for Friday through Tuesday are
expected to be 155, 155, 160, 160 and 165. Solar flux is expected to
peak around 200 from November 27-29. Expected planetary A index
values for Friday through Tuesday are 12, 10, 20, 12 and 10, so the
current predicted value for this Sunday is nearly identical to last
Sunday. The unsettled conditions on Sunday will probably be due to a
solar flair that occurred early Thursday.

Beyond the weekend, the next predicted unsettled day is November 29,
and December 5 looks like an active geomagnetic day, as well as
December 8 and 9. Of course this is based upon the previous solar

Look at the chart at It looks
as if solar flux and sunspots generally declined over the past six

Sunspot numbers for November 9 through 15 were 149, 141, 128, 112,
99, 131 and 144 with a mean of 129.1. 10.7 cm flux was 166.2, 153.4,
149.6, 146.6, 143.7, 148.6 and 146.5, with a mean of 150.7, and
estimated planetary A indices were 11, 41, 12, 21, 8, 5 and 5 with a
mean of 14.7.


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