ARRL

ARRL Propagation Bulletin ARLP007 (2000)

SB PROP @ ARL $ARLP007
ARLP007 Propagation de K7VVV

ZCZC AP07
QST de W1AW  
Propagation Forecast Bulletin 7  ARLP007
From Tad Cook, K7VVV
Seattle, WA  February 18, 2000
To all radio amateurs 

SB PROP ARL ARLP007
ARLP007 Propagation de K7VVV

Solar flux and sunspot counts increased the week before last, fell
last week, and the averages for both weeks were about the same.
Average solar flux was down about 11 points last week, and average
sunspot numbers were off by a little over one point.  Last weekend
had a surprising burst of geomagnetic activity, when Saturday's
planetary A index was 52.  The planetary K index was as high as 7,
and Alaska's College A index, which is frequently higher because of
its proximity to the pole, was 71.  During a six hour period, from
0600-1200z, the planetary A index was 7 and 6 while the College A
index was 8 and 7.  These all indicate severe geomagnetic storm
levels.

What should we see over the next week?  For the next five days,
Friday through Tuesday, solar flux is predicted to be 155, 150, 150,
145 and 145.  Planetary A index for those same days is forecast to
be 5, 5, 12, 8 and 8.  For best HF conditions, we want a low A index
in the single digits, and rising solar flux.  So Sunday, February 20
with a planetary A index of 12 could be somewhat unsettled.

Solar flux for the short term is expected to bottom out near 130
around February 25, then rise to about 150 by March 1, but peak
broadly and fairly low near 175 around March 4-8.  The next
predicted short term minimum is forecast for March 23-24.  Of course
these are all guesses based upon activity over previous solar
rotations, which occur about every 27.5 days.  Since the predicted
high levels of 175 are much lower than previous rotations where
solar flux was above 200, this means that the prediction is based
upon sunspot regions which are currently fading.  Any new sunspot
areas will probably result in increased solar flux and better HF
conditions.  With spring coming, it would be nice to see extended
worldwide openings on 10 and 12 meters again, which would accompany
the high flux levels normally expected in a peak year of a solar
cycle.

Sunspot numbers for February 10 through 16 were 172, 184, 157, 147,
158, 158 and 182 with a mean of 165.4.  10.7 cm flux was 175.7
170.2, 163.2, 159.9, 158.7, 156 and 160.2, with a mean of 163.4, and
estimated planetary A indices were 7, 13, 52, 14, 29, 11 and 5, with
a mean of 18.7.

Path projections for this weekend are from a place in Arizona
between Tucson and Phoenix, near Eloy.

To Western Europe, 80 meters 0100-0830z, 40 meters 0000-0930z, 30
meters 2330-1030z, 20 meters 1400-1600z and 2200-0000z, 17 meters
1430-2100z, 15 meters 1500-2000z, 12 meters 1600-1830z, 10 meters
around 1700z.

To Eastern Europe, 80 meters 0030-0630z, 40 meters 0000-0800z, 30
meters 2330-0830z, 20 meters 1330-1530z, 17 meters 1430-1830z, 15
meters 1530-1800z, 12 meters 1600-1630z.

To Southern Africa, 80 meters 0030-0430z, 40 meters 0030-0500z, 30
meters and 20 meters 2330-0530z, 17 meters 2300-0100z, 15 meters
2300-0000z, 12 meters 2130-2230z, 10 meters 2000-2130z.

To South America, 80 meters 0100-1000z, 40 meters 0030-1030z, 30
meters 0000-1100z, 20 meters 2330-1200z, 17 meters 1330-1400z and
2230-0500z, 15 meters 1400-1500z and 2130-0230z, 12 meters
1430-1600z and 2030-0200z, 10 meters 1500-0100z.

To the Caribbean, 80 meters 0000-1130z, 40 meters 2330-1230z, 30
meters 2200-1400z, 20 meters 1300-0830z, 17 meters 1400-0100z, 15
meters 1430-0000z, 12 meters 1500-2300z, 10 meters 1530-2200z.

To Australia, 80 and 40 meters 0930-1500z, 30 meters 0900-1500z, 20
meters 0830-1530z, 17 meters 0700-1100z and 1500-1630z, 15 meters
around 1500z and around 0430z.

To Japan, 80 meters 0800-1500z, 40 meters 0700-1500z, 30 meters
0630-1600z, 20 meters 0530-1700z, 17 meters 2100-0430z, 15 meters
2100-0400z, 12 meters 2130-0230z, 10 meters 2200-0130z.
NNNN
/EX