ARRL

ARRL Propagation Bulletin ARLP030 (2001)

SB PROP @ ARL $ARLP030
ARLP030 Propagation de K7VVV

ZCZC AP30
QST de W1AW  
Propagation Forecast Bulletin 30  ARLP030
From Tad Cook, K7VVV
Seattle, WA  July 20, 2001
To all radio amateurs 

SB PROP ARL ARLP030
ARLP030 Propagation de K7VVV

Last week's Propagation Forecast Bulletin ARLP029 stated that the
next peak in solar flux would probably be near 170 around July
20-22. This now appears a bit optimistic based upon current
readings. Solar flux and sunspot numbers have been up this week, but
flux values probably reached a peak on Monday when the noon reading
was 149.8.

Current forecasts show flux values slowly drifting downward over the
next week, with values around 140 from Friday through Monday, then
between 135 and 140 until around the end of the month.

Over the past week the average daily solar flux was up nearly 17
points and average sunspot numbers increased by over 63 points, when
compared with the previous week's report.

Due to a persistent solar wind, geomagnetic conditions became
unsettled to active this week. The most active days were Monday and
Tuesday, when the planetary A index was 17. Alaska's College A index
was also 17 on Monday, but jumped to 31 on Tuesday, when K indices
went as high as 5 over several periods.

A slowly erupting coronal mass ejection billowed away from the sun
on Tuesday, but there is little chance that it will affect the
earth's magnetosphere.

Sunspot numbers for July 12 through 18 were 119, 146, 161, 142, 179,
191 and 193 with a mean of 161.6. 10.7 cm flux was 133.9, 133.3,
140.8, 142.1, 149.8, 145.6 and 143, with a mean of 141.2, and
estimated planetary A indices were 9, 9, 13, 11, 17, 17 and 11 with
a mean of 12.4.
NNNN
/EX