ARRL

ARRL Propagation Bulletin ARLP030 (1997)

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 25, 1997
To all radio amateurs

SB PROP ARL ARLP030
ARLP030 Propagation de K7VVV

This week finally saw a welcome rise in solar activity and the
accompanying improvement in HF radio conditions.  Solar flux rose
above 70 on July 19, was above 72 on July 22, and then at 1700, 2000
and 2300 UTC on July 23 it reached 75.6, 75.7 and 75.8, and at the
same times on July 24 it was 77, 78.7 and 79.  The 2000 UTC
measurement at Penticton, BC is the one reported in this bulletin.

The really great news is that with three active regions on the solar
disk, this trend is expected to continue, with flux values around
80, 82 and 82 expected for July 25, 26 and 27.  Fortunately, there
is no expected rise in geomagnetic indices to go along with the
increased activity, so HF conditions should remain stable.

R. Brendle wrote to say that he operates several commercial and GMRS
UHF repeaters in Eastern Nebraska, and that the seasonal ducting
this year is the longest and most sustained he has ever seen.
Normally this only happens during overcast and humid conditions
during a severe weather watch, but the most recent period lasted
over two weeks.

On HF, look for excellent worldwide propagation over the next few
days with higher solar flux and continued low A and K indices.

Sunspot Numbers for July 17 through 23 were 11, 11, 0, 12, 0, 11 and
31 with a mean of 10.9.  10.7 cm flux was 69.9, 70.1, 71, 71.2,
71.3, 72.2 and 75.7, with a mean of 71.6, and estimated planetary A
indices were 8, 10, 11, 6, 5, 4, and 5, with a mean of 7.
NNNN
/EX