SB PROP @ ARRL $ARLP028
ARLP027 Propagation DE KT7H
QST DE W1AW
Propagation Forecast Bulletin 28  ARLP028
>From Tad Cook, KT7H
Seattle, WA  July 15, 1994
To All Radio Amateurs
 
The sunspot count was up a bit last week, but the solar flux was
about the same as the week before.  The sunspot number is based on
the total area and number of spots visible on the solar surface from
earth.  More sunspots of larger areas generally produce more of the
sort of radiation that makes the ionosphere reflective.
 
Solar flux is energy from the Sun measured here on Earth at 10.7 cm
wavelength, or 2.8 GHz.  It correlates fairly closely to the charged
particles reaching the ionosphere that reflect radio waves.
 
Geomagnetic disturbances were down last week, with a falling A index
in the single digits.  But on Thursday, the day this bulletin was
written, the K indices began to rise to four.  More active levels
are forecast for the next couple of days due to a recurring coronal
hole, an area on the Sun that generates disturbances here on Earth.
Another period of upset is forecast for July 23 to 28.
 
Solar flux is expected to stay in the eighties through the rest of
the month.  Broad peaks around 90 may appear centered around July 19
and August 6.
 
Sunspot Numbers from July 7 through 13 were 90, 82, 72, 92, 102, 84
and 81, with a mean of 86.1.  10.7 cm flux was 88.1, 85.8, 85.9, 86,
85.6, 82.9 and 81.4, with a mean of 85.1.
 
The path projection for this weekend is from Cleveland, Ohio to
Congo.
 
80 meters should open from 0030z to 0515z, peaking around 0200z.
40 meters should be good from 2330z to 0530z, and 30 meters from
2230z to 0600z.  Check 20 meters from 2100z to 0230z, and on some
days 17 meters may be open from 0000z to 0200z.  15 meters and above
do not look good at this time, but on rare occasions 15 meters may
open up after sundown on the Cleveland end of the path.
/EX