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ARRL Propagation Bulletin ARLP038 (1998)

ARLP038 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 38  ARLP038
From Tad Cook, K7VVV
Seattle, WA  September 18, 1998
To all radio amateurs 

ARLP038 Propagation de K7VVV

Solar activity was down last week, with the solar flux dipping below
120, where it has not been since August 4.  The average solar flux
for the previous 90 days rose from 125 to 126, and the daily flux
was above this level on four out of seven days.  There were no major
flares or geomagnetic disturbances, and the most unsettled day was
September 12 when the planetary A index was 12.

Solar activity is rising again, and the solar flux forecast for this
Friday through Sunday is 130, 130 and 135, and the predicted
planetary A index is 10, 10 and 12.  Beyond this weekend the solar
flux is expected to rise above 140 around September 23, and peak
around 150 from September 25 through 29.  Geomagnetic conditions
should be disturbed around September 21 through 25, with the worst
conditions centered around September 23.  This is due to a recurring
coronal hole and a resulting high speed solar wind, and it may be a
good time to check VHF bands for auroral propagation.

Looking further into the future, a recent NOAA Space Environment
Center prediction shows the smoothed solar flux running about 40
points higher a year from now, and solar activity peaking around
spring, 2000.  This places the peak only about 17 to 22 months away.
Currently 15 meters is considerably better than it was a year ago,
with good daytime propagation.  20 meters is the best band all
around, with good propagation into the night.  10 meters should be
improving considerably this fall, and finally opening on a regular

On VHF, W5UWB in Texas worked LU2DEK in Argentina on six meter SSB
over a transequatorial path on September 16 at 2154z.

Good news regarding the SOHO observatory.  At one time it didn't
seem possible, but SOHO is currently pointing at the sun again and
obeying commands from ground controllers.  Now that it will have a
chance to charge batteries and warm propulsion systems, the next
step is an attempted recovery.  Check SOHO progress on the web at

Sunspot Numbers for September 10 through 16 were 123, 134, 118, 111,
106, 71 and 86 with a mean of 107.  10.7 cm flux was 141.7, 138.6,
134.9, 130.7, 121.8, 117.3 and 118.7, with a mean of 129.1, and
estimated planetary A indices were 5, 5, 12, 6, 6, 7, and 4, with a
mean of 6.4.


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