ARLP038 Propagation de K7VVV:
September 18, 1998

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 basis.

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.