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The K7VVV Solar Update

SEATTLE, WA, Dec 8, 2000--Average solar flux was down and sunspot numbers were up this week. At least there weren't any major geomagnetic disturbances. Quiet and stable conditions prevailed, with A indices in the single digits. Solar flux probably reached a short term minimum at 1800 UTC on December 6 of 140.2, and at the 1800 UTC reading the next day it was 140.8. The official daily readings are at 2000 UTC, which is why you won't see those numbers reported here in the summary at the end of this bulletin.

After the low flux numbers for the previous two days, solar flux is expected to rise to a peak near 200 around December 20-23. Current prediction shows flux values for Friday through Tuesday, December 8-12 at 145, 150, 150, 155 and 160. The next short term minimum for solar flux is predicted for after the new year.

Unfortunately for hams looking forward to the ARRL 10-Meter contest this weekend, the quiet conditions probably will not continue. Predicted planetary A index for Friday through Tuesday is 15, 25, 15, 12 and 10. The active conditions in this weekend's forecast are probably due to a coronal hole in the center of the visible solar disk. This will be a problem for high latitude and east-west propagation. There was also a solar flare toward the end of the UTC day on December 6.

Sunspot numbers for November 30 through December 6 were 191, 157, 141, 186, 120, 90 and 99 with a mean of 140.6. The 10.7 cm flux was 192.3, 184.5, 167, 163.6, 152, 147 and 141, with a mean of 163.9. The estimated planetary A indices were 6, 6, 4, 12, 10, 4 and 7 with a mean of 7.

Amateur solar observer Tad Cook, K7VVV Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version also appears in The ARRL Letter. Readers may contact the author via k7vvv@arrl.net.

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