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ARRL Propagation Bulletin ARLP048 (2002)

ARLP048 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 48  ARLP048
From Tad Cook, K7VVV
Seattle, WA  November 22, 2002
To all radio amateurs 

ARLP048 Propagation de K7VVV

No geomagnetic storm emerged for last weekend's ARRL Phone
Sweepstakes. Conditions were very quiet, with the mid-latitude A
index for Friday through Sunday a placid 8, 3 and 5, and the
planetary A index at 11, 8 and 8. Mid-latitude K indices were 0 over
several periods on Saturday and Sunday, which is fabulous for HF

Average daily sunspot numbers were down over 62 points this week
over last, and average solar flux was down nearly 5 points.

Again at the end of this week earth is within a solar wind stream
causing a rise in geomagnetic indices and likely to cause aurora.
Sunspot 198, squarely aimed at earth on Thursday has a potential for
solar flares.

On Thursday (November 21) the planetary K index rose to a very high
value of 7, and the planetary A index was 50. The planetary A index
has not been this high since October 1. Also on Thursday the high
latitude College A index (measured in Alaska) was 62. For the CW
weekend of the CQ Worldwide DX Contest the predicted planetary A
index for Friday through Sunday is 35, 20 and 15. Solar flux is
predicted to rise very gradually over the next few weeks to just
below 200 before mid-December.

The winter solstice is a month away. As the hours of daylight
recede, higher bands are closing earlier, but 20 meters should still
stay open into the evening, often to points in the southern
hemisphere. Nighttime MUF's (Maximum Usable Frequency) will be
somewhat lower as the days get shorter, so 40 and 80 meters will
become more desirable. For instance, using W6ELprop to check MUF
between Seattle and Japan with a solar flux of 155, on November 21
the period with MUF below 10 MHz runs from 1330-1430z, but on
December 21 it is from 1300-1530z.

Sunspot numbers for November 14 through 20 were 185, 185, 162, 139,
119, 105, and 108, with a mean of 143.3. 10.7 cm flux was 184.1,
197.5, 199.2, 184.7, 178.9, 168.2, and 159.1, with a mean of 181.7.
Estimated planetary A indices were 9, 11, 8, 8, 12, 14, and 17, with
a mean of 11.3.


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