ZCZC AP50
QST de W1AW
Propagation Forecast Bulletin 50 ARLP050
From Tad Cook, K7VVV
Seattle, WA November 30, 2001
To all radio amateurs
SB PROP ARL ARLP050
ARLP050 Propagation de K7VVV
Average daily sunspot numbers were down by nearly 38 points this week over last, but average daily solar flux was about the same. Flux and sunspot values reached a minimum on Sunday, and are now increasing. Projected solar flux for Friday through Monday is 210, 215, 220 and 220.
A large sunspot (9715) with a complex magnetic field is moving to the center of the visible solar disk, with a straight shot at earth. This may cause some disruptions this weekend, although probably nothing like the severe geomagnetic storm that disrupted HF propagation last weekend. The predicted planetary A index for Friday through Monday is 5, 15, 30 and 15. 30 is quite disturbed, so Sunday may have high absorption of HF signals.
Last weekend the earth was blasted by energy from two coronal mass ejections. The mid-latitude A index on Saturday was 76, and the planetary A index was 108, indicating a severe geomagnetic storm. This caused dramatic aurora displays visible as far south as Arkansas and Texas in the United States. Take a look at http://spaceweather.com/aurora/gallery_24nov01.html for a dramatic gallery of aurora images.
Sunspot numbers for November 22 through 28 were 143, 144, 124, 102, 122, 139 and 180 with a mean of 136.3. 10.7 cm flux was 282.5, 177.3, 173, 170, 174.8, 190.4 and 198.5, with a mean of 195.2, and estimated planetary A indices were 8, 12, 108, 8, 5, 2 and 3 with a mean of 20.9.