ZCZC AP23
QST de W1AW
Propagation Forecast Bulletin 23 ARLP023
From Tad Cook, K7VVV
Seattle, WA June 4, 1999
To all radio amateurs
SB PROP ARL ARLP023
ARLP023 Propagation de K7VVV
Sunspot counts and solar flux rose this past week, with the average daily sunspot number up nearly 46 points and flux values up nearly 19 points, compared to the previous week. The big day was Wednesday, when the sunspot number was 214, a big jump.
Contesters were elated when the poor conditions predicted for last weekend's WPX contest did not materialize. A coronal mass ejection sent charged particles our way, but they missed the earth, and conditions were excellent last weekend. Instead of a high A index, the planetary A index for Saturday and Sunday was only six and five, and the mid-latitude numbers, which affect most of the readers of this bulletin, were even better at three and three. In the mid-latitudes, there were many periods when the K index was zero, which is very stable.
Expect more good conditions this weekend, with the Friday through Monday solar flux predicted at 175, 170 and 170, and the planetary A index at 8, 7 and 7.
Beyond the weekend look for solar flux to drift down to 150 by June 10, bottom out around 140 from June 18-20, then rise to 165 toward the end of June. Unsettled geomagnetic conditions could return on June 9, with active conditions June 14, and unsettled to active conditions around June 21.
Earlier in the week there were several wire service stories about the predicted peak of solar cycle 23 next year, and how solar flares could disrupt various communication systems and even the power grid. One article quoted Richard Altrock of the Air Force Research Laboratory in Sunspot, New Mexico, saying that this cycle should peak between January and April of next year. He also said that the number of sunspots at the peak should roughly equal the activity during the peaks of the two previous cycles.
Sunspot Numbers for May 27 through June 2 were 154, 146, 151, 169, 157, 190 and 214 with a mean of 168.7. 10.7 cm flux was 155.2, 152.1, 148.6, 156.8, 165.4, 176 and 173.1, with a mean of 161, and estimated planetary A indices were 10, 9, 6, 5, 4, 8 and 11, with a mean of 7.6.
Here is the path projection for this weekend, which is from Chicago, Illinois. Next week the paths will originate from Dallas, Texas, and should follow the same pattern recently established. The only exceptions will be the bulletins prior to ARRL Field Day and ARRL Sweepstakes, when the paths will all be domestic only.