QST de W1AW
Propagation Forecast Bulletin 42 ARLP042
From Tad Cook, K7VVV
Seattle, WA October 20, 2000
To all radio amateurs
SB PROP ARL ARLP042
ARLP042 Propagation de K7VVV
The rise in solar flux for that was predicted this week in last week's Propagation Forecast Bulletin ARLP041 did not happen. Last week's bulletin stated that by October 18 and 19 we should see a short term peak in solar flux around 220. Instead, solar flux rose slightly over the weekend, then dropped below 160, and on October 18 and 19 it was 151.1 and 157.8. These short range predictions are based upon the previous solar rotation, plus what sunspot regions can be seen rotating toward the center of the solar disk, as well as a bet placed upon whether the activity in each region is increasing or decreasing.
The current outlook is for a slowly and modestly rising solar flux, with the values for Friday through Monday at 160, 160, 165 and 170. The latest best guess is for solar flux to peak for the short term at only 190 on October 29 and 30, then decline to 145 around November 5.
Geomagnetic conditions are expected to remain fairly stable on Friday and Saturday, but planetary A index my rise to 20 and 25 on Sunday and Monday. Geomagnetic indices are expected to calm down after that, but become unsettled to active around October 30 through November 1.
It has been some time since Propagation Forecast Bulletin ARLP032 on August 11 when we last presented a path projection. This weekend we have two. One is for the VK/ZL Oceania CW Contest, and the other is for the RSGB 21/28 MHz CW Contest. The points of origin for each path will be pretty general, one for the center of the continental U.S.A, one for the East Coast, the other for the West Coast. The solar flux value used will be 160, which represents an average of values over ten days, including the projected values for October 20 and 21. The date used for the prediction is October 21.
Sunspot numbers for October 12 through 18 were 187, 167, 157, 99, 109, 130 and 128 with a mean of 139.6. 10.7 cm flux was 162.7, 168.1, 163.3, 161.1, 160.9, 154.1 and 151.1, with a mean of 160.2, and estimated planetary A indices were 8, 27, 42, 8, 8, 9 and 8 with a mean of 15.7.