ZCZC AP51
QST de W1AW
Propagation Forecast Bulletin 51 ARLP051
From Tad Cook, K7VVV
Seattle, WA December 3, 2001
To all radio amateurs
SB PROP ARL ARLP051
ARLP051 Propagation de K7VVV
This bulletin corrects a piece of data that was in Propagation Forecast Bulletin ARLP050, released on November 30, 2001.
Sometimes during a period of high solar activity the device which reads the solar flux at the Penticton observatory gets overwhelmed by a solar flare, and the reported value is adjusted downward. Readers who use Scott Craig's Solar Data Plotting Utility (download it free from http://www.craigcentral.com/sol.htm ) probably noticed a spike in the solar flux number from November 22, when the value jumped nearly 100 points to 282.5 from 184.2 the day before and then back to 177.3 on Friday.
That value was adjusted by NOAA, and should read 190. It is corrected in the list of numbers at the bottom of this bulletin. This means that the average solar flux for the week was 182, not 195.2.
Solar flux has been rising, and for the next few days look for flux values around 245 for Monday through Wednesday. The planetary A index may rise to around 15 on Tuesday and Wednesday, indicating unsettled conditions.
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 190, 177.3, 173, 170, 174.8, 190.4 and 198.5, with a mean of 182, and estimated planetary A indices were 8, 12, 108, 8, 5, 2 and 3 with a mean of 20.9.