QST de W1AW
Propagation Forecast Bulletin 31 ARLP031
From Tad Cook, K7VVV
Seattle, WA July 26, 2002
To all radio amateurs
SB PROP ARL ARLP031
ARLP031 Propagation de K7VVV
Active sunspot regions have been coming into view, with a resulting rise in solar flux and sunspot numbers. Average daily sunspot numbers were up nearly 30 points, and solar flux up about the same amount when compared to the previous week. Wednesday had a very high sunspot number of 270, the highest since May 4th and 5th, when it reached 271 and 317.
On July 23 sunspot 39 emitted a strong flare, but didn't cause any major upset. Planetary K indices on Thursday are running between two and three. But earlier in the week the geomagnetic field was quite unsettled, with planetary K indices of four from July 20-23. On July 22 the planetary K index reached five, and Alaska's high latitude college K index went to six.
Sunspot numbers are expected to remain fairly high, continuing above 200 over the next few days. As long as there aren't any geomagnetic storms, this is good for HF propagation. The current outlook for Friday through Monday is solar flux at 220, 220, 225 and 225, and a mild geomagnetic outlook with predicted planetary A index values of 15, 10, 10 and 8.
Last week's bulletin mentioned a source for historical sunspot data at ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/. NG3K wrote to say that when he saw the bulletin, the link was missing the underline characters between SOLAR and DATA and between SUNSPOT and NUMBERS. Without these, the link was bad. Apparently the bulletin was sent over some mediums this way. With luck it won't happen with the same link as it is repeated above. NG3K has a nice web site devoted to DX and contesting at www.ng3k.com.
Sunspot numbers for July 18 through 24 were 166, 148, 136, 131, 176, 226 and 270, with a mean of 179. 10.7 cm flux was 180.7, 182.3, 184.8, 182.8, 189.7, 198.3, and 208.4, with a mean of 189.6. Estimated planetary A indices were 8, 12, 18, 19, 20, 18, and 12, with a mean of 15.3.