ZCZC AP28
QST de W1AW
Propagation Forecast Bulletin 28 ARLP028
From Tad Cook, K7VVV
Seattle, WA July 9, 1999
To all radio amateurs
SB PROP ARL ARLP028
ARLP028 Propagation de K7VVV
Average solar flux and sunspot numbers were down this week compared to last, but this is not surprising considering last week's high numbers. Average sunspot number dropped from 272 to 204, and average solar flux was down nearly 18 points to 180.8. Active geomagnetic days were Friday and Saturday when the planetary A index was 26 and 13.
The forecast for the next three days, Friday through Sunday, is a solar flux of 140, 140 and 135 and planetary A index of seven for all three days. Beyond this weekend look for a declining solar flux to continue around 135 until July 14, then go above 170 after July 19. One forecast earlier this week from the NOAA Space Environment Service Center has solar flux peaking around 200 from July 22 through 27, but a later more conservative projection suggests a peak above 180 from July 24-26.
Under current summer conditions, the 160 and 80 meter bands are noisy because of seasonal atmospherics in the northern hemisphere, while 20 meters is open late into the evening. Conditions on 10 and 12 meters will tend to get better for long distance communications as the days get shorter and we progress toward the fall equinox.
In VHF news, a number of west coast stations have been reporting signals from Hawaii via tropospheric ducting. Check the KH6FOO web page at http://hiloweb.com/kh6foo/duct.html for reports on this propagation mode, and click on the Post Ducting Report button to see the latest information.
N0LL in Kansas sent an impressive list of stations worked via 2 meter E-skip during a one hour Field Day opening, all in southeast states. He also worked an impressive number of stations around the east coast and southeast states via E-skip on July 5-7, as well as a 6 meter contact with KL7FZ on July 3.
Sunspot numbers for July 1 through 7 were 236, 232, 213, 211, 188, 190 and 158 with a mean of 204. 10.7 cm flux was 195.4, 187.1, 196.8, 185.6, 174.2, 167.9 and 158.4, with a mean of 180.8, and estimated planetary A indices were 9, 26, 13, 4, 4, 9 and 5, with a mean of 10.
The path projections for this week are from an area in Alaska between Fairbanks and Anchorage.