ZCZC AP21
QST de W1AW
Propagation Forecast Bulletin 21 ARLP021
From Tad Cook, K7VVV
Seattle, WA May 22, 1998
To all radio amateurs
SB PROP ARL ARLP021
ARLP021 Propagation de K7VVV
First thing to report this week is that geomagnetic or space weather conditions probably had nothing to do with the failure of the Galaxy 4 satellite.
Geomagnetic indices have settled over the last two weeks. Solar flux and sunspot numbers have also been generally down, but last week the average sunspot number was up about ten points while the average solar flux was off almost six points.
Until the end of the month the solar flux should rise, past 120 by May 25, and then up to 128 around May 29 and 30. Solar flux should drop down below 120 around June 2 or 3, below 110 around June 6, and below 100 after June 13. Look for unsettled conditions around May 23, and May 30 through June 2. Stable conditions are forecast around June 11 and 12.
Twenty meters is still the best HF band for DX, with daily worldwide openings. The South Pacific is strong into Seattle on that band late into the night. The ionosphere thins as the days lengthen, which means that Maximum Usable Frequency (MUF) during the daylight hours will gradually lower.
On the VHF front, W1LP in Massachusetts reported good 6 meter openings into W3, W4, W0, and New Brunswick on 2 meters into Cuba around a week ago. W1JJM reported EA7 and CT3 signals on 6 meters into Rhode Island on May 14, along with more contacts from the Northeast into the Southeast and the Caribbean on 2 meters. A 432 MHz Delaware to Florida QSO also was reported.
Sunspot numbers for May 7 through 13 were 82, 81, 56, 61, 72, 90, and 90 with a mean of 76. 10.7 cm flux was 123.3, 118, 110.7, 107.2, 108, 112.1, and 116.6, with a mean of 113.7. The estimated planetary A indices were 13, 20, 12, 11, 13, 19, and 6, with a mean of 13.4.
Sunspot numbers for May 14 through 20 were 94, 101, 92, 89, 92, 77 and 58 with a mean of 86.1. The 10.7 cm flux was 117.2, 116, 117.7, 110, 102.2, 99.7, and 91.9, with a mean of 107.8. The estimated planetary A indices were 5, 8, 12, 9, 11, 8, and 9, with a mean of 8.9.