rjr@mgweed.UUCP (Bob Roehrig) (04/17/84)
qst de k9eui hr propagation forecast bulletin nr 16 from arrl headquarters newington ct april 16, 1984 to all radio amateurs bt the solar flux was down to 94 on april 9, its lowest level since early january. the curve turned downward on the 11th, and the flux was back to 119 on the 15th. the curve was leveling off at that point and another gradual decline is expected by the middle of the forecast week. the earths magnetic field was less active, so propagation actually improved overall despite the flux decline. propagation is expected to be fair to good through the 16th. thereafter, there will be frequent periods of high geomagnetic activity, with possible auroral effeqts in the northern states and canada. high latitude paths will be poor, especially on 21 and 28 mhz, but low latitude circuits will be only mildly affected. transequatorial dx activity on 50 mhz will taper off from its high level of april but it will not disappear entirely this month. sporadic e layer ionization is increasing but the major season for this mode is still several weeks away. its principal effeqt is short skip, occasionally with very high signal levels, on 28 and 50 mhz. later in the spring the number and extent of openings will increase, and e skip on 144 mhz will become more likely. american sunspot numbers for april 5 through 11 were between 1 and 60 with a mean of 28.9 ar
rjr@mgweed.UUCP (Bob Roehrig) (04/24/85)
qst de k9eui hr propagation forecast bulletin nr 16 from arrl headquarters newington ct april 21, 1985 to all radio amateurs bt the area of the sun responsible for the march solar flux peak of 80 is back with us again. the flux had been down to its cycle 21 low of 69 on april 16, but was back up to 72 on the 20th. a sizable spot group about 3 days in from the east limb of the sun showed marked eruptive activity intermittently on saturday and continuously through sunday afternoon. the solar flux jumped five points to 77 on the 21st, as propagation went from bad to worse until it began to stabilize again late that day. with the wwv k index peaking at an almost unheard of 8, reception of their propagation bulletins was all but impossible, for the first time in our 7 years of part time florida living. such near or total blackouts in the 5 to 20 mhz range are likely when the solar flux rises suddenly. more communications difficulty is likely when charged particles from the eruptions enter the earths atmosphere, some 18 to 36 hours after the event itself. this is likely to bring auroral conditions in the higher latitudes on monday or tuesday, and generally poorer propagation on all but transequatorial circuits. there may even be an enhancement on north south paths on 50 and 28 mhz at such times. if we are to have any good te work on 50 mhz this spring it should come this week. there is ordinarily a period of exceptional propagation on all dx frequencies, as a major disturbance clears up. no accurate prediction can be made for this event. the best indication is a drop in the wwv k index, given as part of their bulletin transmitted at 18 minutes past each hour. a downward trend is the thing to watch for, particularly when the k index gets down to 2 or lower. the period april 28 to may 2 is likely to bring at least one medium level disturbance. this could be followed by our first sporadic e skip of the season, on 50 mhz ar