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From: rjr@mgweed.UUCP (Bob Roehrig)
Newsgroups: net.ham-radio
Subject: arrl propagation forecast bulletin nr 39
Message-ID: <20729@mgweed.UUCP>
Date: Tue, 1-Oct-85 19:21:56 EDT
Article-I.D.: mgweed.20729
Posted: Tue Oct  1 19:21:56 1985
Date-Received: Thu, 3-Oct-85 04:47:10 EDT
Organization: AT&T Information Systems - Montgomery Illinois
Lines: 37


qst de k9eui
hr propagation forecast bulletin nr 39  from arrl headquarters
newington ct  september 30, 1985
to all radio amateurs bt

with one day to go as this bulletin  was  prepared,  the  solar
flux  average  for  september  is  69.6.   this will not change
significantly when the flux reading for the 30th is added.   we
will  then  have  our first monthly average under 70 since july
1976, the start of cycle 21.   the  present  calm  spell  began
august  11,  when a nine year low of 67 was recorded.  the flux
has been no higher than 73 since, and there have only been 3 of
these.  more important, there were 26 days under 70 in the past
2 months including one 66 and six at 67.  several  short  lived
sunspots  appeared  several  times  but the most recent visible
spot activity of any consequence came in late july.

some solar emissions that  cause  fluctuations  in  the  earths
magnetic field and increased attenuation of hf signal levels in
the higher latitudes cannot be seen in the  conventional  white
light  view  of  the  sun.   thus  the  sunspot record is not a
completely reliable indicator for  hf  propagation  prediction.
the  very erratic hf conditions of late september were typical,
with about 5 periods of 1 to 2 days each of very good and  very
bad  propagation,  following  one  another in rapid succession.
there will be more  of  this  in  october,  after  some  fairly
consistent good times early in the month.

it is believed  that  the  almost  total  absence  of  sunspots
recently  is  a temporary phenomenon, probably not an indicator
of an early end of cycle 21.  the best 8 weeks of the year  are
at hand, in any case.

american sunspot numbers  for  september  19  through  25  were
between 0 and 10 with a mean of 3.4  ar