DF2PY:
> It seems that solely watching A and K indexes plus the
SFI is not helping much in propagation predictions, at least not for
160.
There are many other factors affecting 160, and probably many
we do not fully understand. K4CIA recently mentioned the following
article about stratospheric warming:
http://bit.ly/SWCunv
Many years ago the WWV announcements included "stratwarm" alerts
but I noticed it was missing from today's 1218z announcement. When
I was in Colorado I usually found very poor propagation on 160
followed a stratwarm alert. High absorption caused by stratwarm
has also been called the "mid-winter anomaly" which has been known
about for many years.
"Weather Events" in the Upper Atmosphere
D-region Winter Anomaly is a period of enhanced radio wave absorption
usually occurring in late winter and thought to be associated with a sudden
stratospheric warming
http://www.albany.edu/faculty/rgk/atm101/weather.htm
Hang in there...this too shall pass!
73, Bill W4ZV
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Topband Reflector
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