Topband: Large TSTM areas as MF "wall"

[Thomas Giella, KN4LF]

Mac PY2CW Asked:  Questions: A large thunderstorm area in the dx path is a
factor for weaker sigs?
                           Charged clouds "blocks" ground wave ? What is the
mechanism ?

Thomas KN4LF Says:
  As a retired Meteorologist and Space Weather Forecaster I can say that
temperature and moisture discontinuities in the vicinity of a cold front can
refract 160 meter signals in unpredictable ways but the electrical signature
of a thunderstorm complex does not block 160 meter RF signals. Of course the
high QRN level will mask low band signals though.
  As far as propagation conditions the last two nights in Florida, UTC
Saturday was poor with only and occasional whisper from Europe, with
Canadian stations down approximately 20 db. UTC Sunday was better but still
depressed, with VC2C peaking at  59+5 and IH9P 59+10.

73,
Thomas Giella
KN4LF