Topband: Correlation between AM BCB propagation and topband?

[Richard (Rick) Karlquist]

I am writing this at 03150 UTC on Jan 5.  About
3/4 hour ago, I was listening to KOH radio on 780
kHz from the San Francisco area, something like
150 miles away.  At that time WBBM radio (also on
780 kHz) in Chicago, ~2000 miles away was so strong that it
completely took over the channel from KOH.
And I was just listening on a car radio with a
2 foot whip antenna.  During the last month or so
of good 160 meter propagation, WBBM has been
heard underneath KOH, which is very usual as it is.
But to overpower KOH is unprecedented.
I have listened to KOH for years, and never noticed
WBBM until the last few months, although I was
aware it was there since I used to live in
Chicago.  In a similar incident a number of years
ago, WJR in Detroit on 760 kHz overpowered KFMB
in San Diego, which is normally very strong near
San Francisco.

I am just wondering if any great propagation is
currently taking place on 160 meters, if the
bands are somehow correlated.  Maybe this could
be some kind of propagation indicator.  Unfortunately,
my internet connection to the remote base is
down right now.

Rick N6RK