Tornado Alley (PROG)

[F6]

fuagf -- the basic points are that:

(1) dry air is denser/heavier than humid air at the same or even to an extent lower temperature (where cooler air is, of course, denser than warm air with the same absolute humidity), so that when the two collide, when there's low-level convergence with surface air flowing with at least some vector toward/into the dryline from either side, it's the humid air that's going to be forced to go up, the dryline and the very stable dry air behind it can be and (typically at night) often enough are pushed back to the west when there is stronger surface inflow from the humid side, but that very stable dry air is not going to rise; and

(2) drylines tend to be relatively vertical walls up to a decent distance above ground level (whereas cold fronts are [much] more sloped up back behind the surface front, as the cold air tends to undercut/seep under the warmer air ahead of the front and only become progressively deeper with distance behind the front, think blue norther [ http://investorshub.advfn.com/boards/read_msg.aspx?message_id=127274846 ]), so it's a very efficient lifting mechanism to force the initiation of storms when/to the degree there is low-level convergence at the dryline

looks like we're getting off scot-free, as the clusters to our north (having been taking up the unstable surface air from our immediate vicinity) and (in particular) to our south (having been taking up the unstable surface air that would have been flowing into our immediate vicinity to fuel storms right here) appear to have been doing a pretty good job of using up the low-level moist inflow, leaving a relative soft spot in the instability as it's traversing our immediate vicinity -- a pattern often seen (with the clusters variously located) on days like this one -- sometimes you get hit, other times just catch the edge, other times nada, complete miss even as some other vicinities not far away got hit