Well, I wouldn't question that you were getting that from your note Chris - I had a hard time following your description, and suspect others may have as well. Perhaps it would be helpful to have a second description - arguably more or less vague. A disclaimer is that this is not my area of expertise - mileage may vary.
Start with a squall line, present in an atmosphere with vertical wind shear that is oriented 90 degrees to the squall line. For example, a north-south oriented line of storms, and winds at the surface being easterly to westerly in the middle atmosphere. This arrangement promotes the vertical wind shear to be tilted into the vertical by the gust front on the leading edge of the squall line - and this then promotes the development of a circulation pair - the nothern rotating counter-clockwise, southern clockwise, such that the area between the two circulations has an enhanced westerly flow. This enhanced westerly flow results in more midlevel dry air penetrating into the back side of the squall line - and that leads to more evaporational cooling - leading to locally colder air - which then sinks toward the surface. In time, this leads to a large cold pool at the surface - deepest where the most agressive cooling is taking place - and where cold air is deeper, the surface pressure is higher. This local high pressure then acts to try and spread the cold air out - most agressively from the center of the cold pool - and this surges the cold pool out near the center of the squall line fastest. Also, the enhanced westerly flow from the circulations results in faster storm motions in the center of the line than on the ends - and this aids in the line bowing out in the center, and the development of a growing area of general rain behind the leading line of storms. It is then that more focused rear inflow jets can start to develop - often in focused channels (which can appear as weaker reflectivity regions penetrating into the back of the stratiform rain region), where dry air is able to make more agressive penetrations into the stratiform rain. The lower echos associated with these comes from the local evaporation of the rain - which leds to cooling, and sinking which leads to subsidence warming and more evaporation potential, but more applicable here is this mid-level warming results in lower surface pressure beneath it - a wake low. As this sinking air builds up speed - and gets closer to the ground, it splats into the top of the surface cold pool - and locally thins it out, and since it has warmed from sinking, and warm air is lighter than cold air, leads to the development of a low pressure atop the cold pool - and that aids in acceleration of even more dry air into the back of the system - enhancing the process. Sometimes the sinking air from the rear inflow jet is able to reach down to the surface - and can result in substantial wind damage - but more often it fails to penetrate through the cold pool.
Glen
