Another View of the Development of MCS
Fig
cold pool advances forward into the warmer air; the updrafts forming along and over it and tilt rearward
As the updrafts tilt, rains falling from the storms fall further to the rear of the updrafts
At some point, the cold pool becomes deep and cold enough to rush outward toward the warm air feeding into the thunderstorm; the leading edge of the rushing air is the gust front;  a rear inflow jet (long blue) forms and flows toward the gust front.
Fig