You certainly heard about the Dallas tornado Sunday night and, if not, you can get the full story from Click2houston.com right here.
I want to explore the wind set up for this event because another front is headed into Texas on Thursday and a similar severe weather outbreak is possible.
One of the most important factors is the jet stream position. These are winds up around where airline passenger jets fly (33,000 feet) and are very fast (easily 100-125 mph). Consequently, they move wind quickly from UP TOP and air below will rush upward to fill the gap. Kind of like if you move your arm across the water at the top of a swimming pool, the water below rises quickly to replace it. Take a look at Sunday's Jet Stream:
Right across North Texas! In addition, when those winds rush upward (known as vertical velocity) the horizontal winds coming in from different directions (in this case, SE, SW, W and NW) also increase and when you have different wind directions at different heights above the earth, that is when you get a spinning column of air: A tornado.
You can see these different wind directions last night from the 850 mb map (about 5000 feet above the earth):