http://www.wpc.ncep.noaa.gov/qpf/p168i.gif?1463247807
As the radar antenna turns, it emits extremely short bursts of radio waves, called pulses. Each pulse lasts about 0.00000157 seconds (1.57x10-6), with a 0.00099843-second (998.43x10-6) "listening period" in between. The transmitted radio waves move through the atmosphere at about the speed of light.
As an overview of the why's that is plaguing Texas drought conditions we must look at many factors that when mixed together are creating the present conditions and WHAT can and should be done to correct the unbalance so rain can occur naturally again across the region.