Fine-scale structure of the prefrontal wind-shift line in the Southern Plains

This is a study of the fine-scale structure of a prefrontal wind-shift line in the Southern Plains of the U. S. on 11 Nov. 2013, using mobile Doppler radar data. Data from RaXPol (Rapid-scan, X-band, Polarimetric) located at its home base in Norman, OK, KTLX, the Twin Lakes WSR-88D radar, near Oklahoma City, and a ground-based Atmospheric Emitted Radiance Interferometer (AERI) thermodynamic profiling system, along with data from the Oklahoma Mesonet and standard rawinsonde observations are used. Evidence is presented that this prefrontal wind-shift line behaved like an “intrusion” rather than a typical density current because there was no significant temperature gradient at the surface, but there was aloft. The structure of this prefrontal wind-shift line is compared to that of the density-current-like structure of a cold front in central Oklahoma on 9 April 2013, as also determined by data collected by RaXPol. We will speculate about what is responsible for the elevated nature of the horizontal temperature gradient. It is recognized that while this case may not be representative of all prefrontal wind-shift lines, it is the first attempt, to the best knowledge of the authors, to study the fine-scale structure of a prefrontal-wind shift line using Doppler radar in clear air.