Severe thunderstorms developed across the high plains during the afternoon on 28 May 2018, Memorial Day. In this post we focus on convection over the southern High Plains. In addition to storms developing off of the high terrain of Colorado and advancing east to the adjacent plains, convection also fired along a dryline over KS/OK/TX/NM. Using the 10.3 – 12.3 split window difference from GOES-16, forecasters could locate and track (in 5-min intervals) the precise position of the moisture gradient as early as the morning hours, prior to even the first cu development. This difference has been discussed in previous posts. With this straightforward linear grayscale color map, darker grays represent relatively drier air at the low levels, while lighter grays indicate increased low-level moisture. The key with the split window difference is to identify the gradients in the field. As an overlay on the difference is the 10.3 um IR window channel with warm brightness temperatures transparent, so only the cold cloud tops are highlighted. In this event, the aforementioned dryline is clearly evident in the difference imagery, along which convection develops. A relatively dry slot is diagnosed pushing north into southeast Colorado, west and north of which the airmass is moist again. Severe thunderstorms developed off the high terrain and into this moist region as well.
Bill Line, NWS