Observations of haboobs associated with mesoscale convective vortices

Haboobs (intense dust storms commonly observed in arid regions) associated with convective outflow present a significant hazard to both surface and air transportation over the southwestern United States due to the substantial reductions to visibility. Haboobs in West Texas contributed to fatal vehicular and aircraft mishaps in 2006 and 2009, respectively. Thunderstorms often produce strong outflow boundaries, but not all outflow boundaries evolve into haboobs. Furthermore, it has been observed that the passage of one strong outflow boundary may not induce a substantive visibility reduction, yet a subsequent convective outflow minutes later over the same area may evolve into a haboob. This presents challenges for operational forecasters tasked with identifying and providing public warning for hazardous blowing dust. This also suggests that, in addition to soil and climatic variability, differences in the meteorological storm-scale or near-storm environment dictate haboob generation. This study examined radar, surface, and upper air data for three intense haboob events which occurred over West Texas between 2003 and 2009. In each case the haboob-generating outflow was anchored within a mesoscale convective vortex, with the attendant haboob arcing cyclonically and extending a horizontal distance of more than 100 km from the parent mesoscale circulation.