Bart Geerts, Thomas Andretta, Stephanie Luberda, Jennifer Vogt, Yonggang Wang, Larry Oolman, Jonathan Finch, Dan Bikos<\/em><\/p>\n On 22 May 2008 a long-lived mesocyclone spawned an EF2 tornado over terrain as high as 2650 m MSL in southeastern Wyoming. \u00a0The mesocyclone was part of an elongated, complex storm system that grew rather early in the day near a slow-moving warm front. \u00a0The mesocyclone is unusual in that it persisted and became tornadic in rather cold (~7\u00b0C), saturated surface conditions in an environment with CAPE < 1000 J kg-1<\/sup>\u00a0and no surface-based convective inhibition. \u00a0The mesocyclone intensified as its parent storm moved over terrain gradually ascending by ~1000 m, reaching a radar-estimated low-level horizontal shear as high as 84 m s-1<\/sup>\u00a0km-1<\/sup>. \u00a0This fast-moving mesocyclone could be tracked by the nearest Doppler radar for over 90 min.<\/p>\n This paper examines the characteristics and the environment of this mesocyclone using both operational weather data and high-resolution numerical simulations. Near-surface radar observations and model output suggest that the formation and maintenance of the mesocyclone in this low-CAPE environment benefited from two terrain-related factors. One is the observed channeling of the low-level flow, locally enhancing the storm-relative helicity. \u00a0The second is the presence, suggested by high-resolution simulations, of banners of high potential vorticity generated by the strong southerly flow shearing around the Colorado Front Range.<\/p>\nAbstract<\/h4>\n