Preliminary Numerical Simulations of Sudden Warming from Chinooks in the Lee of the Alaska Range

Southerly foehns off the Alaska Range, where such winds are called chinooks, can raise 2-m temperatures by tens of degrees (C) in just minutes. Mesoscale numerical weather prediction models often struggle to predict accurately the timing, magnitude, and spatial distribution of these sudden warmings. The authors use preliminary idealized and realistic simulations of chinooks to begin exploring how these warmings occur, why they are difficult to predict, and what improvements can be made to numerical models and their initial- and boundary conditions to increase predictive skill. Foci of the study include the synoptic and mesoscale conditions that precede some chinooks, and the shallow, strong cold pools in the lee of the Alaska Range that set the stage for sudden warmings. The authors hypothesize that these cold pools partly explain why some chinooks in the region are so challenging for mesoscale models.