Outstanding Publication Award

Roy Rasmussen, Ben Bernstein, and Greg Stossmeister. Co-nominees and co-authors included Masataka Murakami (Meteorological Research Institute, Tsukuba, Japan), Jon Reisner (Los Alamos National Laboratory) and Boba Stankov (NOAA).
Award Year
Award Type
Awarding Organization or Entity

Shallow upslope storms, which develop along the Front Range two to six times per year and last from three to four days each, are of great interest to atmospheric scientists as well as to pilots. The storms' relatively warm cloud tops allow droplets to remain unfrozen for long periods, posing a significant aviation hazard. This study examines a 1990 storm in detail, showing the dynamical and microphysical mechanisms that led to long-lived regions of supercooled liquid water and freezing drizzle aloft. These mechanisms include upper-level jet streaks, which can help suppress vertical development of the precipitation, and sequential surges of cold air, which at first hasten but eventually diminish the production of supercooled liquid water. Insights from this and later work have led to improved pilot training, better algorithms of in-flight icing, and improved paramaterization of supercooled liquid water in mesoscale models.