Can We Detect the Impact of Stability on Precipitation in Cyclones?

The impact of global warming on large-scale dynamic and thermodynamic controls of precipitation is expected to increase the intensity and frequency of strong events. Controls such as (i) stability, (ii) moisture flux convergence (MFC), and (iii) vertical motion are crucial to generating precipitation events. This presentation will explore the relationship between precipitation events associated with storms across the cyclone spectrum, including extratropical cyclones, tropical cyclones, and extratropical transitioning cyclones, and these large-scale controls, with an emphasis on stability, a less understood factor in precipitation events.

Using high spatial and temporal resolution data from the Tropical Rainfall Measurement Mission 3B42 product, we compare the cyclone lifecycle accumulated precipitation and 48-hour precipitation totals. Extratropical cyclones generate the largest amount of 48-hour precipitation totals among all storm types. Extratropical transitioning cyclones, however, generate the heaviest lifecycle accumulated precipitation. The sensitivity of these results is analyzed against the three large-scale controls listed above through analyzing the spatial and vertical distribution of stability, MFC, and vertical motion in storms as they evolve. Then, to explore the relative influence of the large-scale controls on precipitation in the cyclones, we apply conditional sorting to the precipitation by these large-scale controls. Among different height layers tested in this analysis, sorting by the 700-925 hPa layer stability was found to have the strongest correlation to precipitation. Finally, we present a new approach to quantify how sensitive different storm types are to these changing variables in the current climate.