20 Sep (CLIM) Raymond, Compound Storm Threats
Sep 20, 2023, 1:30 - 2:30 PM
Colin Raymond, U California Los Angeles
Compound threats from humid heat and storm systems: Assessment and process understanding
Wed, 20 Sep, 1:30, via Zoom (https://gmu.zoom.us/j/5841495324)
AOES host: Luis Ortiz
Extreme humid heat and storms are deadly hazards whose severity is expected to increase. When occurring in succession, their interaction can enhance the ultimate impacts, such as power outages removing artificial cooling during subsequent heat events. Recent projects have uncovered a substantial physical-process linkage between these two hazard types. For atmospheric rivers [ARs], we find that moist conditions amplify summertime humid heat, preferentially in the northern third of the US. By contrast, other US regions tend to experience ARs and humid heat separately, representing an important negative correlation of joint risk. For tropical cyclones [TCs], along preferred subtropical coastlines, top-1% humid heat is 3-5x more likely than normal within 24 hours of a TC passage. We employ composites, parcel tracking, and TC dynamical theory to understand the spatiotemporal patterns of this compound threat and the processes driving it. We find, for example, that record-breaking humid heat tends to occur over a much larger area for mid-latitude TCs than for tropical ones, and in areas of ascent but an absence of precipitation.