Climate change and hazardous convective weather in the United States: Insights from high-resolution dynamical downscaling

Kimberly A Hoogewind, Purdue University


Global climate model (GCM) projections increasingly suggest that large-scale environmental conditions favorable for hazardous convective weather (HCW) may increase in frequency in the future due to anthropogenic climate change. However, this storm environment-based approach is undoubtedly limited by the assumption that convective-scale phenomena will be realized within these environments. The spatial resolution of GCMs remains much too coarse to adequately represent the scales at which severe convective storms occur, including processes that may lead to storm initiation. With the advancement of computing resources, however, it has now become feasible to explicitly represent deep convective storms within a high-resolution regional climate model. This research utilized the Weather Research and Forecasting (WRF) model to produce high-resolution, dynamically downscaled simulations for the continental United States under historical (1971--2000) and future (2071--2100) climate periods using GCM data provided by the Geophysical Fluid Dynamic Laboratory Climate Model version 3 (GFDL-CM3). Model proxies were used to provide an objective estimate of the occurrence of simulated severe weather and how their spatiotemporal distribution may change in the future under an aggressive climate change scenario. Results demonstrated that severe storms may increase in both their frequency and intensity in the future. In comparison to the projected changes in HCW favorable environments from the GCM, the dynamically downscaled largely agree in terms of the seasonal timing and spatial patterns of greatest potential change in activity by the end of the 21st century. Likewise, each approach supports the notion that severe weather activity may begin earlier within the annual cycle and also later within the calendar year, such that the severe weather season is lengthened. However, by all indications, the environment-event frequency relationship has been altered in future climate, such that the uptick in the number of days with simulated HCW events does not increase proportionally to the rise in days with HCW favorable environments. Such an outcome supports the motivation for continued use of dynamical downscaling to overcome the limitations of the GCM-based environmental analysis.




Trapp, Purdue University.

Subject Area

Climate Change|Atmospheric sciences

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