Influence of Prescribed Rocky Mountain Springtime Snowpack on Evolution of Summertime Precipitation in the Great Plains

Warm season droughts are naturally occurring, high impact phenomena that frequent the Great Plains region of the United States. Their modern and historical cost to society have been considerable, often costing the US economy billions of dollars in dry years. In order to mitigate and forecast such events, determining and understanding both the global and local drivers of summertime drought evolution is paramount. Past research has linked global teleconnections such as the phase and amplitude of ENSO as well as the magnitude and location of Pacific Ocean sea surface temperature anomalies to central US drought formation and evolution. Since global scale influences can’t explain all drought variability in the Great Plains, focus must also be placed on local drought-related processes related to land-atmosphere interactions such as surface evapotranspiration and the timing and magnitude of meltwater runoff from the Rocky Mountain snowpack.

Thus, in order to gain better understanding of drought in the Great Plains, it is important to quantify the influence of remote and local factors and how each driver may influence drought singularly as well as collectively. This study focuses on the local/regional variable of prescribed springtime snowpack in the Rocky Mountains and how various spring snowpack assignments may affect summertime drought evolution in the Great Plains. The Rocky Mountain snowpack variable is chosen since it is yearly variable, it can alter the thermodynamic and radiative budgets, and spring and summer runoff from the mountains can largely determine water availability. Hence, it is possible that altering springtime snowpack regimes in the Rockies may influence summertime drought evolution in the Great Plains through altered runoff amounts and affect atmospheric circulation patterns by modifying the zonal temperature gradients over the region. In order to investigate this issue the Weather Research and Forecasting (WRF) Model is utilized to explore the impacts various prescribed springtime snowpack coverages may have on the evolution of summertime drought in the Great Plains. More specifically, changes in the low-level jet, soil moisture gradients, and precipitation sequences are investigated. It is anticipated that the WRF modeling results will help to build a better understanding of the importance of Rocky Mountain spring snowpack to drought in the Great Plains.