NU-WRF Simulations of Heavy Rain Events Over Mid-West US in the Spring 2011

The spring of 2011 continent US (CONUS) was an excellent case study for climate extremes. During the April-May of 2011, there were many episodes of heavy precipitation events occurred in Midwest and Ohio Valley, which contributed to the worst flood in recorded history in the lower Mississippi River. Excessive rainfall was also found over northern States especially the Northwest. At the same time, record dry condition prevailed in the southern US. Texas and New Mexico were stricken by the worst drought in recorded history. La Nino - like large-scale circulation systems persisted from the previous winter to the spring was likely the main factor for the extreme wet conditions in the north and the hot and dry conditions in the south. The study employs NU-WRF to investigate the interactions between the large-scale forcing and local processes, especially the land surface processes to the evolution of soil moisture and atmospheric boundary conditions in the pre-season Midwest US and how these conditions affect the heavy rain events in the April-May 2011. Moisture and energy budget in the sensitivity tests will be analyzed to examine the influence of large-scale forcing and land-surface processes on the timing, intensity, and spatial distribution of the precipitation events during the period.