A Case Study of the April 29-30th Rainfall Event Along the Gulf Coast

Multiple flash flood events occurred in Alabama and the Florida Panhandle in the spring of 2014, the most significant being the April 28-30th flash flooding event in Mobile, AL and Pensacola, FL. This event had considerable societal and environmental impacts. Rain gauges in and around Mobile, recorded over 10 inches of rainfall, with gauges in Pensacola recording closer to 20 inches. The event produced rainfall that was comparable to landfalling tropical cyclones, and prompted a reaction in the local watersheds that reached historic levels. Forecasting for the historic rainfall had several challenges, notably KMOB losing radar just prior to the event which restricted the flood watches and warnings to minimal lead-time. The goals of this case study are to: 1) Identify the synoptic environment that allowed the line echo wave pattern (LEWP) mesoscale convective system (MCS) to form and thus better understand the large scale patterns that can lead to potential flash flooding events; 2) Better correlate rainfall amount to watershed discharge, allowing for radar estimations to be used to estimate potential severity of flooding; and 3) Better characterize the individualized response of several local watersheds in order to better pinpoint favorable locations for flooding/severe flooding.