Dynamics of rainfall distribution patterns associated with tropical cyclones affected southern Appalachians

A thorough analysis of rainfall distributions associated with tropical cyclones that have impinged upon or impacted the southern and central Appalachian mountain range is conducted, using the North America Regional Reanalysis (NARR). Based on the relative positions between the tropical cyclone tracks and the orientation of the Appalachian mountains, four storm tracks and their associated rainfall patterns are classified. Local rainfall maxima are obtained identifying areas with the highest potential for flooding for each representative track. For storm tracks running parallel on the eastern side of the Appalachians (Type I), the heavy rainfall is located along eastern slopes with the heaviest precipitation falling on western North Carolina and northern Virginia. On the other hand, for storm tracks running parallel on the western side of the Appalachians (Type II), the heavy rainfall is located on western slopes with the heaviest precipitation falling on west of central Kentucky. For storm tracks running approximately perpendicular to the mountain range (Types III and IV), the rainfall is located in northern Virginia with concentrated maximum.

These locations are analyzed and conceptualized in a dynamical sense using individual case studies. We hypothesize that the rainfall distribution is controlled by the impinging angles between the outer circulation of the storm and the orientation of the mountain range. Upon forecasting tracks of future landfalling tropical cyclones impinging upon the Appalachians, it is possible to forecast with improved skill and precision where relative maxima and minima will occur in the rainfall distribution.