Warm-Season Stationary Fronts East of the Rocky Mountains: Interannual Distribution and Variability

Stationary fronts (SFs) often have an influence on convection, although this relationship is not entirely understood. A first step to more completely understand this relationship is to determine the frequency and spatial distribution of SFs across many years. An examination of North American SFs east of the Rocky Mountains during the warm months (April–September) of 2007 through 2015 provides a nine-year climatology to launch this investigation. This data was retrieved Weather Prediction Center surface analysis maps examined four-times daily at standard synoptic times.

Of the 6588 maps examined during this time period, a total of 3528 SFs were recorded. SFs were most frequent in the 2014 warm-season and least in 2008, with 451 and 301 respectively. The spatial frequency of SFs over the nine-year climatology was determined by the number of periods (single maps) that an SF was present in an area. The regions of the highest SF frequency across the nine-year climatology were found to be along the Carolina coast and in western Kansas. However, there was interannual variability in this spatial distribution with those in 2007 through 2011 most frequent in the Kansas/Oklahoma region while those in 2012 through 2015 were most frequent in the Southeast U.S./Carolina coast region. This poster will explore this interannual variability and its importance given the close link between stationary fronts and warm-season convection.