As a follow up to Jordan’s event summary for TD Beryl (http://cimmse.wordpress.com/2012/06/05/td-beryl-event-summary/), here is a radar loop from KRAX showing the interaction of TD Beryl with convective outflow from storms over western Virginia on the evening of May 29th (Fig. 1). Convection redeveloped over south-central Virginia around 09Z/30th, particularly from Kerr Lake to just north of Emporia. While the interaction may have been relatively brief within the event, rainfall rates were high enough to produce 2-3 inches in just a couple of hours (Figure 2). Such antecedent rainfall can cause major problems if it occurs ahead of the eventual track of heaviest rainfall associated with a TC. Luckily, TD Beryl moved far enough to the east and rainfall was not overly excessive, so the boundary interaction did not cause significant flooding. As Jordan mentioned in his post, this case falls within the scope of the TC QPF and Boundary Interaction project, and it a weak interaction case where the predictability of mesoscale models is especially critical to the forecast.
Figure 1 (click for loop)
Figure 2 – Radar estimated rainfall through 12z/30th.