April 2011 was an unusually prolific month for tornadoes in the eastern half of the United States, with more than 450 tornadoes east of the Mississippi River officially recorded to date in the Storm Data publication. The National Weather Service (NWS) Baltimore/Washington Forecast Office in Sterling, VA (WFO LWX) experienced two significant tornadic episodes during this time, which have contributed to a record tornado season in the WFO LWX forecast area. During the 27-28 April tornado outbreak, portions of the WFO LWX forecast area were under a Tornado Watch for nearly 24 hours (an unprecedented length of time for this part of the country), with at least 19 tornadoes of EF-0 to EF-2 intensity during a 17-hour period.

The WFO LWX forecast area is unique owing to the presence of four Federal Aviation Administration Terminal Doppler Weather Radars (TDWRs) in addition to the NWS Weather Surveillance Radar-88 Doppler (WSR-88D). The four TDWRs offer warning forecasters one-minute updates of low-level reflectivity and velocity data in addition to the four-minute volume scan updates provided by the WSR-88D. Owing to the comparatively higher temporal and spatial resolution of the TDWR data, low-level reflectivity and velocity features are detected and tracked far more readily than in WSR-88D data.

After a cursory presentation of the synoptic evolutions of the 16 April and historic 27-28 April events, a dual-radar examination of a close-proximity mesocyclonic tornado embedded in a convective line will be presented in addition to depictions of cyclic non-mesocyclonic tornadogenesis processes in a quasi-linear convective system. Data from some of the 27-28 April tornadoes also will be examined, as will the impacts and implications of this data on operations, warning decisions and subsequent storm surveys.