8.1 2013 realtime WRF-DART analysis and ensemble forecasts

Romine, Glen, Morris Weisman, Kate Smith, Ryan Torn, Craig Schwartz, Kevin Manning, Wei Wang, and Chris Snyder, National Center for Atmospheric Research

Realtime explicit convective forecasts at 3 km grid resolution were run from 01 May through 20 June to test the latest improvements in forecast capability with the WRF-ARW modeling system and to support the Mesoscale Predictability Experiment (MPEX). MPEX seeks to improve short-term (here 6-15 h) forecasts of convective weather events over the Great Plains. This will be achieved by increasing observation density in the vicinity of small-scale disturbances upstream of anticipated convective weather events where initial conditions are anticipated to be less certain and the assimilation of additional data could impact the subsequent forecast of convection. In addition, supplemental radiosondes will be released in the vicinity of the target region during the time convection is expected to develop. Realtime forecasts will be initialized from a continuously cycled WRF-DART ensemble data assimilation system, similar to past seasons except in 2013 a 10- or 30-member 48 h convection permitting ensemble forecast will be made twice daily. Ensemble sensitivity analysis (ESA) will offer guidance for realtime operations by identifying potential target regions for dropsondes and supplemental radiosondes. Early results highlighting analysis system performance and forecast successes and challenges will be presented at the workshop.